%0 Journal Article
%T Large Deflection Model for Multiple, Inline, Interacting Cantilever Beams
%A Bebee, Austin
%A Stubbs, Christopher J.
%A Robertson, Daniel J.
%J Journal of Applied Mechanics
%V 88
%D 2021
%8 April 01, 2021
%P 041005
%U https://ui.adsabs.harvard.edu/abs/2021JAM....88d1005B
%R 10.1115/1.4049072


%0 Conference Proceedings
%T Initial assessment of monocrystalline silicon solar cells as large-area sensors for precise flux calibration
%A Brownsberger, Sasha
%A Mondrik, Nicholas
%A Stubbs, Christopher W.
%+ AA(Harvard Univ. (United States)), AB(Harvard Univ. (United States)), AC(Harvard Univ. (United States))
%J Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
%V 11454
%D 2020
%8 December 01, 2020
%P 114542C
%U https://ui.adsabs.harvard.edu/abs/2020SPIE11454E..2CB
%X As the precision frontier of large-area survey astrophysics advances towards the one millimagnitude level, flux calibration of astronomical instrumentation remains an ongoing challenge. We describe initial testing of silicon solar cells as large-aperture precise calibration photo- diodes. We present measurements of dark current, linearity, frequency response, spatial response uniformity, and noise characteristics of the Sunpower C60 solar cells, an interdigitated back-contact 125mm x 125mm monocrystalline solar cell. We find that these devices may hold promise as large-area flux calibration sensors, and that further analyses over a broader range of operating conditions are necessary. Flux calibration remains a primary source of systematic uncertainty in the use of type Ia supernovae (SNe Ia) as probes of the history of cosmic expansion [1, 2, 3, 4]. The wavelength-dependent throughput of the observing instrument is the most immediately accessible and separable contribution to this systematic error. One approach for flux calibration is to invoke models of photon emission spectra vs. wavelength for a simple stellar atmosphere, white dwarf stars being the most popular [5]. This calibration method includes contributions from the instrument throughput, but is also affected by uncertainties in Galactic and atmospheric extinction, and other systematic effects. A supplemental approach that isolates the instrument throughput is to use well-characterized sensors as the metrology standard for relative flux determination [6, 7, 8, 9, 10]. In this approach a well-calibrated photodetector, known to better than a part per thousand, [11] is used to map out the instrument's relative sensitivity vs. wavelength. Conventional photon- detectors (photodiodes, CCDs, etc) have collection areas no larger than a few square centimeters. Such small collection areas are inadequate for some mod- ern imaging applications that depend on the calibration of a large-diameter optical beam. The Large Synoptic Survey Telescope [12] (LSST) project intends to use a collimated, monochromatic beam (a Collimated Beam Projector, or CBP), to sequentially illuminate portions of the optics, and a calibrated silicon photodiode to monitor the flux [13, 14]. The LSST team plans to use the CBP to measure instrument transmission as a function of photon wavelength and source position. One metrology challenge of this approach is to measure the flux emanating from the CBP, which has an exit pupil diameter of 240 mm, about twenty times larger than the diameter of typical silicon photodiodes. The LSST team is considering several solutions to this unsolved problem, including changing the projector beam focus to reduce the spot size, collecting the light with a focusing concentrator, using an integrating sphere with a 250mm port, or scanning the exit beam across one or more standard calibrated photodiodes. Each of these approaches, all suboptimal, are born of a perceived need to measure a large light source with a small detector. In this paper we consider the possibility of using an array of high-efficiency solar cells as a full-aperture sensor for calibrating the LSST CBP and other large-diameter internal calibration light sources. In Section 1, we describe the general architecture of an interdigitated back-contact monocrystalline silicon solar cell and introduce the C60 solar cells that we study. In Section 2, we describe the methods and results of our measurements. We conclude in Section 3, where we summarize the results of our experiments and discuss what additional steps should be taken to fully assess the prospect of creating a precision photometric calibrator composed of solar cells.
%R 10.1117/12.2564972


%0 Journal Article
%T Understanding interfacial fracture behavior between microinterlocked soft layers using physics-based cohesive zone modeling
%A Baban, Navajit S.
%A Orozaliev, Ajymurat
%A Stubbs, Christopher J.
%A Song, Yong Ak
%+ AA(Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates; Department of Mechanical and Aerospace Engineering, New York University, New York, New York 11201, USA), AB(Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates), AC(Department of Mechanical Engineering, University of Idaho, Moscow, Idaho 83848, USA), AD(Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates; Department of Chemical and Biomolecular Engineering, New York University, New York, New York 11201, USA)
%J Physical Review E
%V 102
%D 2020
%8 July 01, 2020
%P 012801
%U https://ui.adsabs.harvard.edu/abs/2020PhRvE.102a2801B
%X We examine the underlying fracture mechanics of the human skin dermal-epidermal layer's microinterlocks using a physics-based cohesive zone finite-element model. Using microfabrication techniques, we fabricated highly dense arrays of spherical microstructures of radius ≈50 μ m without and with undercuts, which occur in an open spherical cavity whose centroid lies below the microstructure surface to create microinterlocks in polydimethylsiloxane layers. From experimental peel tests, we find that the maximum density microinterlocks without and with undercuts enable the respective ≈4 -fold and ≈5 -fold increase in adhesion strength as compared to the plain layers. Critical visualization of the single microinterlock fracture from the cohesive zone model reveals a contact interaction-based phenomena where the primary propagating crack is arrested and the secondary crack is initiated in the microinterlocked area. Strain energy energetics confirmed significantly lower strain energy dissipation for the microinterlock with the undercut as compared to its nonundercut counterpart. These phenomena are completely absent in a plain interface fracture where the fracture propagates catastrophically without any arrests. These events confirm the difference in the experimental results corroborated by the Cook-Gordon mechanism. The findings from the cohesive zone simulation provide deeper insights into soft microinterlock fracture mechanics that could prominently help in the rational designing of sutureless skin grafts and electronic skin.
%R 10.1103/PhysRevE.102.012801
%@ 1063-651X


%0 Journal Article
%T Initial assessment of monocrystalline silicon solar cells as large-area sensors for precise flux calibration
%A Brownsberger, Sasha
%A Mondrik, Nicholas
%A Stubbs, Christopher W.
%+ AA(Harvard University, Department of Physics, Cambridge, Massachusetts, United States), AB(Harvard University, Department of Physics, Cambridge, Massachusetts, United States), AC(Harvard University, Department of Astronomy, Cambridge, Massachusetts, United States)
%J Journal of Astronomical Telescopes, Instruments, and Systems
%V 6
%D 2020
%8 April 01, 2020
%P 026001
%K Astrophysics - Instrumentation and Methods for Astrophysics; Physics
- Applied Physics
%U https://ui.adsabs.harvard.edu/abs/2020JATIS...6b6001B
%X As the precision frontier of large-area survey astrophysics advances toward the one millimagnitude level, flux calibration of astronomical instrumentation remains an ongoing challenge. We describe initial testing of silicon solar cells (SCs) as large-aperture precise calibration photodiodes. We present measurements of dark current, linearity, frequency response, spatial response uniformity, and noise characteristics of the Sunpower C60 SCs, an interdigitated back-contact 125 × 125 mm<SUP>2</SUP> monocrystalline SC. We find that these devices may hold promise as large-area flux calibration sensors and that further analyses over a broader range of operating conditions are necessary.
%R 10.1117/1.JATIS.6.2.026001
%= eprint: arXiv:1909.13346


%0 Conference Paper
%T The Value of Being There: Toward a Science of Immersive Virtual Field Trips
%A Klippel, A.
%A Zhao, J.
%A Wallgruen, J. O.
%A Oprean, D.
%A Stubbs, C.
%A Jackson, K. L.
%A La Femina, P. C.
%+ AA(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AB(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AC(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AD(University of Missouri, Columbia, MO, United States), AE(Teaching and Learning with Technology, Pennsylvania State University Main Campus, University Park, PA, United States), AF(Teaching and Learning with Technology, Pennsylvania State University Main Campus, University Park, PA, United States), AG(Department of Geosciences, Pennsylvania State University Main Campus, University Park, PA, United States)
%J AGU Fall Meeting Abstracts
%V 2018
%D 2018
%8 December 01, 2018
%P ED54B-07
%K 0810 Post-secondary education; EDUCATIONDE: 0825 Teaching methods;
EDUCATIONDE: 0845 Instructional tools; EDUCATIONDE: 0850 Geoscience
education research; EDUCATION
%U https://ui.adsabs.harvard.edu/abs/2018AGUFMED54B..07K
%X The democratization of immersive experiences both from a perspective of creating them and of accessing them requires and allows for thinking about scientific, evidence-based design principles for immersive learning. Immersive learning has the potential to paradigmatically change place-based learning and as such touches the very core of earth sciences. To foster the empirical grounding of immersive learning, we detail a series of empirical evaluations of a geosciences field trip, common in undergraduate education across numerous disciplines. We conducted two studies so far that build on a previously proposed research framework in which we developed a basic taxonomy of virtual field trips distinguishing between basic, plus, and advanced experiences. The empirical evaluations draw a picture of the value of immersive experiences as a supplement and potentially proxy of actual field trips and how immersive technologies allow for enhancing (virtual) field trip experiences that are otherwise not possible. Results show an overwhelmingly positive response of students to virtual field trips with significantly higher valued learning experience and enjoyment. Furthermore, the introduction of pseudo-aerial imagery shows a significant improvement of the participants spatial situation model. As contextualizing and spatially grounding is essential for place-based learning experiences, plus versions of virtual field trips have the potential to add value to the learning outcome and immersive virtual field trip experience. We discuss the positive results as well as critical feedback such as the absence of touch in virtual experiences and lay out our vision for the future of immersive learning experiences across the earth sciences.


%0 Conference Proceedings
%T Testing of the LSST's photometric calibration strategy at the CTIO 0.9 meter telescope
%A Coughlin, Michael W.
%A Deustua, Susana
%A Guyonnet, Augustin
%A Mondrik, Nicholas
%A Rice, Joseph P.
%A Stubbs, Christopher W.
%A Woodward, John T.
%+ AA(Caltech (United States)), AB(Space Telescope Science Institute (United States)), AC(Harvard Univ. (United States)), AD(Harvard Univ. (United States)), AE(National Institute of Standards and Technology (United States)), AF(Harvard Univ. (United States)), AG(National Institute of Standards and Technology (United States))
%J Observatory Operations: Strategies, Processes, and Systems VII
%V 10704
%D 2018
%8 July 01, 2018
%P 1070420
%K Astrophysics - Instrumentation and Methods for Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2018SPIE10704E..20C
%X The calibration hardware system of the Large Synoptic Survey Telescope (LSST) is designed to measure two quantities: a telescope's instrumental response function versus wavelength and atmospheric transmission. First of all, a "collimated beam projector," which projects monochromatic light, monitored with a NIST-traceable photodiode, through a mask and a collimating optic onto the telescope, is designed to measure the instrumental response function. This method does not suffer from stray light effects and the reflections/ghosting present when using a flat-field screen illumination, which has a systematic source of uncertainty from uncontrolled reflections. It allows for an independent measurement of the throughput of the telescope's optical train as well as each filter's transmission as a function of position on the primary mirror. Second, CALSPEC stars can be used as calibrated light sources to illuminate the atmosphere and measure its transmission. To produce spectrophotometry necessary to measure the atmosphere's transfer function, we use the telescope's imager with a Ronchi grating in place of a filter to configure it as a low resolution slitless spectrograph. In this paper, we describe this calibration strategy, focusing on results from this prototype system at the Cerro Tololo Inter-American Observatory (CTIO) 0.9 meter telescope. We compare the instrumental throughput measurements to nominal values from the vendor. We describe measurements of the atmosphere made via CALSPEC standard stars during the same run.
%R 10.1117/12.2309582
%= eprint: arXiv:1806.02422


%0 Journal Article
%T Monitoring photo-induced population dynamics in metastable linkage isomer crystals: a crystallographic kinetic study of [Pd(Bu4dien)NO2]BPh4
%A Hatcher, Lauren E.
%A Skelton, Jonathan M.
%A Warren, Mark R.
%A Stubbs, Clare
%A da Silva, E. Lora
%A Raithby, Paul R.
%J Physical Chemistry Chemical Physics (Incorporating Faraday Transactions)
%V 20
%D 2018
%8 January 01, 2018
%P 5874
%U https://ui.adsabs.harvard.edu/abs/2018PCCP...20.5874H
%R 10.1039/C7CP05422J
%@ 1463-9076


%0 Journal Article
%T An absolute calibration system for millimeter-accuracy APOLLO measurements
%A Adelberger, E. G.
%A Battat, J. B. R.
%A Birkmeier, K. J.
%A Colmenares, N. R.
%A Davis, R.
%A Hoyle, C. D.
%A Huang, L. R.
%A McMillan, R. J.
%A Murphy, T. W., Jr.
%A Schlerman, E.
%A Skrobol, C.
%A Stubbs, C. W.
%A Zach, A.
%+ AA(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, United States of America), AB(Department of Physics, Wellesley College, 106 Central St, Wellesley, MA 02481, United States of America), AC(TOPTICA Photonics AG, Lochhamer Schlag 19, 82166 Graefelfing/Munich, Germany), AD(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, United States of America), AE(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, United States of America), AF(Department of Physics and Astronomy, Humboldt State University, One Harpst St, Arcata, CA 95521-8299, United States of America), AG(Department of Physics, Wellesley College, 106 Central St, Wellesley, MA 02481, United States of America), AH(Apache Point Observatory, 2001 Apache Point Rd, Sunspot, NM 88349-0059, United States of America), AI(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, United States of America), AJ(Department of Physics, Wellesley College, 106 Central St, Wellesley, MA 02481, United States of America), AK(TOPTICA Photonics AG, Lochhamer Schlag 19, 82166 Graefelfing/Munich, Germany), AL(Department of Physics, Harvard University, 17 Oxford St, Cambridge, MA 02318, United States of America), AM(TOPTICA Photonics AG, Lochhamer Schlag 19, 82166 Graefelfing/Munich, Germany)
%J Classical and Quantum Gravity
%V 34
%D 2017
%8 December 01, 2017
%P 245008
%K Astrophysics - Instrumentation and Methods for Astrophysics; General
Relativity and Quantum Cosmology
%U https://ui.adsabs.harvard.edu/abs/2017CQGra..34x5008A
%X Lunar laser ranging provides a number of leading experimental tests of gravitation—important in our quest to unify general relativity and the standard model of physics. The apache point observatory lunar laser-ranging operation (APOLLO) has for years achieved median range precision at the  ∼2 mm level. Yet residuals in model-measurement comparisons are an order-of-magnitude larger, raising the question of whether the ranging data are not nearly as accurate as they are precise, or if the models are incomplete or ill-conditioned. This paper describes a new absolute calibration system (ACS) intended both as a tool for exposing and eliminating sources of systematic error, and also as a means to directly calibrate ranging data in situ. The system consists of a high-repetition-rate (80 MHz) laser emitting short (&lt; 10 ps) pulses that are locked to a cesium clock. In essence, the ACS delivers photons to the APOLLO detector at exquisitely well-defined time intervals as a ‘truth’ input against which APOLLO’s timing performance may be judged and corrected. Preliminary analysis indicates no inaccuracies in APOLLO data beyond the  ∼3 mm level, suggesting that historical APOLLO data are of high quality and motivating continued work on model capabilities. The ACS provides the means to deliver APOLLO data both accurate and precise below the 2 mm level.
%R 10.1088/1361-6382/aa953b
%= eprint: arXiv:1706.09550
%@ 0264-9381


%0 Conference Paper
%T Immersive Virtual Reality Field Trips in the Geosciences: Integrating Geodetic Data in Undergraduate Geoscience Courses
%A La Femina, P. C.
%A Klippel, A.
%A Zhao, J.
%A Walgruen, J. O.
%A Stubbs, C.
%A Jackson, K. L.
%A Wetzel, R.
%+ AA(Pennsylvania State University Main Campus, University Park, PA, United States), AB(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AC(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AD(Geography, Pennsylvania State University Main Campus, University Park, PA, United States), AE(Teaching and Learning with Technology, Pennsylvania State University Main Campus, University Park, PA, United States), AF(Teaching and Learning with Technology, Pennsylvania State University Main Campus, University Park, PA, United States), AG(Teaching and Learning with Technology, Pennsylvania State University Main Campus, University Park, PA, United States)
%J AGU Fall Meeting Abstracts
%V 2017
%D 2017
%8 December 01, 2017
%P ED11B-0128
%K 0810 Post-secondary education; EDUCATION; 0820 Curriculum and
laboratory design; EDUCATION; 0825 Teaching methods; EDUCATION
%U https://ui.adsabs.harvard.edu/abs/2017AGUFMED11B0128L
%X High-quality geodetic data and data products, including GPS-GNSS, InSAR, LiDAR, and Structure from Motion (SfM) are opening the doors to visualizing, quantifying, and modeling geologic, tectonic, geomorphic, and geodynamic processes. The integration of these data sets with other geophysical, geochemical and geologic data is providing opportunities for the development of immersive Virtual Reality (iVR) field trips in the geosciences. iVR fieldtrips increase accessibility in the geosciences, by providing experiences that allow for: 1) exploration of field locations that might not be tenable for introductory or majors courses; 2) accessibility to outcrops for students with physical disabilities; and 3) the development of online geosciences courses. We have developed a workflow for producing iVR fieldtrips and tools to make quantitative observations (e.g., distance, area, and volume) within the iVR environment. We use a combination of terrestrial LiDAR and SfM data, 360° photos and videos, and other geophysical, geochemical and geologic data to develop realistic experiences for students to be exposed to the geosciences from sedimentary geology to physical volcanology. We present two of our iVR field trips: 1) Inside the Volcano: Exploring monogenetic volcanism at Thrihnukagigar Iceland; and 2) Changes in Depositional Environment in a Sedimentary Sequence: The Reedsville and Bald Eagle Formations, Pennsylvania. The Thrihnukagigar experience provides the opportunity to investigate monogenetic volcanism through the exploration of the upper 125 m of a fissure-cinder cone eruptive system. Students start at the plate boundary scale, then zoom into a single volcano where they can view the 3D geometry from either terrestrial LiDAR or SfM point clouds, view geochemical data and petrologic thins sections of rock samples, and a presentation of data collection and analysis, results and interpretation. Our sedimentary geology experience is based on a field lab from our introductory Physical Geology course for majors in Geoscience and Engineering. The lab explores formation of a turbidite sequence, and the transition to a shallower marine environment using the tools described above and data from SfM and 360° photos. We are evaluating the effectiveness of both iVR field trips on student learning.


%0 Conference Proceedings
%T High fidelity point-spread function retrieval in the presence of electrostatic, hysteretic pixel response
%A Rasmussen, Andrew
%A Guyonnet, Augustin
%A Lage, Craig
%A Antilogus, Pierre
%A Astier, Pierre
%A Doherty, Peter
%A Gilmore, Kirk
%A Kotov, Ivan
%A Lupton, Robert
%A Nomerotski, Andrei
%A O'Connor, Paul
%A Stubbs, Christopher
%A Tyson, Anthony
%A Walter, Christopher
%+ AA(SLAC National Accelerator Lab. (United States)), AB(LPHNE/IN2P3/CNRS, UPMC (France)), AC(Univ. of California, Davis (United States)), AD(LPHNE/IN2P3/CNRS, UPMC (France)), AE(LPHNE/IN2P3/CNRS, UPMC (France)), AF(Harvard Univ. (United States)), AG(SLAC National Accelerator Lab. (United States)), AH(Brookhaven National Lab. (United States)), AI(Princeton Univ. (United States)), AJ(Brookhaven National Lab. (United States)), AK(Brookhaven National Lab. (United States)), AL(Harvard Univ. (United States)), AM(Univ. of California, Davis (United States)), AN(Duke Univ. (United States))
%J High Energy, Optical, and Infrared Detectors for Astronomy VII
%V 9915
%D 2016
%8 August 01, 2016
%P 99151A
%K Astrophysics - Instrumentation and Methods for Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9915E..1AR
%X We employ electrostatic conversion drift calculations to match CCD pixel signal covariances observed in at field exposures acquired using candidate sensor devices for the LSST Camera.<SUP>1, 2</SUP> We thus constrain pixel geometry distortions present at the end of integration, based on signal images recorded. We use available data from several operational voltage parameter settings to validate our understanding. Our primary goal is to optimize flux point spread function (FPSF) estimation quantitatively, and thereby minimize sensor-induced errors which may limit performance in precision astronomy applications. We consider alternative compensation scenarios that will take maximum advantage of our understanding of this underlying mechanism in data processing pipelines currently under development. To quantitatively capture the pixel response in high-contrast/high dynamic range operational extrema, we propose herein some straightforward laboratory tests that involve altering the time order of source illumination on sensors, within individual test exposures. Hence the word hysteretic in the title of this paper.
%R 10.1117/12.2234482
%= eprint: arXiv:1608.01964
%@ 0277-786X


%0 Conference Proceedings
%T The LSST calibration hardware system design and development
%A Ingraham, Patrick
%A Stubbs, Christopher W.
%A Claver, Charles
%A Lupton, Robert
%A Araujo, Constanza
%A Liang, Ming
%A Andrew, John
%A Barr, Jeff
%A Brannon, Kairn
%A Coughlin, Michael
%A Fisher-Lavine, Merlin
%A Gressler, William
%A Sebag, Jacques
%A Thomas, Sandrine
%A Wiecha, Oliver
%A Yoachim, Peter
%+ AA(Large Synoptic Survey Telescope (United States)), AB(Harvard Univ. (United States)), AC(Large Synoptic Survey Telescope (United States)), AD(Princeton Univ. (United States)), AE(Large Synoptic Survey Telescope (United States)), AF(Large Synoptic Survey Telescope (United States)), AG(Large Synoptic Survey Telescope (United States)), AH(Large Synoptic Survey Telescope (United States)), AI(Harvard Univ. (United States)), AJ(Harvard Univ. (United States)), AK(Princeton Univ. (United States)), AL(Large Synoptic Survey Telescope (United States)), AM(Large Synoptic Survey Telescope (United States)), AN(Large Synoptic Survey Telescope (United States)), AO(Large Synoptic Survey Telescope (United States)), AP(Univ. of Washington (United States))
%J Ground-based and Airborne Telescopes VI
%V 9906
%D 2016
%8 August 01, 2016
%P 99060O
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9906E..0OI
%X The Large Synoptic Survey Telescope (LSST) is currently under construction and upon completion will perform precision photometry over the visible sky at a 3-day cadence. To meet the stringent relative photometry goals, LSST will employ multiple calibration systems to measure and compensate for systematic errors. This paper describes the design and development of these systems including: a dedicated calibration telescope and spectrograph to measure the atmospheric transmission function, a collimated beam projector to characterize the spatial dependence of the LSST transmission function and an at-field screen illumination system to measure the high-frequency variations in the global system response function.
%R 10.1117/12.2233404
%@ 0277-786X


%0 Conference Proceedings
%T Integrated system tests of the LSST raft tower modules
%A O'Connor, P.
%A Antilogus, P.
%A Doherty, P.
%A Haupt, J.
%A Herrmann, S.
%A Huffer, M.
%A Juramy-Giles, C.
%A Kuczewski, J.
%A Russo, S.
%A Stubbs, C.
%A Van Berg, R.
%+ AA(Brookhaven National Lab. (United States)), AB(Lab. de Physique Nucléaire et des Hautes Énergies (France)), AC(Harvard Univ. (United States)), AD(Brookhaven National Lab. (United States)), AE(SLAC National Accelerator Lab. (United States)), AF(SLAC National Accelerator Lab. (United States)), AG(Lab. de Physique Nucléaire et des Hautes Énergies (France)), AH(Brookhaven National Lab. (United States)), AI(SLAC National Accelerator Lab. (France)), AJ(Harvard Univ. (United States)), AK(Univ. of Pennsylvania (United States))
%J High Energy, Optical, and Infrared Detectors for Astronomy VII
%V 9915
%D 2016
%8 July 01, 2016
%P 99150X
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9915E..0XO
%X The science focal plane of the LSST camera is made up of 21 fully autonomous 144 Mpixel imager units designated raft tower modules (RTM). These imagers incorporate nine 4K x 4K fully-depleted CCDs and 144 channels of readout electronics, including a dedicated CMOS video processing ASIC and components that provide CCD biasing and clocking, video digitization, thermal stabilization, and a high degree of monitoring and telemetry. The RTM achieves its performance goals for readout speed, read noise, linearity, and crosstalk with a power budget of less than 400mW/channel. Series production is underway on the first units and the production will run until 2018. We present the RTM final design, tests of the integrated signal chain, and performance results for the fully-integrated module with pre-production CCDs.
%R 10.1117/12.2232729
%@ 0277-786X


%0 Conference Proceedings
%T An optical to IR sky brightness model for the LSST
%A Yoachim, Peter
%A Coughlin, Michael
%A Angeli, George Z.
%A Claver, Charles F.
%A Connolly, Andrew J.
%A Cook, Kem
%A Daniel, Scott
%A Ivezić, Željko
%A Jones, R. Lynne
%A Petry, Catherine
%A Reuter, Michael
%A Stubbs, Christopher
%A Xin, Bo
%+ AA(Univ. of Washington (United States)), AB(Harvard Univ. (United States)), AC(LSST Project Office (United States)), AD(LSST Project Office (United States)), AE(Univ. of Washington (United States)), AF(Cook Astronomical Consulting (United States)), AG(Univ. of Washington (United States)), AH(Univ. of Washington (United States)), AI(Univ. of Washington (United States)), AJ(LSST Project Office (United States)), AK(LSST Project Office (United States)), AL(Harvard Univ. (United States)), AM(LSST Project Office (United States))
%J Observatory Operations: Strategies, Processes, and Systems VI
%V 9910
%D 2016
%8 July 01, 2016
%P 99101A
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9910E..1AY
%X To optimize the observing strategy of a large survey such as the LSST, one needs an accurate model of the night sky emission spectrum across a range of atmospheric conditions and from the near-UV to the near-IR. We have used the ESO SkyCalc Sky Model Calculator<SUP>1, 2</SUP> to construct a library of template spectra for the Chilean night sky. The ESO model includes emission from the upper and lower atmosphere, scattered starlight, scattered moonlight, and zodiacal light. We have then extended the ESO templates with an empirical fit to the twilight sky emission as measured by a Canon all-sky camera installed at the LSST site. With the ESO templates and our twilight model we can quickly interpolate to any arbitrary sky position and date and return the full sky spectrum or surface brightness magnitudes in the LSST filter system. Comparing our model to all-sky observations, we find typical residual RMS values of +/-0.2-0.3 magnitudes per square arcsecond.
%R 10.1117/12.2232947
%@ 0277-786X


%0 Conference Proceedings
%T Feature-based telescope scheduler
%A Naghib, Elahesadat
%A Vanderbei, Robert J.
%A Stubbs, Christopher
%+ AA(Princeton Univ. (United States)), AB(Princeton Univ. (United States)), AC(Harvard Univ. (United States))
%J Observatory Operations: Strategies, Processes, and Systems VI
%V 9910
%D 2016
%8 July 01, 2016
%P 991011
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9910E..11N
%X Feature-based Scheduler offers a sequencing strategy for ground-based telescopes. This scheduler is designed in the framework of Markovian Decision Process (MDP), and consists of a sub-linear online controller, and an offline supervisory control-optimizer. Online control law is computed at the moment of decision for the next visit, and the supervisory optimizer trains the controller by simulation data. Choice of the Differential Evolution (DE) optimizer, and introducing a reduced state space of the telescope system, offer an efficient and parallelizable optimization algorithm. In this study, we applied the proposed scheduler to the problem of Large Synoptic Survey Telescope (LSST). Preliminary results for a simplified model of LSST is promising in terms of both optimality, and computational cost.
%R 10.1117/12.2232053
%@ 0277-786X


%0 Conference Proceedings
%T A collimated beam projector for precise telescope calibration
%A Coughlin, Michael
%A Abbott, T. M. C.
%A Brannon, Kairn
%A Claver, Chuck
%A Doherty, Peter
%A Fisher-Levine, Merlin
%A Ingraham, Patrick
%A Lupton, Robert
%A Mondrik, Nicholas
%A Stubbs, Christopher
%+ AA(Harvard Univ. (United States)), AB(Cerro Tololo Inter-American Observatory (Chile)), AC(Harvard Univ. (United States)), AD(Large Synoptic Survey Telescope (United States)), AE(Harvard Univ. (United States)), AF(Brookhaven National Lab. (United States)), AG(Large Synoptic Survey Telescope (United States)), AH(Princeton Univ. (United States)), AI(Harvard Univ. (United States)), AJ(Harvard Univ. (United States))
%J Observatory Operations: Strategies, Processes, and Systems VI
%V 9910
%D 2016
%8 July 01, 2016
%P 99100V
%K Astrophysics - Instrumentation and Methods for Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2016SPIE.9910E..0VC
%X The precise determination of the instrumental response function versus wavelength is a central ingredient in contemporary photometric calibration strategies. This typically entails propagating narrowband illumination through the system pupil, and comparing the detected photon rate across the focal plane to the amount of incident light as measured by a calibrated photodiode. However, stray light effects and reflections/ghosting (especially on the edges of filter passbands) in the optical train constitute a major source of systematic uncertainty when using a at-field screen as the illumination source. A collimated beam projector that projects a mask onto the focal plane of the instrument can distinguish focusing light paths from stray and scattered light, allowing for a precise determination of instrumental throughput. This paper describes the conceptual design of such a system, outlines its merits, and presents results from a prototype system used with the Dark Energy Camera wide field imager on the 4-meter Blanco telescope. A calibration scheme that blends results from at-field images with collimated beam projector data to obtain the equivalent of an illumination correction at high spectral and angular resolution is also presented. In addition to providing a precise system throughput calibration, by monitoring the evolution of the intensity and behaviour of the ghosts in the optical system, the collimated beam projector can be used to track the evolution of the filter transmission properties and various anti-reflective coatings in the optical system.
%R 10.1117/12.2231677
%= eprint: arXiv:1805.05867
%@ 0277-786X


%0 Journal Article
%T Precise astronomical flux calibration and its impact on studying the nature of the dark energy
%A Stubbs, Christopher W.
%A Brown, Yorke J.
%+ AA(Department of Physics and Department of Astronomy, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA), AB(Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755, USA)
%J Modern Physics Letters A
%V 30
%D 2015
%8 December 01, 2015
%P 1530030
%K Instrumentation: detectors; methods: data analysis; techniques: image
processing; 04.00.00; 95.00.00; General relativity and gravitation;
Fundamental astronomy and astrophysics; instrumentation techniques and
astronomical observations; Astrophysics - Instrumentation and Methods
for Astrophysics; Astrophysics - Cosmology and Nongalactic Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2015MPLA...3030030S
%X Measurements of the luminosity of Type Ia supernovae versus redshift provided the original evidence for the accelerating expansion of the Universe and the existence of dark energy. Despite substantial improvements in survey methodology, systematic uncertainty in flux calibration dominates the error budget for this technique, exceeding both statistics and other systematic uncertainties. Consequently, any further collection of Type Ia supernova data will fail to refine the constraints on the nature of dark energy unless we also improve the state of the art in astronomical flux calibration to the order of 1%. We describe how these systematic errors arise from calibration of instrumental sensitivity, atmospheric transmission and Galactic extinction, and discuss ongoing efforts to meet the 1% precision challenge using white dwarf stars as celestial standards, exquisitely calibrated detectors as fundamental metrologic standards, and real-time atmospheric monitoring.
%R 10.1142/S021773231530030X
%= eprint: arXiv:1601.04052
%@ 0217-7323


%0 Conference Proceedings
%T Comparison of MODTRAN5 atmospheric extinction predictions with narrowband astronomical flux observations
%A Stubbs, Christopher W.
%A Vaz, Amali
%A Fraser, Gerald T.
%A Cramer, Claire E.
%A Lykke, Keith R.
%A Woodward, John T.
%+ AA(Harvard Univ. (United States)), AB(Harvard Univ. (United States)), AC(National Institute of Standards and Technology (United States)), AD(National Institute of Standards and Technology (United States)), AE(National Institute of Standards and Technology (United States)), AF(National Institute of Standards and Technology (United States))
%J Infrared Remote Sensing and Instrumentation XXIII
%V 9608
%D 2015
%8 September 01, 2015
%P 96080R
%U https://ui.adsabs.harvard.edu/abs/2015SPIE.9608E..0RS
%X Improving the precision of ground-based astronomical observations is an objective of both current (e.g. PanSTARRS1) and future (e.g. Dark Energy Survey and the Large Synoptic Survey Telescope) sky surveys. An important element of this effort is to determine the optical attenuation imposed by the atmosphere. We have obtained atmospheric extinction observations from narrowband photometry (typically 10 nm bandwidth) at central wavelengths of 380 nm, 488 nm, 500 nm, 585 nm, 656 nm, 675 nm and 840 nm. The passbands were selected to measure the continuum component (predominantly from Rayleigh and aerosol scattering) of atmospheric attenuation, and to avoid molecular absorption features in the atmosphere. We compare these atmospheric extinction observations with predictions from MODTRAN5, a commonly used computer model of atmospheric optical transmission. The MODTRAN5 calculations were informed by a satellite-based determination of atmospheric ozone on the night of observations. We also adjusted the MODTRAN5 predictions of Rayleigh scattering to account for the difference between the default pressure and that measured at the observatory on the night of observations. We find excellent agreement across all passbands between the pressureadjusted MODTRAN5 extinction model and the observations, within our typical extinction uncertainty of 0.013 mag/airmass, but only if we exclude any aerosol scattering component in the MODTRAN5 model. Even though this is a very limited test, with observations of a single star for a single night, the fact that we obtain excellent agreement between extinction measurements and the MODTRAN5 model, with no adjustable fit parameters, bodes well for exploiting MODTRAN5 to increase the precision of ground-based flux measurements.
%R 10.1117/12.2188453
%@ 0277-786X


%0 Journal Article
%T Real-time earthquake warning for astronomical observatories
%A Coughlin, Michael
%A Stubbs, Christopher
%A Barrientos, Sergio
%A Claver, Chuck
%A Harms, Jan
%A Chris Smith, R.
%A Warner, Michael
%+ AA(Department of Physics, Harvard University, Cambridge, MA, USA), AB(Department of Physics, Harvard University, Cambridge, MA, USA), AC(Centro Sismológico Nacional de la Universidad de Chile, Santiago, Chile), AD(LSST Observatory, Tucson, AZ, USA), AE(INFN, Sezione di Firenze, Sesto Fiorentino, Italy), AF(Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, La Serena, Chile), AG(Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, La Serena, Chile)
%J Experimental Astronomy
%V 39
%D 2015
%8 June 01, 2015
%P 387
%K Astronomical observatories; Earthquakes; Gravitational-wave
detectors; Astrophysics - Instrumentation and Methods for Astrophysics;
Physics - Geophysics
%U https://ui.adsabs.harvard.edu/abs/2015ExA....39..387C
%X Early earthquake warning is a rapidly developing capability that has significant ramifications for many fields, including astronomical observatories. In this work, we describe the susceptibility of astronomical facilities to seismic events, including large telescopes as well as second-generation ground-based gravitational-wave interferometers. We describe the potential warning times for observatories from current seismic networks and propose locations for future seismometers to maximize warning times.
%R 10.1007/s10686-015-9454-1
%= eprint: arXiv:1412.3603
%@ 0922-6435


%0 Conference Proceedings
%T A framework for modeling the detailed optical response of thick, multiple segment, large format sensors for precision astronomy applications
%A Rasmussen, Andrew
%A Antilogus, Pierre
%A Astier, Pierre
%A Claver, Chuck
%A Doherty, Peter
%A Dubois-Felsmann, Gregory
%A Gilmore, Kirk
%A Kahn, Steven
%A Kotov, Ivan
%A Lupton, Robert
%A O'Connor, Paul
%A Nomerotski, Andrei
%A Ritz, Steve
%A Stubbs, Christopher
%+ AA(SLAC National Accelerator Lab. (United States)), AB(LPNHE/IN2P3, CNRS, Univ. Pierre et Marie Curie (France)), AC(LPNHE/IN2P3, CNRS, Univ. Pierre et Marie Curie (France)), AD(National Optical Astronomy Observatory (United States)), AE(Harvard Univ. (United States)), AF(SLAC National Accelerator Lab. (United States)), AG(SLAC National Accelerator Lab. (United States)), AH(SLAC National Accelerator Lab. (United States)), AI(Brookhaven National Lab. (United States)), AJ(Princeton Univ. (United States)), AK(Brookhaven National Lab. (United States)), AL(Brookhaven National Lab. (United States)), AM(Univ. of California, Santa Cruz (United States)), AN(Harvard Univ. (United States))
%J Modeling, Systems Engineering, and Project Management for Astronomy VI
%V 9150
%D 2014
%8 August 01, 2014
%P 915017
%K Astrophysics - Instrumentation and Methods for Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2014SPIE.9150E..17R
%X Near-future astronomical survey experiments, such as LSST, possess system requirements of unprecedented fidelity that span photometry, astrometry and shape transfer. Some of these requirements flow directly to the array of science imaging sensors at the focal plane. Availability of high quality characterization data acquired in the course of our sensor development program has given us an opportunity to develop and test a framework for simulation and modeling that is based on a limited set of physical and geometric effects. In this paper we describe those models, provide quantitative comparisons between data and modeled response, and extrapolate the response model to predict imaging array response to astronomical exposure. The emergent picture departs from the notion of a fixed, rectilinear grid that maps photo-conversions to the potential well of the channel. In place of that, we have a situation where structures from device fabrication, local silicon bulk resistivity variations and photo-converted carrier patterns still accumulating at the channel, together influence and distort positions within the photosensitive volume that map to pixel boundaries. Strategies for efficient extraction of modeling parameters from routinely acquired characterization data are described. Methods for high fidelity illumination/image distribution parameter retrieval, in the presence of such distortions, are also discussed.
%R 10.1117/12.2057411
%= eprint: arXiv:1407.5655
%@ 0277-786X


%0 Conference Proceedings
%T The guider and wavefront curvature sensor subsystem for the Large Synoptic Survey Telescope
%A Riot, Vincent J.
%A Arndt, Kirk
%A Claver, Chuck
%A Doherty, Peter E.
%A Gilmore, D. K.
%A Hascall, Patrick A.
%A Herrmann, Sven
%A Kotov, Ivan
%A O'Connor, Paul
%A Sebag, Jacques
%A Stubbs, Christopher W.
%A Warner, Michael
%+ AA(Lawrence Livermore National Lab. (United States)), AB(Purdue Univ. (United States)), AC(Large Synoptic Survey Telescope (United States)), AD(Harvard Univ. (United States)), AE(SLAC National Accelerator Lab. (United States)), AF(SLAC National Accelerator Lab. (United States)), AG(SLAC National Accelerator Lab. (United States)), AH(Brookhaven National Lab. (United States)), AI(Brookhaven National Lab. (United States)), AJ(Large Synoptic Survey Telescope (United States)), AK(Harvard Univ. (United States)), AL(Cerro Tololo Inter-American Observatory (Chile))
%J Ground-based and Airborne Instrumentation for Astronomy V
%V 9147
%D 2014
%8 August 01, 2014
%P 914774
%U https://ui.adsabs.harvard.edu/abs/2014SPIE.9147E..74R
%X The Large Synoptic Survey Telescope instrument include four guiding and wavefront sensing subsystems called corner raft subsystems, in addition to the main science array of 189 4K x 4K CCDs. These four subsystems are placed at the four corners of the instrumented field of view. Each wavefront/guiding subsystem comprises a pair of 4K x 4K guide sensors, capable of producing 9 frames/second, and a pair of offset 2K x 4K wavefront curvature sensors from which the images are read out at the cadence of the main camera system, providing 15 sec integrations. These four guider/wavefront corner rafts are mechanically and electrically isolated from the science sensor rafts and can be installed or removed independently from any other focal plane subsystem. We present the implementation of this LSST subsystem detailing both hardware and software development and status.
%R 10.1117/12.2056605
%@ 0277-786X


%0 Conference Proceedings
%T Electro-optical testing of fully depleted CCD image sensors for the Large Synoptic Survey Telescope camera
%A Doherty, Peter E.
%A Antilogus, Pierre
%A Astier, Pierre
%A Chiang, James
%A Gilmore, D. Kirk
%A Guyonnet, Augustin
%A Huang, Dajun
%A Kelly, Heather
%A Kotov, Ivan
%A Kubanek, Petr
%A Nomerotski, Andrei
%A O'Connor, Paul
%A Rasmussen, Andrew
%A Riot, Vincent J.
%A Stubbs, Christopher W.
%A Takacs, Peter
%A Tyson, J. Anthony
%A Vetter, Kurt
%+ AA(Harvard Univ. (United States)), AB(Institut National de Physique Nucléaire et de Physique des Particules (France)), AC(Institut National de Physique Nucléaire et de Physique des Particules (France)), AD(SLAC National Accelerator Lab. (United States)), AE(SLAC National Accelerator Lab. (United States)), AF(Institut National de Physique Nucléaire et de Physique des Particules (France)), AG(Brookhaven National Lab. (United States)), AH(SLAC National Accelerator Lab. (United States)), AI(Brookhaven National Lab. (United States)), AJ(Institute of Physics of the ASCR, v.v.i. (Czech Republic)), AK(Brookhaven National Lab. (United States)), AL(Brookhaven National Lab. (United States)), AM(SLAC National Accelerator Lab. (United States)), AN(Lawrence Livermore National Lab. (United States)), AO(Harvard Univ. (United States)), AP(Brookhaven National Lab. (United States)), AQ(Univ. of California, Davis (United States)), AR(Brookhaven National Lab. (United States))
%J High Energy, Optical, and Infrared Detectors for Astronomy VI
%V 9154
%D 2014
%8 July 01, 2014
%P 915418
%U https://ui.adsabs.harvard.edu/abs/2014SPIE.9154E..18D
%X The LSST Camera science sensor array will incorporate 189 large format Charge Coupled Device (CCD) image sensors. Each CCD will include over 16 million pixels and will be divided into 16 equally sized segments and each segment will be read through a separate output amplifier. The science goals of the project require CCD sensors with state of the art performance in many aspects. The broad survey wavelength coverage requires fully depleted, 100 micrometer thick, high resistivity, bulk silicon as the imager substrate. Image quality requirements place strict limits on the image degradation that may be caused by sensor effects: optical, electronic, and mechanical. In this paper we discuss the design of the prototype sensors, the hardware and software that has been used to perform electro-optic testing of the sensors, and a selection of the results of the testing to date. The architectural features that lead to internal electrostatic fields, the various effects on charge collection and transport that are caused by them, including charge diffusion and redistribution, effects on delivered PSF, and potential impacts on delivered science data quality are addressed.
%R 10.1117/12.2056733
%@ 0277-786X


%0 Conference Proceedings
%T PISCO: the Parallel Imager for Southern Cosmology Observations
%A Stalder, Brian
%A Stark, Antony A.
%A Amato, Stephen M.
%A Geary, John
%A Shectman, Stephen A.
%A Stubbs, Christopher W.
%A Szentgyorgyi, Andrew
%+ AA(Harvard-Smithsonian Ctr. for Astrophysics (United States)), AB(Harvard-Smithsonian Ctr. for Astrophysics (United States)), AC(Harvard-Smithsonian Ctr. for Astrophysics (United States)), AD(Harvard-Smithsonian Ctr. for Astrophysics (United States)), AE(Carnegie Observatories (United States)), AF(Harvard Univ. (United States)), AG(Harvard-Smithsonian Ctr. for Astrophysics (United States))
%J Ground-based and Airborne Instrumentation for Astronomy V
%V 9147
%D 2014
%8 July 01, 2014
%P 91473Y
%U https://ui.adsabs.harvard.edu/abs/2014SPIE.9147E..3YS
%X We present the design and lab performance of the Parallel Imager for Southern Cosmology Observations (PISCO), a photometer for the 6.5 m diameter Magellan telescopes that produces g<SUP>l</SUP>, r<SUP>l</SUP>, i<SUP>l</SUP>, and z<SUP>l</SUP> band images simulta- neously within a 9 arcminute field of view. This design provides efficient follow-up observations of faint sources, particularly galaxy clusters and supernovae. Simultaneous imaging speeds the observing cadence by at a factor of ~ 3 (including optical losses) compared to other photometric imagers. Also, the determination of color (flux ratio between bands) is relatively immune to time variations in gray opacity due to clouds, so observations can proceed in less than optimal conditions. First light is expected in September 2014 2014.
%R 10.1117/12.2054933
%@ 0277-786X


%0 Journal Article
%T Precision astronomy with imperfect fully depleted CCDs — an introduction and a suggested lexicon
%A Stubbs, C. W.
%+ AA(Department of Physics &amp; Department of Astronomy, Harvard University, 17 Oxford Street, Cambridge MA 02138, USA)
%J Journal of Instrumentation
%V 9
%D 2014
%8 March 01, 2014
%P C03032
%K Astrophysics - Instrumentation and Methods for Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2014JInst...9C3032S
%X This paper summarizes the introductory presentation for a workshop (held Nov 18, 19 2013 at Brookhaven National Laboratory) that explored the challenges associated with making precision astronomical measurements using deeply depleted = ``thick" =``high-ρ'' CCDs. While thick CCDs do provide definite advantages in terms of increased quantum efficiency at wavelengths 700 nm &lt; λ &lt; 1.1 μm and reduced fringing from atmospheric emission lines, these devices also exhibit undesirable features that pose a challenge to precision determination of the positions, fluxes, and shapes of astronomical objects, and for the precision extraction of features in astronomical spectra. For example, the assumptions of a perfectly rectilinear pixel grid and of an intensity-independent point spread function become increasingly invalid as we push to higher precision measurements. Many of the effects seen in these devices arise from lateral electrical fields within the detector, that produce charge transport anomalies that have been previously misinterpreted as quantum efficiency variations. Performing simplistic flat-fielding therefore introduces systematic errors in the image processing pipeline. One measurement challenge we face is devising a combination of calibration methods and algorithms that can distinguish genuine quantum efficiency variations from charge transport effects. These device imperfections also confront spectroscopic applications, such as line centroid determination for precision radial velocity studies. Given the scientific benefits of improving both the precision and accuracy of astronomical measurements, we need to identify, characterize, and overcome these various detector artifacts. In retrospect, many of the detector features first identified in thick CCDs also afflict measurements made with more traditional CCD detectors, albeit often at a reduced level since the photocharge is subject to the perturbing influence of lateral electric fields for a shorter time interval. I provide a qualitative overview of the physical effects we think are responsible for the observed device properties, and provide some perspective for the work that lies ahead. Finally, I take this opportunity to make a plea for establishing a clear and consistent vocabulary when describing these various detector features, and make some suggestions for a standard lexicon based on discussions at the workshop. A more refined understanding of the device imperfections we are working to circumvent lies ahead, and this workshop was convened to help us find our way.
%R 10.1088/1748-0221/9/03/C03032
%= eprint: arXiv:1312.2313


%0 Journal Article
%T Ebullition and storm-induced methane release from the East Siberian Arctic Shelf
%A Shakhova, Natalia
%A Semiletov, Igor
%A Leifer, Ira
%A Sergienko, Valentin
%A Salyuk, Anatoly
%A Kosmach, Denis
%A Chernykh, Denis
%A Stubbs, Chris
%A Nicolsky, Dmitry
%A Tumskoy, Vladimir
%A Gustafsson, Örjan
%+ AA(International Arctic Research Center, University of Alaska, Akasofu Building, Fairbanks, Alaska 99775-7320, USA; Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, 43 Baltiiskaya Street, Vladivostok 690041, Russia), AB(International Arctic Research Center, University of Alaska, Akasofu Building, Fairbanks, Alaska 99775-7320, USA; Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, 43 Baltiiskaya Street, Vladivostok 690041, Russia), AC(Marine Sciences Institute, University of California, Santa Barbara, California 93106, USA; Bubbleology Research International, Solvang, California 93463, USA), AD(Russian Academy of Sciences, Far Eastern Branch, Institute of Chemistry, 159, 100-Let Vladivostok Prospect, Vladivostok 690022, Russia), AE(Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, 43 Baltiiskaya Street, Vladivostok 690041, Russia), AF(Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, 43 Baltiiskaya Street, Vladivostok 690041, Russia), AG(Russian Academy of Sciences, Far Eastern Branch, Pacific Oceanological Institute, 43 Baltiiskaya Street, Vladivostok 690041, Russia), AH(Marine Sciences Institute, University of California, Santa Barbara, California 93106, USA), AI(Geophysical Institute, University of Alaska, 903 Koyukuk Drive, Fairbanks, Alaska 99775-7320, USA), AJ(Moscow State University, 1-12 Leninskie Gory, Moscow, Moscow 119991, Russia), AK(Department of Applied Environmental Science and Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden)
%J Nature Geoscience
%V 7
%D 2014
%8 January 01, 2014
%P 64
%U https://ui.adsabs.harvard.edu/abs/2014NatGe...7...64S
%X Vast quantities of carbon are stored in shallow Arctic reservoirs, such as submarine and terrestrial permafrost. Submarine permafrost on the East Siberian Arctic Shelf started warming in the early Holocene, several thousand years ago. However, the present state of the permafrost in this region is uncertain. Here, we present data on the temperature of submarine permafrost on the East Siberian Arctic Shelf using measurements collected from a sediment core, together with sonar-derived observations of bubble flux and measurements of seawater methane levels taken from the same region. The temperature of the sediment core ranged from -1.8 to 0°C. Although the surface layer exhibited the lowest temperatures, it was entirely unfrozen, owing to significant concentrations of salt. On the basis of the sonar data, we estimate that bubbles escaping the partially thawed permafrost inject 100-630mg methane m<SUP>-2</SUP>d<SUP>-1</SUP> into the overlying water column. We further show that water-column methane levels had dropped significantly following the passage of two storms. We suggest that significant quantities of methane are escaping the East Siberian Shelf as a result of the degradation of submarine permafrost over thousands of years. We suggest that bubbles and storms facilitate the flux of this methane to the overlying ocean and atmosphere, respectively.
%R 10.1038/ngeo2007


%0 Journal Article
%T Two-Photon Imaging of the Interaction of mTORC1 Components using Fluorescence Energy Transfer between Gfp-Expressing Proteins in a Spheroid Tumor Cell Model
%A Stubbs, Christopher D.
%A Scherer, Kathrin M.
%A Parker, Anthony W.
%A Weston, Eleanor C.
%A Botchway, Stanley W.
%J Biophysical Journal
%V 106
%D 2014
%8 January 01, 2014
%P 199a
%U https://ui.adsabs.harvard.edu/abs/2014BpJ...106R.199S
%R 10.1016/j.bpj.2013.11.1173
%@ 0006-3495


%0 Conference Paper
%T Implications of a warming Arctic - Methane emissions from submerged permafrost underlying the rapidly warming East Siberian Arctic Sea (Invited)
%A Leifer, I.
%A Shakhova, N. E.
%A Semiletov, I. P.
%A Yurganov, L.
%A Stubbs, C.
%+ AA(University of California, Santa Barbara, CA, USA;), AB(University of California, Santa Barbara, CA, USA;), AC(University of California, Santa Barbara, CA, USA;), AD(University of California, Santa Barbara, CA, USA;), AE(University of California, Santa Barbara, CA, USA;)
%J AGU Fall Meeting Abstracts
%V 2013
%D 2013
%8 December 01, 2013
%P B31I-01
%K 0428 BIOGEOSCIENCES Carbon cycling; 0312 ATMOSPHERIC COMPOSITION AND
STRUCTURE Air/sea constituent fluxes; 0702 CRYOSPHERE Permafrost; 1621
GLOBAL CHANGE Cryospheric change
%U https://ui.adsabs.harvard.edu/abs/2013AGUFM.B31I..01L
%X Methane (CH4) release from thawing Arctic permafrost is one of the few carbon-climate mechanisms that could change dramatically, forecast climate change in the near term. Submerged Arctic permafrost, such as underlies the vast East Siberian Arctic Sea (ESAS), is at particular risk due to rapidly warming oceans transferring heat to these deposits. Based on multibeam sonar surveys spanning thousands of kilometers, extensive methane bubble emissions across the ESAS have been documented. These bubble emissions are ubiquitous and in shallow water (&lt; 50 m) depositing a fraction of the escaping gas into the water column with the rest directly escaping to the air. Multibeam sonar data was analyzed to estimate ebullition fluxes for the ESAS and compared well with a mass balance estimate based on 'storm ventilation' mass budget measurements. Maps of the spatial distribution of ebullition emissions correlated with warm riverine input, suggesting a new positive feedback system between warming climate and methane emissions. These inputs are mirrored in satellite methane column data.


%0 Conference Proceedings
%T Tunable laser techniques for improving the precision of observational astronomy
%A Cramer, Claire E.
%A Brown, Steven W.
%A Lykke, Keith R.
%A Woodward, John T.
%A Bailey, Stephen
%A Schlegel, David J.
%A Bolton, Adam S.
%A Brownstein, Joel
%A Doherty, Peter E.
%A Stubbs, Christopher W.
%A Vaz, Amali
%A Szentgyorgyi, Andrew
%+ AA(National Institute of Standards and Technology (United States)), AB(National Institute of Standards and Technology (United States)), AC(National Institute of Standards and Technology (United States)), AD(National Institute of Standards and Technology (United States)), AE(Lawrence Berkeley National Lab. (United States)), AF(Lawrence Berkeley National Lab. (United States)), AG(The Univ. of Utah (United States)), AH(The Univ. of Utah (United States)), AI(Harvard Univ. (United States)), AJ(Harvard Univ. (United States)), AK(Harvard Univ. (United States)), AL(Harvard-Smithsonian Ctr. for Astrophysics (United States))
%J Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
%V 8450
%D 2012
%8 September 01, 2012
%P 84500S
%U https://ui.adsabs.harvard.edu/abs/2012SPIE.8450E..0SC
%X Improving the precision of observational astronomy requires not only new telescopes and instrumentation, but also advances in observing protocols, calibrations and data analysis. The Laser Applications Group at the National Institute of Standards and Technology in Gaithersburg, Maryland has been applying advances in detector metrology and tunable laser calibrations to problems in astronomy since 2007. Using similar measurement techniques, we have addressed a number of seemingly disparate issues: precision flux calibration for broad-band imaging, precision wavelength calibration for high-resolution spectroscopy, and precision PSF mapping for fiber spectrographs of any resolution. In each case, we rely on robust, commercially-available laboratory technology that is readily adapted to use at an observatory. In this paper, we give an overview of these techniques.
%R 10.1117/12.925198
%@ 0277-786X


%0 Journal Article
%T APOLLO: millimeter lunar laser ranging
%A Murphy, T. W., Jr.
%A Adelberger, E. G.
%A Battat, J. B. R.
%A Hoyle, C. D.
%A Johnson, N. H.
%A McMillan, R. J.
%A Stubbs, C. W.
%A Swanson, H. E.
%+ AA(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AB(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, USA), AC(Department of Physics, Bryn Mawr College, 101 N Merion Avenue, Bryn Mawr, PA 19010, USA), AD(Department of Physics and Astronomy, Humboldt State University, One Harpst St, Arcata, CA 95521-8299, USA), AE(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AF(Apache Point Observatory, 2001 Apache Point Rd, Sunspot, NM 88349-0059, USA), AG(Department of Physics, Harvard University, 17 Oxford St, Cambridge, MA 02318, USA), AH(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, USA)
%J Classical and Quantum Gravity
%V 29
%D 2012
%8 September 01, 2012
%P 184005
%U https://ui.adsabs.harvard.edu/abs/2012CQGra..29r4005M
%X Lunar laser ranging (LLR) has for decades stood at the forefront of tests of gravitational physics, including tests of the equivalence principle (EP). Current LLR results on the EP achieve a sensitivity of Δa/a ≈ 10<SUP>-13</SUP> based on few-centimeter data/model fidelity. A recent push in LLR, called APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) produces millimeter-quality data. This paper demonstrates the few-millimeter range precision achieved by APOLLO, leading to an expectation that LLR will be able to extend EP sensitivity by an order-of-magnitude to Δa/a ˜ 10<SUP>-14</SUP>, once modeling efforts improve to this level.
%R 10.1088/0264-9381/29/18/184005
%@ 0264-9381


%0 Conference Proceedings
%T Optical followup of galaxy clusters detected by the South Pole Telescope
%A Desai, S.
%A Armstrong, R.
%A Ashby, M. L. N.
%A Bayliss, B.
%A Bazin, G.
%A Benson, B.
%A Bertin, E.
%A Bleem, L.
%A Brodwin, M.
%A Clochiatti, A.
%A Foley, R.
%A Gladders, M.
%A Gonzalez, A. H.
%A High, F. W.
%A Liu, J.
%A Mohr, J.
%A Rest, A.
%A Ruel, J.
%A Saro, A.
%A Song, J.
%A Stalder, B.
%A Stanford, A.
%A Stubbs, C.
%A Zenteno, A.
%+ AA(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany ;), AB(Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA), AC(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AD(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AE(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany), AF(Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA), AG(Institut d'Astrophysique de Paris, 98 bis boulevard F-75014 Parago, Paris, France), AH(Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA), AI(Department of Physics, University of Missouri, 5100 Rockhill Road, Kansas City, MO 64110, USA), AJ(Department de Astronomia y Astrofisica, Ponticia Universidad Catolica de Chile, Casilla 306, Santiago 22, Chile), AK(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AL(Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA), AM(Department of Astronomy, University of Florida, Gainesville, FL 32611, USA), AN(Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA), AO(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany), AP(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany), AQ(Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA), AR(Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA), AS(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany), AT(Department of Physics, University of Michigan, 450 Church St. Ann Arbor, MI 48109, USA), AU(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AV(Department of Physics, University of California, 1 Shields Ave. Davis, CA 95616, USA), AW(Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA), AX(Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 München, Germany)
%J Journal of Physics Conference Series
%V 375
%D 2012
%8 July 01, 2012
%P 032011
%K Astrophysics - Cosmology and Extragalactic Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2012JPhCS.375c2011D
%X The South Pole Telescope (SPT) is a 10 meter telescope operating at mm wavelengths. It has recently completed a three-band survey covering 2500 sq. degrees. One of the survey's main goals is to detect galaxy clusters using Sunyaev-Zeldovich effect and use these clusters for a variety of cosmological and astrophysical studies such as the dark energy equation of state, the primordial non-gaussianity and the evolution of galaxy populations. Since 2005, we have been engaged in a comprehensive optical and near-infrared followup program (at wavelengths between 0.4 and 5 μm) to image high-significance SPT clusters, to measure their photometric redshifts, and to estimate the contamination rate of the candidate lists. These clusters are then used for various cosmological and astrophysical studies.
%R 10.1088/1742-6596/375/1/032011
%= eprint: arXiv:1201.5736
%@ 1742-6596


%0 Conference Paper
%T Ebullition-driven fluxes of methane from shallow hot spots suggest significant under-estimation of annual emission from the East Siberian Arctic Shelf
%A Shakhova, N. E.
%A Semiletov, I. P.
%A Salyuk, A.
%A Stubbs, C.
%A Kosmach, D.
%A Gustafsson, O.
%+ AA(IARC, Univerrsity Alaska Fairbanks, Fairbanks, AK, USA;), AB(IARC, Univerrsity Alaska Fairbanks, Fairbanks, AK, USA;), AC(Laboratory of Arctic Research, Pacific Oceanological Institute FEBRAS, Vladivostok, Russian Federation;), AD(University of California, Marine Science Institute, Santa Barbara, CA, USA;), AE(Laboratory of Arctic Research, Pacific Oceanological Institute FEBRAS, Vladivostok, Russian Federation;), AF(Institute of Applied Environmental Research, Stockholm University, Stockholm, Sweden;)
%J AGU Fall Meeting Abstracts
%V 2011
%D 2011
%8 December 01, 2011
%P GC41B-0794
%K 0312 ATMOSPHERIC COMPOSITION AND STRUCTURE / Air/sea constituent
fluxes; 0330 ATMOSPHERIC COMPOSITION AND STRUCTURE / Geochemical cycles;
0428 BIOGEOSCIENCES / Carbon cycling; 4219 OCEANOGRAPHY: GENERAL /
Continental shelf and slope processes
%U https://ui.adsabs.harvard.edu/abs/2011AGUFMGC41B0794S
%X The high-latitude, shallow ESAS has been alternately subaerial and inundated with seawater during glacial and interglacial periods respectively. Subaerial conditions foster the formation of permafrost and associated hydrate deposits whereas inundation with relatively warm seawater destabilizes the permafrost and hydrates. Our measurements of CH4 in 1994-2000 and 2003-2010 over ESAS demonstrate the system to be in a destabilization period. First estimates of ESAS methane emissions indicated the current atmospheric budget, which arises from gradual diffusion and ebullition, was on par with estimates of methane emissions from the entire World Ocean (≈8 Tg-CH4). Large transient emissions remained to be assessed; yet initial data suggested that component could increase significantly annual emissions. New data obtained in 2008-2010 show that contribution of ebullition-driven CH4 fluxes from shallow hot spots alone could multiply previously reported annual emission from the entire ESAS.


%0 Conference Paper
%T Spatial distribution of methane seepage on the East Siberian Arctic Shelf
%A Stubbs, C.
%A Leifer, I.
%A Shakhova, N. E.
%A Semiletov, I. P.
%A Luyendyk, B. P.
%+ AA(Department of Earth Science, University of California, Santa Barbara, CA, USA), AB(Marine Science Institute, University of California, Santa Barbara, CA, USA), AC(International Arctic Research Center, University of Alaska, Fairbanks, AK, USA), AD(International Arctic Research Center, University of Alaska, Fairbanks, AK, USA), AE(Department of Earth Science, University of California, Santa Barbara, CA, USA)
%J AGU Fall Meeting Abstracts
%V 2010
%D 2010
%8 December 01, 2010
%P GC43D-0998
%K 0428 BIOGEOSCIENCES / Carbon cycling; 0429 BIOGEOSCIENCES / Climate
dynamics; 1050 GEOCHEMISTRY / Marine geochemistry; 4273 OCEANOGRAPHY:
GENERAL / Physical and biogeochemical interactions
%U https://ui.adsabs.harvard.edu/abs/2010AGUFMGC43D0998S
%X A 2009 multibeam sonar survey of the shallow water-column (mean depth 10 m), near-coastal region of the East Siberian Arctic Shelf (ESAS) adjacent to the Lena River Delta detected tens of thousands of widespread bubble plume seeps. The ESAS contains an estimated 1400 GT (109 tons = 1 GT) of carbon sequestered within and beneath a sub-sea permafrost unit that has become inundated due to sea-level transgression over the last ~15,000 years. This carbon pool includes methane (CH4) as free and dissolved gas, as well as potentially extensive methane hydrate deposits, yet its contribution to global carbon stocks has traditionally been ignored due to the assumed integrity of the sub-sea permafrost as an impermeable barrier to hydrocarbon migration. Recent results indicate that in some regions of the ESAS, methane is migrating through destabilized permafrost into the shallow water-column from which it efficiently vents to the atmosphere. This process represents an unknown but potentially significant contribution to the global greenhouse gas budget and is likely to accelerate under global warming scenarios. We hypothesize that the mapped seeps are fed by methane deposits within and beneath capping permafrost units that release gas into the thin overlying sediments through columns of thaw sediments and other permeable structures within the permafrost. Such sub-sea permafrost features have been previously identified in association with isolated bubble plumes in the ESAS as close as 25 km from the study area (Rekant et al., 2009). These proposed migration pathways suggest thermal destabilization within the subsea permafrost cap; however, the rates at which these processes are occurring remain unknown. The spatial distributions of the most numerous and intense areas of seepage correlate with the areas of greatest fluvial discharge from the Lena and Olenek Rivers and their tributaries. This thermal influence is also evident in seasonal time series of adjacent sea ice retreat over the same areas of intense seepage. These associations suggests that warm terrestrial runoff from coastal Siberian rivers is providing significant heat to areas of sub-sea permafrost and affecting the thermal regime controlling the stability of the sequestered carbon pool.


%0 Conference Proceedings
%T Ground-based observatory operations optimized and enhanced by direct atmospheric measurements
%A McGraw, John T.
%A Zimmer, Peter C.
%A Ackermann, Mark R.
%A Hines, Dean C.
%A Hull, Anthony B.
%A Rossmann, Lisa
%A Zirzow, Daniel C.
%A Brown, Steven W.
%A Fraser, Gerald T.
%A Lykke, Keith R.
%A Smith, Allan W.
%A Stubbs, Christopher W.
%A Woodward, John T.
%+ AA(The Univ. of New Mexico, United States), AB(The Univ. of New Mexico, United States), AC(The Univ. of New Mexico, United States), AD(The Univ. of New Mexico, United States), AE(The Univ. of New Mexico, United States), AF(The Univ. of New Mexico, United States), AG(The Univ. of New Mexico, United States), AH(National Institute of Standards and Technology, United States), AI(National Institute of Standards and Technology, United States), AJ(National Institute of Standards and Technology, United States), AK(National Institute of Standards and Technology, United States), AL(Harvard Univ., United States), AM(National Institute of Standards and Technology, United States)
%J Modern Technologies in Space- and Ground-based Telescopes and Instrumentation
%V 7739
%D 2010
%8 July 01, 2010
%P 773929
%U https://ui.adsabs.harvard.edu/abs/2010SPIE.7739E..29M
%X Earth's atmosphere represents a turbulent, turbid refractive element for every ground-based telescope. We describe the significantly enhanced and optimized operation of observatories supported by the combination of a lidar and spectrophotometer that allows accurate, provable measurement of and correction for direction-, wavelength- and timedependent astronomical extinction. The data provided by this instrument suite enables atmospheric extinction correction leading to "sub-1%" imaging photometric precision, and attaining the fundamental photon noise limit. In addition, this facility-class instrument suite provides quantitative atmospheric data over the dome of the sky that allows robust realtime decision-making about the photometric quality of a night, enabling more efficient queue-based, service, and observer-determined telescope utilization. With operational certainty, marginal photometric time can be redirected to other programs, allowing useful data to be acquired. Significantly enhanced utility and efficiency in the operation of telescopes result in improved benefit-to-cost for ground-based observatories. We propose that this level of decision-making will make large-area imaging photometric surveys, such as Pan-STARRS and the future LSST both more effective in terms of photometry and in the use of telescopes generally. The atmospheric data will indicate when angular or temporal changes in atmospheric transmission could have significant effect across the rather wide fields-of-view of these telescopes. We further propose that implementation of this type of instrument suite for direct measurement of Earth's atmosphere will enable observing programs complementary to those currently requiring space-based observations to achieve the required measurement precision, such as ground-based versions of the Kepler Survey or the Joint Dark Energy Mission.
%R 10.1117/12.857787
%@ 0277-786X


%0 Conference Proceedings
%T Calibration dome screen for the Large Synoptic Survey Telescope
%A Gressler, William J.
%A Doherty, Peter
%A Krabbendam, Victor L.
%A Liang, Ming
%A Saha, Abhijit
%A Stubbs, Christopher W.
%A Vaz, Amali
%+ AA(National Optical Astronomy Observatory, United States), AB(Harvard Univ., United States), AC(National Optical Astronomy Observatory, United States), AD(National Optical Astronomy Observatory, United States), AE(National Optical Astronomy Observatory, United States), AF(Harvard Univ., United States), AG(Harvard Univ., United States)
%J Modern Technologies in Space- and Ground-based Telescopes and Instrumentation
%V 7739
%D 2010
%8 July 01, 2010
%P 77391P
%U https://ui.adsabs.harvard.edu/abs/2010SPIE.7739E..1PG
%X The Large Synoptic Survey Telescope (LSST) flat-fields must repeatedly trace not only the spatial response variations, but also the chromatic response through the entire optical system, with an accuracy driven by the photometric requirements for the LSST survey data. This places challenging requirements on the LSST Calibration Dome Screen, which must uniformly illuminate the 8.4-meter diameter telescope pupil over its 3.5-degree field of view at desired monochromatic wavelengths in a way that allows the measurement of the total system throughput from entrance pupil to the digitization of charge in the camera electronics. This includes the reflectivity of the mirrors, transmission of the refractive optics and filters, the quantum efficiency of the sensors in the camera, and the gain and linearity of the sensor read-out electronics. The baseline design uses a single tunable laser and includes an array of discrete projectors. The projected flux of light produced by the screen must fill the entire telescope pupil and provide uniform illumination to 1% at the focal plane and to within 0.25% over any optical trajectory within 0.5 degrees of each other. The wavelength of light is tunable across the LSST bandpass from 320 nm to 1080 nm. The screen also includes a broad-band ("white") light source with known Spectral Energy Density (SED) that spans the same range of wavelengths.
%R 10.1117/12.857425
%@ 0277-786X


%0 Conference Proceedings
%T Spectroradiometric calibration of telescopes using laser illumination of flat field screens
%A Woodward, John T.
%A Brown, Steven W.
%A Lykke, Keith R.
%A Smith, Allan W.
%A Cramer, Claire E.
%A Doherty, Peter E.
%A Falco, Emilio
%A Stubbs, Christopher
%+ AA(National Institute of Standards and Technology, United States), AB(National Institute of Standards and Technology, United States), AC(National Institute of Standards and Technology, United States), AD(National Institute of Standards and Technology, United States), AE(National Institute of Standards and Technology, United States), AF(Harvard-Smithsonian Ctr. for Astrophysics, United States), AG(Harvard-Smithsonian Ctr. for Astrophysics, United States), AH(Harvard-Smithsonian Ctr. for Astrophysics, United States)
%J Observatory Operations: Strategies, Processes, and Systems III
%V 7737
%D 2010
%8 July 01, 2010
%P 77372A
%U https://ui.adsabs.harvard.edu/abs/2010SPIE.7737E..2AW
%X It is standard practice at many telescopes to take a series of flat field images prior to an observation run. Typically the flat field consists of a screen mounted inside the telescope dome that is uniformly illuminated with a broadband light source. These flat field images are useful for characterizing the relative response of CCD pixels to light passing through the telescope optics and filters, but carry limited spectral information and are not calibrated for absolute flux. We present the results of performing in situ, spectroradiometric calibrations of a 1.2 m telescope at the Fred Lawrence Whipple Observatory, Mt. Hopkins, AZ. To perform a spectroradiometric calibration, a laser, tunable through the visible to near infrared, was coupled into an optical fiber and used to illuminate the flat field screen in situ at the telescope facility. A NIST traceable, calibrated photodiode was mounted on the telescope to measure the spectral flux reaching the aperture. For a particular filter, images of the screen were then captured for each laser wavelength as the wavelength was tuned over the filter bandpass. Knowledge of the incident flux then allows the relative responsivity of each CCD pixel at each wavelength to be calculated.
%R 10.1117/12.857474
%@ 0277-786X


%0 Conference Proceedings
%T Calibration of the LSST instrumental and atmospheric photometric passbands
%A Burke, David L.
%A Axelrod, T.
%A Barrau, Aurélien
%A Baumont, Sylvain
%A Blondin, Stéphane
%A Claver, Charles
%A Gorecki, Alexia
%A Ivezic, Zeljko
%A Jones, Lynne
%A Krabbendam, Victor
%A Liang, Ming
%A Saha, Abhijit
%A Smith, Allyn
%A Smith, R. Christopher
%A Stubbs, Christopher W.
%A Vescovi, Christophe
%A Team, LSST Project
%+ AA(SLAC National Accelerator Lab., United States), AB(Steward Observatory, Univ. of Arizona, United States), AC(Lab. de Physique Subatomique et de Cosmologie de Grenoble, CNRS-IN2P3, France), AD(Lab. de Physique Subatomique et de Cosmologie de Grenoble, CNRS-IN2P3, France), AE(Ctr. de Physique des Particules de Marseille, CNRS-IN2P3, France), AF(National Optical Astronomy Observatory, United States), AG(Lab. de Physique Subatomique et de Cosmologie de Grenoble, CNRS-IN2P3, France), AH(Univ. of Washington, United States), AI(Univ. of Washington, United States), AJ(National Optical Astronomy Observatory, United States), AK(National Optical Astronomy Observatory, United States), AL(National Optical Astronomy Observatory, United States), AM(Austin Peay State Univ., United States), AN(Cerro Tololo Inter-American Observatory, United States), AO(Harvard-Smithsonian Ctr. for Astrophysics, Harvard Univ., United States), AP(Lab. de Physique Subatomique et de Cosmologie de Grenoble, CNRS-IN2P3, France), AQ(LSST Corp., United States)
%J Observatory Operations: Strategies, Processes, and Systems III
%V 7737
%D 2010
%8 July 01, 2010
%P 77371D
%U https://ui.adsabs.harvard.edu/abs/2010SPIE.7737E..1DB
%X The Large Synoptic Survey Telescope (LSST) will continuously image the entire sky visible from Cerro Pachon in northern Chile every 3-4 nights throughout the year. The LSST will provide data for a broad range of science investigations that require better than 1% photometric precision across the sky (repeatability and uniformity) and a similar accuracy of measured broadband color. The fast and persistent cadence of the LSST survey will significantly improve the temporal sampling rate with which celestial events and motions are tracked. To achieve these goals, and to optimally utilize the observing calendar, it will be necessary to obtain excellent photometric calibration of data taken over a wide range of observing conditions - even those not normally considered "photometric". To achieve this it will be necessary to routinely and accurately measure the full optical passband that includes the atmosphere as well as the instrumental telescope and camera system. The LSST mountain facility will include a new monochromatic dome illumination projector system to measure the detailed wavelength dependence of the instrumental passband for each channel in the system. The facility will also include an auxiliary spectroscopic telescope dedicated to measurement of atmospheric transparency at all locations in the sky during LSST observing. In this paper, we describe these systems and present laboratory and observational data that illustrate their performance.
%R 10.1117/12.857236
%@ 0277-786X


%0 Conference Proceedings
%T Space-based photometric precision from ground-based telescopes
%A Zimmer, Peter C.
%A Mcgraw, John T.
%A Ackermann, Mark R.
%A Hines, Dean C.
%A Hull, Anthony B.
%A Rossmann, Lisa
%A Zirzow, Daniel C.
%A Brown, Steven W.
%A Cramer, Claire E.
%A Fraser, Gerald T.
%A Lykke, Keith R.
%A Smith, Allan W.
%A Stubbs, Christopher W.
%A Woodward, John T.
%+ AA(The Univ. of New Mexico, United States), AB(The Univ. of New Mexico, United States), AC(The Univ. of New Mexico, United States), AD(The Univ. of New Mexico, United States), AE(The Univ. of New Mexico, United States), AF(The Univ. of New Mexico, United States), AG(The Univ. of New Mexico, United States), AH(National Institute of Standards and Technology, United States), AI(National Institute of Standards and Technology, United States), AJ(National Institute of Standards and Technology, United States), AK(National Institute of Standards and Technology, United States), AL(National Institute of Standards and Technology, United States), AM(Harvard Univ., United States), AN(National Institute of Standards and Technology, United States)
%J Ground-based and Airborne Instrumentation for Astronomy III
%V 7735
%D 2010
%8 July 01, 2010
%P 77358D
%U https://ui.adsabs.harvard.edu/abs/2010SPIE.7735E..8DZ
%X Ground-based telescopes supported by lidar and spectrophotometric auxiliary instrumentation can attain space-based precision for all-sky photometry, with uncertainties dominated by fundamental photon counting statistics. Earth's atmosphere is a wavelength-, directionally- and time-dependent turbid refractive element for every ground-based telescope, and is the primary factor limiting photometric measurement precision. To correct accurately for the transmission of the atmosphere requires direct measurements of the wavelength-dependent transmission in the direction and at the time that the supported photometric telescope is acquiring its data. While considerable resources have been devoted to correcting the effects of the atmosphere on angular resolution, the effects on precision photometry have largely been ignored. We describe the facility-class lidar that observes the stable stratosphere, and a spectrophotometer that observes NIST absolutely calibrated standard stars, the combination of which enables fundamentally statistically limited photometric precision. This inexpensive and replicable instrument suite provides the lidar-determined monochromatic absolute transmission of Earth's atmosphere at visible and near-infrared wavelengths to 0.25% per airmass and the wavelengthdependent transparency to less than 1% uncertainty per minute. The atmospheric data are merged to create a metadata stream that allows throughput corrections from data acquired at the time of the scientific observations to be applied to broadband and spectrophotometric scientific data. This new technique replaces the classical use of nightly mean atmospheric extinction coefficients, which invoke a stationary and plane-parallel atmosphere. We demonstrate application of this instrument suite to stellar photometry, and discuss the enhanced value of routinely provably precise photometry obtained with existing and future ground-based telescopes.
%R 10.1117/12.857700
%@ 0277-786X


%0 Conference Paper
%T Multibeam sonar mapping of Siberian seeps: Evaluating trends in methane flux from shallow sub-sea permafrost
%A Stubbs, Christopher
%A Leifer, Ira
%A Luyendyk, Bruce
%A Semiletov, Igor
%+ AA(Department of Earth Science, University of California, Santa Barbara, USA ; Department of Earth Science, University of California, Santa Barbara, USA), AB(Department of Earth Science, University of California, Santa Barbara, USA), AC(Department of Earth Science, University of California, Santa Barbara, USA), AD(International Arctic Research Center, University of Alaska, Fairbanks, USA ; Russian Academy of Sciences, Far Eastern Division)
%J EGU General Assembly Conference Abstracts
%D 2010
%8 May 01, 2010
%P 1046
%U https://ui.adsabs.harvard.edu/abs/2010EGUGA..12.1046S
%X The East Siberian Arctic Shelf (ESAS) contains an estimated 1400 GT (109 tons = 1 GT) of carbon sequestered within and beneath a sub-sea permafrost unit that is overlain by thin sediments. This carbon pool includes methane (CH4) as free and dissolved gas, potentially extensive methane hydrate deposits, and carbon dioxide (CO2), yet its contribution has traditionally been ignored in global carbon stocks because of its assumed stability. The ESAS is very shallow averaging &lt; 50 m depth over its 2x10<SUP>6</SUP> km2 area, 80% of which is predicted to contain originally sub-areal permafrost unit, now submerged due to transgression. Associated with transgression was a new thermal regime including enhanced heat transfer from warming Arctic Oceans and terrestrial riverine waters to the submerged permafrost, as well as from exothermic oxidation reactions and geothermal sources. As a result, large areas of integrity loss have been identified from widespread bubble ebullition and enhanced aqueous methane levels well above atmospheric equilibrium. The resulting thaw sediments (taliks) and structural breaches facilitate fluid and gas migration within the permafrost to overlying sediments where some microbial methane oxidation occurs. These destabilizing features may also provide a mechanism for enhanced heat transfer to methane hydrate deposits. The shallow nature of the ESAS means ascending bubbles in the water column experience minimal dissolution before venting to the atmosphere. Additionally, storm mixing extends to the seabed so that virtually all dissolved methane gas from bubbles and sediment fluid exchange is stripped from the oceanic waters and vented to the atmosphere prior to the microbial oxidation. Emission of CH4 and CO2 largely remain unquantified but potentially contribute significantly to atmospheric budgets. Further, rapid Arctic warming suggests these gas emissions could present a significant positive warming feedback. Given the rapid climate changes occurring and predicted to occur in the Arctic, there is a strong need for baseline measurements of ebullition to allow identification of emission trends. Baseline data were collected in Fall 2009 using multibeam sonar surveying techniques developed at UCSB. Data analysis has identified spatial and temporal controls on seepage bubble flux including geologic structure, and currents. Two sonar techniques were used in the ESAS. The first method used a pole-mounted 260 kHz 120° X 3° Imagenex Delta-T, which recorded two weeks of data continuously while steaming. The transducer swath was pitched forward of vertical to better discriminate vertical plume structures and the complete water-column returns were logged. A seabed-tracking depth window from each ping was summed vertically to account for the discontinuous nature of bubble plumes and lessen the representation of non-bubble sonar returns. Data were geo-rectified and mapped. Numerous bubble streams in shallow (6-20 m) water were identified using sonar in areas predicted to be underlain by permafrost. The second method used a vessel-tethered stationary frame on the seabed with the Delta-T sonar rotating continuously through 330° around a vertical axis with the swath arrayed vertically and the beams spanning from below the seabed to above the sea surface. This 4D method is a major improvement over multibeam sonar measurement in a horizontal plane, allowing for automated segregation between fish and seeps, improved gas flux calibration, current profile estimation, and measurement of wave characteristics, wave-driven bubble plumes, and bathymetric repeat mapping of the seabed.


%0 Journal Article
%T The Use of Time-Resolved Fluorescence Anisotropy to Reveal Domain Structures in Model Membrane Vesicles: Prospects for Applications to Cell Membranes
%A Stubbs, Christopher D.
%A Botchway, Stanley B.
%J Biophysical Journal
%V 98
%D 2010
%8 January 01, 2010
%P 663a
%U https://ui.adsabs.harvard.edu/abs/2010BpJ....98R.663S
%R 10.1016/j.bpj.2009.12.4249
%@ 0006-3495


%0 Conference Paper
%T Does Your Hydraulic Containment System Really Capture Everything?
%A Chu, M. J.
%A Stubbs, C. M.
%+ AA(ENVIRON International Corp., Emeryville, CA, United States), AB(ENVIRON International Corp., Emeryville, CA, United States)
%J AGU Fall Meeting Abstracts
%V 2009
%D 2009
%8 December 01, 2009
%P H51N-05
%K 1828 HYDROLOGY / Groundwater hydraulics; 1832 HYDROLOGY / Groundwater
transport; 1846 HYDROLOGY / Model calibration; 1848 HYDROLOGY /
Monitoring networks
%U https://ui.adsabs.harvard.edu/abs/2009AGUFM.H51N..05C
%X Hydraulic containment remains one of the most practical options for controlling the spread of large contaminant plumes at great depth (&gt;300 feet below ground surface). Currently, hydraulic containment systems for plumes located in deep and complex hydrogeological settings are designed primarily through numerical groundwater modeling. The ultimate goal of such modeling is often to estimate the groundwater extraction rates required to achieve complete plume capture. Because of time and resources constraints, many modeling practitioners use the following conventional approach to tackle the problem: calibrate the groundwater flow model of interest, then vary the calibrated hydraulic conductivity field over a reasonable range to obtain a range of extraction rates that may be needed for plume capture. Although it is easy to implement, this conventional approach may be inadequate for two primary reasons. First, varying the hydraulic conductivity field alone often makes the model deviate from the calibrated conditions; therefore, extraction rates estimated under such conditions may be misleading. Second, the effects of parameter nonuniqueness are frequently not explored through the conventional modeling approach, potentially resulting in significant additional uncertainty in the estimated extraction rates. While the accuracy of modeled extraction rates do not solely dictate the final success of a hydraulic containment system, a better understanding of the extent of uncertainty can definitely improve decision making for large-scale projects. A classic example of parameter nonuniqueness that has been repeatedly encountered in real world applications is the difficulty in decoupling the effects of recharge and hydraulic conductivity on groundwater head observations. To provide some perspective on this topic from an industry and consulting standpoint, we will present a “hypothetical” case study based on numerous challenging site investigation projects we have worked on. This case includes the following key components: a large contaminant plume in a multi-layered aquifer, a barrier fault that influences plume migration, nearby production well activity, and spatially-varying recharge. We will illustrate the major sources of uncertainty impacting a groundwater flow model, the challenges of collecting useful data to improve model calibration, how parameter uncertainty is translated into uncertainty in estimated extraction rates for a hypothetical hydraulic containment system, and how to communicate issues of uncertainty with decision makers.


%0 Journal Article
%T Equivalence principle implications of modified gravity models
%A Hui, Lam
%A Nicolis, Alberto
%A Stubbs, Christopher W.
%+ AA(Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Department of Physics, Columbia University, New York, New York 10027, USA), AB(Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Department of Physics, Columbia University, New York, New York 10027, USA), AC(Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA)
%J Physical Review D
%V 80
%D 2009
%8 November 01, 2009
%P 104002
%K 04.50.-h; 04.80.Cc; 95.35.+d; 98.80.Cq; Higher-dimensional gravity
and other theories of gravity; Experimental tests of gravitational
theories; Dark matter; Particle-theory and field-theory models of the
early Universe; Astrophysics - Cosmology and Extragalactic Astrophysics;
Astrophysics - Galaxy Astrophysics; Astrophysics - High Energy
Astrophysical Phenomena; General Relativity and Quantum Cosmology; High
Energy Physics - Theory
%U https://ui.adsabs.harvard.edu/abs/2009PhRvD..80j4002H
%X Theories that attempt to explain the observed cosmic acceleration by modifying general relativity all introduce a new scalar degree of freedom that is active on large scales, but is screened on small scales to match experiments. We demonstrate that if such screening occurs via the chameleon mechanism, such as in f(R) theory, it is possible to have order unity violation of the equivalence principle, despite the absence of explicit violation in the microscopic action. Namely, extended objects such as galaxies or constituents thereof do not all fall at the same rate. The chameleon mechanism can screen the scalar charge for large objects but not for small ones (large/small is defined by the depth of the gravitational potential and is controlled by the scalar coupling). This leads to order one fluctuations in the ratio of the inertial mass to gravitational mass. We provide derivations in both Einstein and Jordan frames. In Jordan frame, it is no longer true that all objects move on geodesics; only unscreened ones, such as test particles, do. In contrast, if the scalar screening occurs via strong coupling, such as in the Dvali-Gabadadze-Porrati braneworld model, equivalence principle violation occurs at a much reduced level. We propose several observational tests of the chameleon mechanism: 1. small galaxies should accelerate faster than large galaxies, even in environments where dynamical friction is negligible; 2. voids defined by small galaxies would appear larger compared to standard expectations; 3. stars and diffuse gas in small galaxies should have different velocities, even if they are on the same orbits; 4. lensing and dynamical mass estimates should agree for large galaxies but disagree for small ones. We discuss possible pitfalls in some of these tests. The cleanest is the third one where the mass estimate from HI rotational velocity could exceed that from stars by 30% or more. To avoid blanket screening of all objects, the most promising place to look is in voids.
%R 10.1103/PhysRevD.80.104002
%= eprint: arXiv:0905.2966
%@ 1550-79980556-2821


%0 Conference Proceedings
%T A proposed global atmospheric monitoring network based on standard stars
%A McGraw, John T.
%A Zimmer, Peter C.
%A Brown, Steven W.
%A Fraser, Gerald T.
%A Lykke, Keith R.
%A Smith, Allan W.
%A Stubbs, Christopher W.
%A Woodward, John T.
%+ AA(The University of New Mexico (USA)), AB(The University of New Mexico (USA)), AC(National Institute of Standards and Technology (USA)), AD(National Institute of Standards and Technology (USA)), AE(National Institute of Standards and Technology (USA)), AF(National Institute of Standards and Technology (USA)), AG(Harvard Univ. (USA)), AH(National Institute of Standards and Technology (USA))
%J Infrared Spaceborne Remote Sensing and Instrumentation XVII
%V 7453
%D 2009
%8 August 01, 2009
%P 74530K
%U https://ui.adsabs.harvard.edu/abs/2009SPIE.7453E..0KM
%X The feasibility of developing a network of telescopes to monitor the composition of the nighttime atmosphere using stellar spectrophotometry is explored. Spectral measurements of the extinction of starlight by the atmosphere would allow, for instance, quantification of aerosol, cloud, water-vapor, and ozone levels over the full range of elevation and azimuth. These measurements, when combined with data from solar spectrophotometry derived from other instruments, would provide continuous day/night monitoring of the atmospheric composition from the ground. The foundation for such an effort would be a set of stable standard stars with known top-of-the-atmosphere spectral irradiances traceable to international standards based on the SI system of units. Fully automated, reliable, easily maintained and highly costeffective replicas of the spectrophotometric telescope used to calibrate the standard stars can be deployed worldwide at sites such as atmospheric and astronomical observatories.
%R 10.1117/12.831213
%@ 0277-786X


%0 Journal Article
%T Dark-Matter-Induced Violation of the Weak Equivalence Principle
%A Carroll, Sean M.
%A Mantry, Sonny
%A Ramsey-Musolf, Michael J.
%A Stubbs, Christoper W.
%+ AA(California Institute of Technology, Pasadena, California 91125, USA), AB(California Institute of Technology, Pasadena, California 91125, USA), AC(University of Wisconsin-Madison, Madison, Wisconsin 53706, USA; California Institute of Technology, Pasadena, California 91125, USA), AD(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA)
%J Physical Review Letters
%V 103
%D 2009
%8 July 01, 2009
%P 011301
%K 95.35.+d; 04.80.Cc; 14.80.-j; Dark matter; Experimental tests of
gravitational theories; Other particles; High Energy Physics -
Phenomenology; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2009PhRvL.103a1301C
%X A long-range fifth force coupled to dark matter can induce a coupling to ordinary matter if the dark matter interacts with standard model fields. We consider constraints on such a scenario from both astrophysical observations and laboratory experiments. We also examine the case where the dark matter is a weakly interacting massive particle, and derive relations between the coupling to dark matter and the coupling to ordinary matter for different models. Currently, this scenario is most tightly constrained by galactic dynamics, but improvements in Eötvös experiments can probe unconstrained regions of parameter space.
%R 10.1103/PhysRevLett.103.011301
%= eprint: arXiv:0807.4363
%@ 0031-9007


%0 Conference Proceedings
%T Parametrization and Classification of 20 Billion LSST Objects: Lessons from SDSS
%A Ivezić, Ž.
%A Axelrod, T.
%A Becker, A. C.
%A Becla, J.
%A Borne, K.
%A Burke, D. L.
%A Claver, C. F.
%A Cook, K. H.
%A Connolly, A.
%A Gilmore, D. K.
%A Jones, R. L.
%A Jurić, M.
%A Kahn, S. M.
%A Lim, K. -T.
%A Lupton, R. H.
%A Monet, D. G.
%A Pinto, P. A.
%A Sesar, B.
%A Stubbs, C. W.
%A Tyson, J. A.
%+ AA(University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195), AB(LSST Corporation, 933 N. Cherry Avenue, Tucson, AZ 85721), AC(University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195), AD(Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309), AE(Department of Comput. and Data Sciences, George Mason University, MS 6A2, Fairfax, VA, 22030, USA), AF(Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309), AG(National Optical Astronomy Observatory, 950 N. Cherry Ave, Tucson, AZ 85719), AH(Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550), AI(University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195), AJ(Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309), AK(University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195), AL(Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540), AM(Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309), AN(Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309), AO(Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544), AP(U.S. Naval Observatory Flagstaff Station, 10391 Naval Observatory Road, Flagstaff, AZ 86001), AQ(Steward Observatory, The University of Arizona, 933 N Cherry Ave., Tucson, AZ 85721), AR(University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195), AS(Center for Astrophysics, Harvard University, 60 Garden St., Cambridge, MA 02138), AT(Physics Department, University of California, One Shields Avenue, Davis, CA 95616)
%J Classification and Discovery in Large Astronomical Surveys
%V 1082
%D 2008
%8 December 01, 2008
%P 359
%K 95.55.Fw; 98.54.-h; 96.30.Ys; Space-based ultraviolet optical and
infrared telescopes; Quasars; active or peculiar galaxies objects and
systems; Asteroids meteoroids; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2008AIPC.1082..359I
%X The Large Synoptic Survey Telescope (LSST) will be a large, wide-field ground-based system designed to obtain, starting in 2015, multiple images of the sky that is visible from Cerro Pachon in Northern Chile. About 90% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 deg<SUP>2</SUP> region about 1000 times during the anticipated 10 years of operations (distributed over six bands, ugrizy). Each 30-second long visit will deliver 5σ depth for point sources of r~24.5 on average. The co-added map will be about 3 magnitudes deeper, and will include 10 billion galaxies and a similar number of stars. We discuss various measurements that will be automatically performed for these 20 billion sources, and how they can be used for classification and determination of source physical and other properties. We provide a few classification examples based on SDSS data, such as color classification of stars, color-spatial proximity search for wide-angle binary stars, orbital-color classification of asteroid families, and the recognition of main Galaxy components based on the distribution of stars in the position-metallicity-kinematics space. Guided by these examples, we anticipate that two grand classification challenges for LSST will be 1) rapid and robust classification of sources detected in difference images, and 2) simultaneous treatment of diverse astrometric and photometric time series measurements for an unprecedentedly large number of objects.
%R 10.1063/1.3059076
%= eprint: arXiv:0810.5155
%@ 0094-243X


%0 Journal Article
%T Linking optical and infrared observations with gravitational wave sources through transient variability
%A Stubbs, C. W.
%+ AA(Department of Physics, Department of Astronomy, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA)
%J Classical and Quantum Gravity
%V 25
%D 2008
%8 September 01, 2008
%P 184033
%K Astrophysics; General Relativity and Quantum Cosmology
%U https://ui.adsabs.harvard.edu/abs/2008CQGra..25r4033S
%X Optical and infrared observations have thus far detected more celestial cataclysms than have been seen in gravity waves (GW). This argues that we should search for gravity wave signatures that correspond to transient variables seen at optical wavelengths, at precisely known positions. There is an unknown time delay between the optical and gravitational transient, but knowing the source location precisely specifies the corresponding time delays across the gravitational antenna network as a function of the GW-to-optical arrival time difference. Optical searches should detect virtually all supernovae that are plausible gravitational radiation sources. The transient optical signature expected from merging compact objects is not as well understood, but there are good reasons to expect detectable transient optical/IR emission from most of these sources as well. The next generation of deep wide-field surveys (for example PanSTARRS and LSST) will be sensitive to subtle optical variability, but we need to fill the 'blind spots' that exist in the galactic plane, and for optically bright transient sources. In particular, a galactic plane variability survey at λ~ 2 µm seems worthwhile. Science would benefit from closer coordination between the various optical survey projects and the gravity wave community.
%R 10.1088/0264-9381/25/18/184033
%= eprint: arXiv:0712.2598
%@ 0264-9381


%0 Journal Article
%T Solar system constraints on the Dvali-Gabadadze-Porrati braneworld theory of gravity
%A Battat, James B. R.
%A Stubbs, Christopher W.
%A Chandler, John F.
%+ AA(Department of Astronomy, Center for Astrophysics, Harvard University, Cambridge, Massachusetts 02138, USA), AB(Department of Astronomy, Center for Astrophysics, Harvard University, Cambridge, Massachusetts 02138, USA), AC(Center for Astrophysics, Harvard University, Cambridge, Massachusetts 02138, USA)
%J Physical Review D
%V 78
%D 2008
%8 July 01, 2008
%P 022003
%K 04.80.-y; 04.50.-h; 04.50.Kd; 96.30.-t; Experimental studies of
gravity; Higher-dimensional gravity and other theories of gravity;
Modified theories of gravity; Solar system objects; General Relativity
and Quantum Cosmology; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2008PhRvD..78b2003B
%X A number of proposals have been put forward to account for the observed accelerating expansion of the Universe through modifications of gravity. One specific scenario, Dvali-Gabadadze-Porrati (DGP) gravity, gives rise to a potentially observable anomaly in the solar system: all planets would exhibit a common anomalous precession, dω/dt, in excess of the prediction of general relativity. We have used the Planetary Ephemeris Program (PEP) along with planetary radar and radio tracking data to set a constraint of |dω/dt|<SUB>obs</SUB>&lt;0.02 arcseconds per century on the presence of any such common precession. This sensitivity falls short of that needed to detect the estimated universal precession of |dω/dt|<SUB>DGP</SUB>=5×10<SUP>-4</SUP> arcseconds per century expected in the DGP scenario. We discuss the fact that ranging data between objects that orbit in a common plane cannot constrain the DGP scenario. It is only through the relative inclinations of the planetary orbital planes that solar system ranging data have sensitivity to the DGP-like effect of universal precession. In addition, we illustrate the importance of performing a numerical evaluation of the sensitivity of the data set and model to any perturbative precession.
%R 10.1103/PhysRevD.78.022003
%= eprint: arXiv:0805.4466
%@ 1550-79980556-2821


%0 Conference Paper
%T Constraints on Lorentz Violation with Precision Measurements of the Lunar Orbit
%A Battat, James
%A Chandler, John
%A Stubbs, Christopher
%J APS April Meeting Abstracts
%D 2008
%8 April 01, 2008
%P T10.003
%U https://ui.adsabs.harvard.edu/abs/2008APS..APRT10003B
%X Efforts to unify the fundamental forces of nature have produced theories that violate Lorentz symmetry. The Standard Model Extension (SME) has emerged as a comprehensive theoretical framework which parametrizes Lorentz violations. The SME was recently extended to include gravitational interactions, and it was shown that existing Lunar Laser Ranging (LLR) data is sensitive to violations of Lorentz symmetry. LLR measures the Earth-Moon separation by timing the round trip travel of pulsed laser light from a telescope on the Earth to corner cube retroreflectors on the lunar surface. LLR has provided precision measurements of the Earth-Moon separation for nearly 40 years. We present a new analysis of 35 years of archival, LLR data. Our work places the first constraints on six independent linear combinations of SME parameters and we find no evidence for Lorentz symmetry violation at the part in 10<SUP>-6</SUP> to 10<SUP>-11</SUP> level in these parameters. Forthcoming millimeter-precision LLR data from the Apache Point Observatory Lunar Laser-ranging Operation (see talk on APOLLO by Thomas Murphy) will further improve these constraints.


%0 Conference Proceedings
%T The First Lunar Laser Ranging Constraints on Gravity Sector SME Parameters
%A Battat, J. B. R.
%A Chandler, J. F.
%A Stubbs, C. W.
%+ AA(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AB(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA), AC(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA)
%J CPT and Lorentz Symmetry
%D 2008
%8 March 01, 2008
%P 265
%K General Relativity and Quantum Cosmology; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2008cls..conf..265B
%X We present the first constraints on pure-gravity sector Standard-Model Extension (SME) parameters using Lunar Laser Ranging (LLR). LLR measures the round trip travel time of light between the Earth and the Moon. With 34+ years of LLR data, we have constrained six independent linear combinations of SME parameters at the level of 10<SUP>-6</SUP> to 10<SUP>-11</SUP>. There is no evidence for Lorentz violation in the LLR dataset.
%R 10.1142/9789812779519_0041
%= eprint: arXiv:0710.0701


%0 Conference Proceedings
%T Apollo:. Next Generation Lunar Laser Ranging
%A Murphy, T. W.
%A Michelsen, E. L.
%A Battat, J. B. R.
%A Stubbs, C. W.
%A Adelberger, E. G.
%A Swanson, H. E.
%A Hoyle, C. D.
%A McMillan, R. J.
%+ AA(University of California, San Diego, CASS/0424, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AB(University of California, San Diego, CASS/0424, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AC(Harvard University, Physics Department, 18 Hammond Street, Cambridge, MA 02138, USA), AD(Harvard University, Physics Department, 18 Hammond Street, Cambridge, MA 02138, USA), AE(University of Washington, Physics Department, Box 351560, Seattle, WA 98195-1560, USA), AF(University of Washington, Physics Department, Box 351560, Seattle, WA 98195-1560, USA), AG(Humboldt State University, Physics and Astronomy Department, One Harpst Street, Arcata, CA 95521-8299, USA), AH(Apache Point Observatory, 2001 Apache Point Road, Sunspot, NM 88349-0059, USA)
%J CPT and Lorentz Symmetry
%D 2008
%8 March 01, 2008
%P 192
%U https://ui.adsabs.harvard.edu/abs/2008cls..conf..192M
%X APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) is a new effort in lunar laser ranging that uses the Apollo-landed retroreflector arrays to perform tests of gravitational physics. APOLLO achieved its first range return in October, 2005, and began its science campaign the following spring. The strong signal (up to 2500 photons in a ten minute period) translates to one-millimeter random range uncertainty, constituting at least an order-of-magnitude gain over previous stations. One-millimeter range precision will translate into order-of-magnitude gains in our ability to test the weak and strong equivalence principles, the time rate of change of Newton's gravitational constant, the phenomenon of gravitomagnetism, the inverse-square law, and test new regimes of gravity and/or Lorentz violation.
%R 10.1142/9789812779519_0028


%0 Journal Article
%T Testing for Lorentz Violation: Constraints on Standard-Model-Extension Parameters via Lunar Laser Ranging
%A Battat, James B. R.
%A Chandler, John F.
%A Stubbs, Christopher W.
%+ AA(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA), AB(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA), AC(Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA)
%J Physical Review Letters
%V 99
%D 2007
%8 December 01, 2007
%P 241103
%K 04.80.-y; 06.30.Gv; 11.30.Cp; Experimental studies of gravity;
Velocity acceleration and rotation; Lorentz and Poincare invariance;
General Relativity and Quantum Cosmology; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2007PhRvL..99x1103B
%X We present constraints on violations of Lorentz invariance based on archival lunar laser-ranging (LLR) data. LLR measures the Earth-Moon separation by timing the round-trip travel of light between the two bodies and is currently accurate to the equivalent of a few centimeters (parts in 10<SUP>11</SUP> of the total distance). By analyzing this LLR data under the standard-model extension (SME) framework, we derived six observational constraints on dimensionless SME parameters that describe potential Lorentz violation. We found no evidence for Lorentz violation at the 10<SUP>-6</SUP> to 10<SUP>-11</SUP> level in these parameters. This work constitutes the first LLR constraints on SME parameters.
%R 10.1103/PhysRevLett.99.241103
%= eprint: arXiv:0710.0702
%@ 0031-9007


%0 Conference Paper
%T Sonar Determination of Environmental and Geologic Controls of Spatial-Temporal Variability in the Coal Oil Point Seep Field, California
%A Leifer, I.
%A Luyendyk, B. P.
%A Stubbs, C. C.
%A Wilson, D.
%A Kamerling, M.
%+ AA(Marine Sciences Institute, University of California, Santa Barbara, CA 93106, United States ; Institute for Crustal Studies, University of California, Santa Barbara, CA 93106, United States), AB(Department of Earth Science, University of California, Santa Barbara, CA 93106, United States ; Institute for Crustal Studies, University of California, Santa Barbara, CA 93106, United States), AC(Marine Sciences Institute, University of California, Santa Barbara, CA 93106, United States ; Department of Earth Science, University of California, Santa Barbara, CA 93106, United States), AD(Marine Sciences Institute, University of California, Santa Barbara, CA 93106, United States ; Department of Earth Science, University of California, Santa Barbara, CA 93106, United States), AE(Venoco, Inc., 6267 Carpinteria Ave. Suite 100, Carpinteria, CA 93013, United States)
%J AGU Fall Meeting Abstracts
%V 2007
%D 2007
%8 December 01, 2007
%P B53A-0930
%K 3002 Continental shelf and slope processes (4219); 3004 Gas and
hydrate systems; 4806 Carbon cycling (0428); 4820 Gases; 4894
Instruments; sensors; and techniques
%U https://ui.adsabs.harvard.edu/abs/2007AGUFM.B53A0930L
%X Marine seepage of geologic methane, CH4, is a significant yet poorly understood contribution to atmospheric greenhouse gases, and is at least 20 times as potent as CO2. Marine seeps, excluding hydrates, are ~13% of natural emissions although there is significant uncertainty due the lack of published studies. Currently, sonar is the best method for seep emission quantification. Repeat sonar surveys spanning ten years were conducted in the Coal Oil Point (COP) marine hydrocarbon seep field in southern California. The field is one of the largest in the world emitting 105m3day-1 of CH4 from ~3 km2 of seafloor at depths from 2 to 90 m. Seepage arises from the Monterey Fm reservoir, which is overlain and capped by the Sisquoc Fm. Surveys sought to locate seeps, quantify emissions, relate seepage to geological structures, and identify spatial- temporal variability in the seep field to examine controls of and environmental factors. Sonars used were wide beam 3 kHz and 3-15 kHz. To estimate emissions, RMS sonar backscatter amplitude was calculated for a fixed depth window above the seafloor and normalized to the bottom return (termed J). Then, seepage above noise along track lines was quantified for J and gridded with ~40 m resolution. The noise level was calculated from the probability distribution of J for each track line. Emissions were derived from J using a lab calibration. Results suggest geology has a controlling influence on seep spatial distribution through features including fault planes, outcrops of the contact between the Monterey and Sisquoc Fms, and folded beds. The bed and fault plane interfaces provide pathways for bubbles to migrate from the Monterey Fm through and around the capping units. Emissions show significant variability on tidal to decadal time scales and decameter to km spatial scales, including the activation and deactivation of seepage areas. Environmental factors influence seepage- e.g., emissions inversely relate to tides- with variability occurring along pathways that appear to be geologically controlled. Emission uncertainty arises from the calibration function, which showed very poor dynamic range, and the inherent geometric limitations in wide beam sonar. Further, its low spatial resolution prevents correlation of seepage with smaller geologic structures. Recent studies show high frequency multibeam sonar mapping achieves spatial resolutions &lt; 50 cm. This allows identification of individual bubble plumes, eliminating geometric uncertainty and improving dynamic range.


%0 Conference Paper
%T APOLLO: Testing Gravity with Millimeter-precision Lunar Laser Ranging
%A Battat, James
%A Murphy, Thomas
%A Adelberger, Eric
%A Hoyle, C. D.
%A McMillan, Russet
%A Michelsen, Eric
%A Nordtvedt, Kenneth
%A Orin, Adam
%A Stubbs, Christopher
%A Swanson, H. Erik
%J APS April Meeting Abstracts
%D 2007
%8 April 01, 2007
%P K12.003
%U https://ui.adsabs.harvard.edu/abs/2007APS..APRK12003B
%X Based on the discovery of the accelerating universe and dark energy, along with our inability to unite quantum mechanics and General Relativity, there is a clear need to probe deeper into gravitational physics. The Earth-Moon-Sun system is a natural, fertile laboratory for such tests. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) bounces laser light off of man-made retro-reflectors on the lunar surface to measure the Earth-Moon separation with one millimeter precision. These measurements of the lunar orbit enable improved constraints of gravitational phenomena such as the Weak Equivalence Principle, the Strong Equivalence Principle, de Sitter precession and dG/dt by an order of magnitude or better. I will describe the APOLLO project and its current status, as well as prospects for constraining PPN parameters and the universality of free-fall.


%0 Conference Paper
%T Upcoming Ground-based Surveys Designed to Constrain the Nature of the Dark Energy.
%A Stubbs, Christopher
%J APS April Meeting Abstracts
%D 2007
%8 April 01, 2007
%P J4.001
%U https://ui.adsabs.harvard.edu/abs/2007APS..APR.J4001S
%X Ground-based astronomical measurements currently provide some of the most direct constraints on the nature of the dark energy. I will briefly review the basic techniques currently being used (Type Ia supernovae, baryon acoustic oscillations...) and promising approaches being developed for the future (all-sky weak lensing, galaxy cluster abundances...). I will also describe upcoming ground-based surveys (PanSTARRS, LSST, DES...) that will contribute to our understanding of the nature of the dark energy.


%0 Journal Article
%T Cd, Ni, Pb, and Zn Concentrations in Forest Vegetation and Soils in Maine
%A McGee, Chandra J.
%A Fernandez, Ivan J.
%A Norton, Stephen A.
%A Stubbs, Constance S.
%J Water Air and Soil Pollution
%V 180
%D 2007
%8 February 01, 2007
%P 141
%U https://ui.adsabs.harvard.edu/abs/2007WASP..180..141M
%R 10.1007/s11270-006-9257-0


%0 Journal Article
%T Apollo:. a New Push in Lunar Laser Ranging
%A Murphy, T. W.
%A Michelson, E. L.
%A Orin, A. E.
%A Adelberger, E. G.
%A Hoyle, C. D.
%A Swanson, H. E.
%A Stubbs, C. W.
%A Battat, J. B.
%+ AA(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AB(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AC(Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0424, USA), AD(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, USA), AE(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, USA), AF(Center for Experimental Nuclear Physics and Astrophysics, Box 354290, University of Washington, Seattle, WA 98195-4290, USA), AG(Department of Physics, Harvard University, Cambridge, MA 02138, USA), AH(Department of Physics, Harvard University, Cambridge, MA 02138, USA)
%J International Journal of Modern Physics D
%V 16
%D 2007
%8 January 01, 2007
%P 2127
%K Gravity; laser ranging; APOLLO
%U https://ui.adsabs.harvard.edu/abs/2007IJMPD..16.2127M
%X APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) is a new effort in lunar laser ranging that uses the Apollo-landed retroreflector arrays to perform tests of gravitational physics. It achieved its first range return in October 2005, and began its science campaign the following spring. The strong signal (&gt; 2500 photons in a ten-minute period) translates to one-millimeter random range uncertainty, constituting at least an order-of-magnitude gain over previous stations. One-millimeter range precision will translate into order-of-magnitude gains in our ability to test the weak and strong equivalence principles, the time rate of change of Newton's gravitational constant, the phenomenon of gravitomagnetism, the inverse-square law, and the possible presence of extra dimensions. An outline of the APOLLO apparatus and its initial performance is presented, as well as a brief discussion on future space technologies that can extend our knowledge of gravity by orders of magnitude.
%R 10.1142/S0218271807011589
%@ 0218-2718


%0 Journal Article
%T Addressing the Crisis in Fundamental Physics
%A Stubbs, Christopher W.
%+ AA(Department of Physics and Department of Astronomy, Harvard University, 17 Oxford Street, Cambridge MA 02138, USA)
%J International Journal of Modern Physics D
%V 16
%D 2007
%8 January 01, 2007
%P 1947
%K Fundamental physics; dark energy; experiments; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2007IJMPD..16.1947S
%X The observation that the expansion of the Universe is proceeding at an ever-increasing rate, i.e. the "dark energy" problem, constitutes a crisis in fundamental physics that is as profound as the one that preceded the advent of quantum mechanics. Cosmological observations currently favor a dark energy equation-of-state parameter w = P/ρ = -1. Awkwardly, this is the value that has the least ability to discriminate between alternatives for the physics that produces the observed accelerating expansion. If this result persists we therefore run a very real risk of stagnation in our attempt to better understand the nature of this new physics, unless we uncover another piece of the dark energy puzzle. I argue that precision fundamental measurements in space have an important role in addressing this crisis.
%R 10.1142/S0218271807011711
%= eprint: arXiv:0712.2876
%@ 0218-2718


%0 Conference Paper
%T Sonar Seafloor Exploration within the Central South Atlantic Bight
%A Stubbs, C. C.
%A Sautter, L. R.
%A Harris, S. M.
%+ AA(College of Charleston, Department of Geology and Environmental Geosciences 66 George St, Charleston, SC 29412 United States), AB(College of Charleston, Department of Geology and Environmental Geosciences 66 George St, Charleston, SC 29412 United States), AC(Coastal Carolina University, Department of Marine Science PO Box 261954, Conway, SC 29528 United States)
%J AGU Fall Meeting Abstracts
%V 2006
%D 2006
%8 December 01, 2006
%P OS31B-1633
%K 3045 Seafloor morphology; geology; and geophysics; 3080 Submergence
instruments: ROV; AUV; submersibles; 3094 Instruments and techniques;
4219 Continental shelf and slope processes (3002); 4275 Remote sensing
and electromagnetic processes (0689; 2487; 3285; 4455
%U https://ui.adsabs.harvard.edu/abs/2006AGUFMOS31B1633S
%X As part of the College of Charleston's Transect Program, research cruises conducted aboard the RV Savannah of the Skidaway Institution of Oceanography and the NOAA Ship Nancy Foster have explored and sampled several localities within the central portion of the South Atlantic Bight, the continental shelf region between Florida and Cape Hatteras, NC. Klein sidescan and Kongsberg multibeam sonar arrays collected seafloor images and bathymetric data that were processed by CofC undergraduate geology researchers using Caris HIPS/SIPS software. Several of the data sets have been ground-truthed using sediment grabs, footage from ROV cameras and SCUBA videography. Two of the prominent seafloor features discovered are (1) an outcropping hard-ground shelf-edge structure approximately 650 by 150 m, with 10 m relief. It is oriented parallel to shore in water depths of 60 m. Possible geological and biological influences on the structure's origin and morphology are being explored; and (2) a meandering river channel located on the mid-shelf, where water depth is approximately 22 m. Rock and sediment samples as well as video documentation of this feature reveal a channel with 1.5 m of relief, cut into the hard-ground, and includes coarse sands and abundant river pebbles. Additional shelf hard-ground features will be presented.


%0 Conference Paper
%T Characterizing the Temporal and Spatial Stability of Atmospheric Transmission from 400 to 1050 nm.
%A Brown, L. B.
%A Stubbs, C.
%A Blondin, S.
%+ AA(Department of Physics, Harvard University, 17 Oxford St., Cambridge, MA 02138, USA), AB(Department of Physics, Harvard University, 17 Oxford St., Cambridge, MA 02138, USA), AC(Department of Astronomy, Harvard University, 60 Garden St., Cambridge, MA 02138, USA)
%J AGU Fall Meeting Abstracts
%V 2006
%D 2006
%8 December 01, 2006
%P A13B-0892
%K 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE; 0360 Radiation:
transmission and scattering
%U https://ui.adsabs.harvard.edu/abs/2006AGUFM.A13B0892B
%X The transmission function of the atmosphere is formally a function of wavelength, time, and line-of-sight. Making simplifying assumptions, such as linearity with airmass and temporal stability, enables the coarse removal of atmospheric extinction from ground-based observations of astronomical sources. However, these assumptions have not been rigorously justified to percent level precision, and small scale temporal or spatial variations could introduce non-negligible systematic errors. Systematic errors due to the atmosphere stand to inhibit the high precision measurements which are the focus of next-generation astronomical studies. We present a method of characterizing temporal and spatial variation in atmospheric transmission via spectrographic measurements of at least two standard stars simultaneously. These observations can be made on small-aperture telescopes with a simple spectrograph and can be coupled to large-aperture astronomical telescopes in order to provide real-time atmospheric diagnostics. We also present a spectrograph designed to yield efficient observations on the broad wavelength range of 400-1050 nm and our first results from this instrument.


%0 Conference Proceedings
%T Study of silicon thickness optimization for LSST
%A O'Connor, P.
%A Radeka, V.
%A Figer, D.
%A Geary, J. G.
%A Gilmore, D. K.
%A Oliver, J.
%A Stubbs, C. W.
%A Takacs, P. Z.
%A Tyson, J. A.
%+ AA(Brookhaven National Lab. (USA)), AB(Brookhaven National Lab. (USA)), AC(Space Telescope Science Institute (USA)), AD(Harvard-Smithsonian Ctr. for Astrophysics (USA)), AE(Stanford Linear Accelerator Ctr. (USA)), AF(Harvard Univ., Lab. for Particle Physics and Cosmology (USA)), AG(Harvard Univ. (USA)), AH(Brookhaven National Lab. (USA)), AI(University of California, Davis (USA))
%J Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
%V 6276
%D 2006
%8 June 01, 2006
%P 62761W
%U https://ui.adsabs.harvard.edu/abs/2006SPIE.6276E..1WO
%X Sensors for the LSST camera require high quantum efficiency (QE) extending into the near-infrared. A relatively large thickness of silicon is needed to achieve this extended red response. However, thick sensors degrade the point spread function (PSF) due to diffusion and to the divergence of the fast f/1.25 beam. In this study we examine the tradeoff of QE and PSF as a function of thickness, wavelength, temperature, and applied electric field for fully-depleted sensors. In addition we show that for weakly absorbed long-wavelength light, optimum focus is achieved when the beam waist is positioned slightly inside the silicon.
%R 10.1117/12.673393
%@ 0277-786X


%0 Conference Proceedings
%T The LSST sensor technologies studies
%A Geary, J.
%A Figer, D.
%A Gilmore, D. K.
%A O'Connor, P.
%A Oliver, J.
%A Radeka, V.
%A Stubbs, C.
%A Takas, P.
%A Tyson, J. A.
%+ AA(Harvard-Smithsonian Ctr. for Astrophysics (USA)), AB(Space Telescope Science Institute (USA)), AC(Stanford Linear Accelerator Ctr. (USA)), AD(Brookhaven National Lab. (USA)), AE(Harvard Univ. (USA)), AF(Brookhaven National Lab. (USA)), AG(Harvard Univ. (USA)), AH(Brookhaven National Lab. (USA)), AI(University of California, Davis (USA))
%J Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
%V 6276
%D 2006
%8 June 01, 2006
%P 627601
%U https://ui.adsabs.harvard.edu/abs/2006SPIE.6276E..01G
%X The LSST project has embarked on an aggressive new program to develop the next generation of silicon imagers for the visible and near-IR spectral regions. In order to better understand and solve some of the technology issues prior to development and mass-production for the huge LSST focal plane, a number of contracts have been written to imager firms to explore specific areas of technology uncertainty. We expect that these study contracts will do much toward reducing risk and uncertainty going into the next phase of development, the prototype production of the final large LSST imager.
%R 10.1117/12.673291
%@ 0277-786X


%0 Conference Proceedings
%T Calibration techniques for next-generation astronomical systems
%A Slater, S.
%A Stubbs, C. W.
%A Tonry, J. L.
%A Masiero, J. R.
%A Smith, R. C.
%+ AA(Harvard Univ. (USA)), AB(Harvard Univ. (USA)), AC(Institute for Astronomy, University of Hawaii (USA)), AD(Institute for Astronomy, University of Hawaii (USA)), AE(Cerro Tololo Inter-American Observatory (Chile))
%J Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
%V 6269
%D 2006
%8 June 01, 2006
%P 626921
%U https://ui.adsabs.harvard.edu/abs/2006SPIE.6269E..21S
%X Historically, few astronomical measurements have required sub-percent accuracy in photometry. Measuring SNIa fluxes in order to determine cosmological parameters, however, often requires the comparison of images from different telescopes, and at different redshifts. This can introduce a myriad of sources of error. Conventional methods of data reduction are intrinsically flawed, either making assumptions about the effects of wavelength dependence in the response function of the system or, when K-corrections are not performed, neglecting them altogether. We consider the advantages of a method utilizing a direct, spectrally-resolved measurement of the entire system's response function relative to a calibrated photodiode.
%R 10.1117/12.670144
%@ 0277-786X


%0 Conference Proceedings
%T Calibrations of LSST camera and telescope systems
%A Burke, David
%A Axelrod, Tim
%A Claver, Chuck
%A Frank, James
%A Geary, John
%A Gilmore, Kirk
%A Ivezic, Zeljko
%A Krabbendam, Victor
%A Monet, David
%A O'Connor, Paul
%A Oliver, John
%A Olszewski, Ed
%A Pinto, Philip
%A Saha, Abhijit
%A Smith, Chris
%A Stubbs, Christopher
%A Takacs, Peter
%A Tyson, Anthony
%+ AA(Stanford Linear Accelerator Ctr. (USA)), AB(Steward Observatory (USA)), AC(National Optical Astronomy Observatory (USA)), AD(Brookhaven National Lab. (USA)), AE(Harvard-Smithsonian Ctr. for Astrophysics (USA)), AF(Stanford Linear Accelerator Ctr. (USA)), AG(University of Washington (USA)), AH(National Optical Astronomy Observatory (USA)), AI(U.S. Naval Observatory (USA)), AJ(Brookhaven National Lab. (USA)), AK(Harvard-Smithsonian Ctr. for Astrophysics (USA)), AL(Steward Observatory (USA)), AM(Steward Observatory (USA)), AN(National Optical Astronomy Observatory (USA)), AO(National Optical Astronomy Observatory (USA)), AP(Harvard-Smithsonian Ctr. for Astrophysics (USA)), AQ(Brookhaven National Lab. (USA)), AR(University of California/Davis (USA))
%J Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series
%V 6267
%D 2006
%8 June 01, 2006
%P 626715
%U https://ui.adsabs.harvard.edu/abs/2006SPIE.6267E..15B
%X Science studies made by the Large Synoptic Survey Telescope will reach systematic limits in nearly all cases. Requirements for accurate photometric measurements are particularly challenging. Advantage will be taken of the rapid cadence and pace of the LSST survey to use celestial sources to monitor stability and uniformity of photometric data. A new technique using a tunable laser is being developed to calibrate the wavelength dependence of the total telescope and camera system throughput. Spectroscopic measurements of atmospheric extinction and emission will be made continuously to allow the broad-band optical flux observed in the instrument to be corrected to flux at the top of the atmosphere. Calibrations with celestial sources will be compared to instrumental and atmospheric calibrations.
%R 10.1117/12.673271
%@ 0277-786X


%0 Conference Proceedings
%T Project status of the 8.4-m LSST
%A Claver, Charles F.
%A Sweeney, Donald W.
%A Tyson, John A.
%A Althouse, Bryan
%A Axelrod, Timothy S.
%A Cook, Kem H.
%A Daggert, Larry G.
%A Kantor, Jeffrey C.
%A Kahn, Steven M.
%A Krabbendam, Victor L.
%A Pinto, Philip
%A Sebag, Jacques
%A Stubbs, C.
%A Wolff, Sidney C.
%+ AA(National Optical Astronomy Observatory, USA), AB(LSST Corp., USA), AC(University of California/Davis, USA), AD(Stanford Linear Accelerator Ctr., USA), AE(Steward Observatory/University of Arizona, USA), AF(Lawrence Livermore National Lab., USA), AG(National Optical Astronomy Observatory, USA), AH(LSST Corp., USA), AI(Stanford Linear Accelerator Ctr., USA), AJ(National Optical Astronomy Observatory, USA), AK(Steward Observatory/University of Arizona, USA), AL(National Optical Astronomy Observatory, USA), AM(Harvard University, USA), AN(National Optical Astronomy Observatory, USA)
%J Ground-based Telescopes
%V 5489
%D 2004
%8 October 01, 2004
%P 705
%U https://ui.adsabs.harvard.edu/abs/2004SPIE.5489..705C
%X The 8.4m Large Synoptic Survey Telescope (LSST) is a wide-field telescope facility that will add a qualitatively new capability in astronomy. For the first time, the LSST will provide time-lapse digital imaging of faint astronomical objects across the entire sky. The LSST has been identified as a national scientific priority by diverse national panels, including multiple National Academy of Sciences committees. This judgment is based upon the LSST's ability to address some of the most pressing open questions in astronomy and fundamental physics, while driving advances in data-intensive science and computing. The LSST will provide unprecedented 3-dimensional maps of the mass distribution in the Universe, in addition to the traditional images of luminous stars and galaxies. These mass maps can be used to better understand the nature of the newly discovered and utterly mysterious Dark Energy that is driving the accelerating expansion of the Universe. The LSST will also provide a comprehensive census of our solar system, including potentially hazardous asteroids as small as 100 meters in size. The LSST facility consists of three major subsystems: 1) the telescope, 2) the camera and 3) the data processing system. The baseline design for the LSST telescope is a 8.4m 3-mirror design with a 3.5 degree field of view resulting in an A-Omega product (etendue) of 302deg<SUP>2</SUP>m<SUP>2</SUP>. The camera consists of 3-element transmisive corrector producing a 64cm diameter flat focal plane. This focal plane will be populated with roughly 3 billion 10μm pixels. The data processing system will include pipelines to monitor and assess the data quality, detect and classify transient events, and establish a large searchable object database. We report on the status of the designs for these three major LSST subsystems along with the overall project structure and management.
%R 10.1117/12.561728
%@ 0277-786X


%0 Journal Article
%T Testing Gravity via Next-Generation Lunar Laser-Ranging
%A Murphy, T. W.
%A Adelberger, E. G.
%A Strasburg, J. D.
%A Stubbs, C. W.
%A Nordtvedt, K.
%+ AA(University of California San Diego, 9500 Gilman Dr.-0424, La Jolla, CA 92093-0424), AB(Box 361560, University of Washington, Seattle, WA 98195-1560), AC(Box 361560, University of Washington, Seattle, WA 98195-1560), AD(Harvard University, 17 Oxford St., Cambridge, MA 02138), AE(Northwest Analysis, 118 Sourdough Ridge Road, Bozeman, MT 59715)
%J Nuclear Physics B Proceedings Supplements
%V 134
%D 2004
%8 September 01, 2004
%P 155
%U https://ui.adsabs.harvard.edu/abs/2004NuPhS.134..155M
%X Lunar laser ranging has a long history of performing the most precise tests of various gravitational phenomena, dating from the placement of retroreflector arrays on the lunar surface by the Apollo astronauts. Gravity is the least well understood of the fundamental forces of nature, our current model being incompatible with quantum mechanics. We must therefore push our tests of gravity further, with the expectation that general relativity will fail to reproduce exactly measurements of sufficient precision. We aim to improve lunar ranging performance by an order-of-magnitude, resulting in comparable sensitivity gains in various tests of the basic nature of gravity. Here we describe the scientific motivation and techniques behind this next-generation lunar ranging effort, APOLLO.
%R 10.1016/j.nuclphysbps.2004.08.025
%@ 0920-5632


%0 Conference Proceedings
%T Visible Imaging Fourier Transform Spectrometer: Design and Calibration
%A Wishnow, Edward H.
%A Wurtz, Ronald E.
%A Blais-Ouellette, Sebastien
%A Cook, Kem H.
%A Carr, Dennis J.
%A Lewis, Isabella T.
%A Grandmont, Frederic
%A Stubbs, Christopher W.
%+ AA(Lawrence Livermore National Lab., USA), AB(Lawrence Livermore National Lab., USA), AC(Université de Montreal, Canada), AD(Lawrence Livermore National Lab., USA), AE(Lawrence Livermore National Lab., USA), AF(Lawrence Livermore National Lab., USA), AG(Univ. Laval, Canada and ABB-Bomem Inc., Canada), AH(University of Washington, USA)
%J Instrument Design and Performance for Optical/Infrared Ground-based Telescopes
%V 4841
%D 2003
%8 March 01, 2003
%P 1067
%U https://ui.adsabs.harvard.edu/abs/2003SPIE.4841.1067W
%X We present details of the design, operation and calibration of an astronomical visible-band imaging Fourier transform spectrometer (IFTS). This type of instrument produces a spectrum for every pixel in the field of view where the spectral resolution is flexible. The instrument is a dual-input/dual-output Michelson interferometer coupled to the 3.5 meter telescope at the Apache Point Observatory. Imaging performance, and interferograms and spectra from calibration sources and standard stars are discussed.
%R 10.1117/12.461512
%@ 0277-786X


%0 Conference Proceedings
%T The Galactic Exoplanet Survey Telescope (GEST)
%A Bennett, David P.
%A Bally, John
%A Bond, I.
%A Cheng, Ed
%A Cook, Kem
%A Deming, Drake
%A Garnavich, P.
%A Griest, Kim
%A Jewitt, David
%A Kaiser, Nick
%A Lauer, Tod R.
%A Lunine, Jonathan
%A Luppino, Gerard
%A Mather, John C.
%A Minniti, Dante
%A Peale, Stanton J.
%A Rhie, Sun H.
%A Rhodes, Jason
%A Schneider, Jean
%A Sonneborn, George
%A Stevenson, Robert
%A Stubbs, Christopher
%A Tenerelli, Domenick
%A Woolf, Neville
%A Yock, Phillip
%+ AA(University of Notre Dame, USA), AB(University of Colorado/Boulder, USA), AC(University of Auckland (New Zealand)), AD(NASA Goddard Space Flight Center, USA), AE(Lawrence Livermore National Lab., USA), AF(NASA Goddard Space Flight Ctr., USA), AG(University of Notre Dame, USA), AH(University of California/San Diego, USA), AI(University of Hawaii/Manoa, USA), AJ(University of Hawaii/Manoa, USA), AK(National Optical Astronomy Observatory, USA), AL(University of Arizona, USA), AM(University of Hawaii/Manoa, USA), AN(NASA Goddard Space Flight Ctr., USA), AO(Pontifica Univ. Catolica de Chile, Chile), AP(University of California/Santa Barbara, USA), AQ(University of Notre Dame, USA), AR(NASA Goddard Space Flight Ctr., USA), AS(Observatoire de Paris-Meudon, France), AT(NASA Goddard Space Flight Ctr., USA), AU(University of Notre Dame, USA), AV(University of Washington, USA), AW(Lockheed Martin Space Systems Co., USA), AX(University of Arizona, USA), AY(University of Auckland (New Zealand))
%J Future EUV/UV and Visible Space Astrophysics Missions and Instrumentation.
%V 4854
%D 2003
%8 February 01, 2003
%P 141
%K Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2003SPIE.4854..141B
%X The Galactic Exoplanet Survey Telescope (GEST) will observe a 2 square degree field in the Galactic bulge to search for extra-solar planets using a gravitational lensing technique. This gravitational lensing technique is the only method employing currently available technology that can detect Earth-mass planets at high signal-to-noise, and can measure the abundance of terrestrial planets as a function of Galactic position. GEST's sensitivity extends down to the mass of Mars, and it can detect hundreds of terrestrial planets with semi-major axes ranging from 0.7 AU to infinity. GEST will be the first truly comprehensive survey of the Galaxy for planets like those in our own Solar System.
%R 10.1117/12.459816
%= eprint: arXiv:astro-ph/0209435
%@ 0277-786X


%0 Conference Proceedings
%T Gallery of datacubes obtained with the Livermore imaging Fourier transform spectrometer
%A Wurtz, Ronald E.
%A Wishnow, Edward H.
%A Blais-Ouellette, Sebastien
%A Cook, Kem H.
%A Holden, Bradford P.
%A Carr, Dennis J.
%A Stubbs, Christopher W.
%+ AA(Lawrence Livermore National Lab., USA), AB(Lawrence Livermore National Lab., USA), AC(Lawrence Livermore National Lab., USA; Univ. de Montreal, Canada), AD(Lawrence Livermore National Lab., USA), AE(Lawrence Livermore National Lab., USA; University of California/Davis, USA), AF(Lawrence Livermore National Lab., USA), AG(University of Washington, USA)
%J Specialized Optical Developments in Astronomy
%V 4842
%D 2003
%8 February 01, 2003
%P 352
%U https://ui.adsabs.harvard.edu/abs/2003SPIE.4842..352W
%X We have acquired spatial-spectral datacubes of astronomical objects using the Livermore visible-band imaging Fourier transform spectrometer at Apache Point Observatory. Each raw datacube contains hundreds of thousands of spectral interferograms. We present in-progress demonstrations of these observations.
%R 10.1117/12.458083
%@ 0277-786X


%0 Conference Proceedings
%T Real-time Time-variability Analysis of GB to TB Datasets: Experience from SuperMACHO and Supernova projects at NOAO/CTIO
%A Smith, Chris
%A Rest, Armin
%A Hiriart, Rafael
%A Becker, Andrew
%A Stubbs, Christopher W.
%A Valdes, Francisco G.
%A Suntzeff, Nicholas
%+ AA(National Optical Astronomy Observatory, Chile), AB(University of Washington, USA), AC(National Optical Astronomy Observatory, Chile), AD(Lucent Technologies/Bell Labs., USA), AE(University of Washington, USA), AF(National Optical Astronomy Observatoires, USA), AG(National Optical Astronomy Observatoires, Chile)
%J Survey and Other Telescope Technologies and Discoveries
%V 4836
%D 2002
%8 December 01, 2002
%P 395
%U https://ui.adsabs.harvard.edu/abs/2002SPIE.4836..395S
%X The era of large survey datasets has arrived, and the era of large survey telescope projects is upon us. Many of these new telescope projects will not only produce large datasets, they will produce datasets that require real-time astronomical analysis, including object detection, photometry, and classification. These datasets promise to open new horizons in the exploration of the time domain in astrophysical systems on large scales. But to fulfill this promise, the projects must design and develop data management systems on a much larger scale (many Terabytes per day continuously) than has previously been achieved in astronomy. Working together, NOAO and the University of Washington are developing prototype pipeline systems to explore the issues involved in real-time time-variability analysis. These efforts are not simply theoretical exercises, but rather are driven by NOAO Survey programs which are generating large data flows. Our survey projects provide a science-driven testbed of data management strategies needed for future initiatives such as the Large Synoptic Survey Telescope and other large-scale astronomical data production systems.
%R 10.1117/12.461391
%@ 0277-786X


%0 Conference Proceedings
%T Lunar laser ranging using avalanche photodiode (APD) arrays
%A Strasburg, Jana D.
%A Murphy, Thomas W., Jr.
%A Stubbs, Christopher W.
%A Adelberger, Eric G.
%A Miller, D. W.
%A Angle, J. I.
%+ AA(University of Washington, USA), AB(University of Washington, USA), AC(University of Washington, USA), AD(University of Washington, USA), AE(Carleton College, USA), AF(University of Washington, USA)
%J Survey and Other Telescope Technologies and Discoveries
%V 4836
%D 2002
%8 December 01, 2002
%P 387
%U https://ui.adsabs.harvard.edu/abs/2002SPIE.4836..387S
%X The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) will improve range measurements to the moon by at least an order-of-magnitude, with the goal of achieving millimeter precision. Lunar ranging provides the most stringent tests of Einstein's strong equivalence principle, as well as placing the tightest constraints on the time evolution of Newton's gravitational constant. At the heart of APOLLO is an integrated array of avalanche photodiodes (APDs) developed at MIT Lincoln Laboratories. These devices are capable of detecting the arrival of a single photon with high temporal precision (&lt; 100 ps), with detection efficiencies as high as 50%. The thin APD arrays have breakdown voltages in the neighborhood of 25 volts, active areas 20, 30, or 40 microns in diameter, placed on 100 micron centers in a square pattern. APOLLO will initially work with a 4×4 array, but may eventually upgrade to a larger format. The potential use of APD array technology in other areas of astronomy is briefly discussed.
%R 10.1117/12.459474
%@ 0277-786X


%0 Conference Proceedings
%T Deep lens survey
%A Wittman, David M.
%A Tyson, J. Anthony
%A Dell'Antonio, Ian P.
%A Becker, Andrew
%A Margoniner, Vera
%A Cohen, Judith G.
%A Norman, D.
%A Loomba, D.
%A Squires, G.
%A Wilson, Gillian
%A Stubbs, Christopher W.
%A Hennawi, J.
%A Spergel, David N.
%A Boeshaar, P.
%A Clocchiatti, A.
%A Hamuy, M.
%A Bernstein, G.
%A Gonzalez, A.
%A Guhathakurta, Puragra
%A Hu, W.
%A Seljak, U.
%A Zaritsky, Dennis
%+ AA(Lucent Technologies/Bell Labs., USA), AB(Lucent Technologies/Bell Labs., USA), AC(Brown Univ., USA), AD(Lucent Technologies/Bell Labs., USA), AE(Lucent Technologies/Bell Labs., USA), AF(California Institute of Technology, USA), AG(CTIO, USA), AH(University of New Mexico, USA), AI(California Institute of Technology, USA), AJ(Brown Univ. and California Institute of Technology, USA), AK(University of Washington, USA), AL(Princeton Univ., USA), AM(Princeton Univ., USA), AN(Drew Univ., USA), AO(PUCC, USA), AP(Observatoires of the Carnegie Foundation of Washington, USA), AQ(University of Pennsylvania, USA), AR(University of Florida, USA), AS(Lick Observatory/University of California/Santa Cruz, USA), AT(University of Chicago, USA), AU(Princeton Univ., USA), AV(Steward Observatory/University of Arizona, USA)
%J Survey and Other Telescope Technologies and Discoveries
%V 4836
%D 2002
%8 December 01, 2002
%P 73
%K Astrophysics
%U https://ui.adsabs.harvard.edu/abs/2002SPIE.4836...73W
%X The Deep Lens Survey (DLS) is a deep BV Rz' imaging survey of seven 2°×2° degree fields, with all data to be made public. The primary scientific driver is weak gravitational lensing, but the survey is also designed to enable a wide array of other astrophysical investigations. A unique feature of this survey is the search for transient phenomena. We subtract multiple exposures of a field, detect differences, classify, and release transients on the Web within about an hour of observation. Here we summarize the scientific goals of the DLS, field and filter selection, observing techniques and current status, data reduction, data products and release, and transient detections. Finally, we discuss some lessons which might apply to future large surveys such as LSST.
%R 10.1117/12.457348
%= eprint: arXiv:astro-ph/0210118
%@ 0277-786X


%0 Journal Article
%T LISA and its in-flight test precursor SMART-2
%A Vitale, S.
%A Bender, P.
%A Brillet, A.
%A Buchman, S.
%A Cavalleri, A.
%A Cerdonio, M.
%A Cruise, M.
%A Cutler, C.
%A Danzmann, K.
%A Dolesi, R.
%A Folkner, W.
%A Gianolio, A.
%A Jafry, Y.
%A Hasinger, G.
%A Heinzel, G.
%A Hogan, C.
%A Hueller, M.
%A Hough, J.
%A Phinney, S.
%A Prince, T.
%A Richstone, D.
%A Robertson, D.
%A Rodrigues, M.
%A Rüdiger, A.
%A Sandford, M.
%A Schilling, R.
%A Shoemaker, D.
%A Schutz, B.
%A Stebbins, R.
%A Stubbs, C.
%A Sumner, T.
%A Thorne, K.
%A Tinto, M.
%A Touboul, P.
%A Ward, H.
%A Weber, W.
%A Winkler, W.
%+ AA(Dipartimento di Fisica, Università di Trento I-38050, Povo, Trento, Italy), AB(Joint Institutes for Laboratory Astrophysics, Boulder, Colorado, USA), AC(Observatoire de la Côte d'Azur, Nice, France), AD(W.W. Hansen Experimental Physics Labs, Stanford University, Stanford, California USA), AE(Dipartimento di Fisica, Università di Trento I-38050, Povo, Trento, Italy), AF(Dipartimento di Fisica Università di Padova, Italy), AG(Department of Physics &amp; Astronomy, University of Birmingham, UK), AH(Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) Golm, Germany), AI(Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) and Universität Hannover, Hannover, Germany), AJ(Dipartimento di Fisica, Università di Trento I-38050, Povo, Trento, Italy), AK(Jet Propulsion Laboratory, Pasadena, California, USA), AL(ESA-ESTEC, Nordwijk, The Netherlands), AM(ESA-ESTEC, Nordwijk, The Netherlands), AN(Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), AO(Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) and Universität Hannover, Hannover, Germany), AP(Departments of Physics and Astronomy, University of Washington, Seattle, Washington, USA), AQ(Dipartimento di Fisica, Università di Trento I-38050, Povo, Trento, Italy), AR(Department of Physics and Astronomy, University of Glasgow, Glasgow, UK), AS(California Institute of Technology, Pasadena, California, USA), AT(California Institute of Technology, Pasadena, California, USA), AU(Department of Astronomy, University of Michigan, Ann Arbor, Michigan, USA), AV(Department of Physics and Astronomy, University of Glasgow, Glasgow, UK), AW(ONERA, Châtillon, France), AX(Max-Planck-Institut für Quantenoptik, Garching, Germany), AY(Rutherford Appleton Laboratory, Chilton-Didcot,UK), AZ(Max-Planck-Institut für Quantenoptik, Garching, Germany), BA(Massachusetts Institute of Technology, Cambridge, Massachusetts, USA), BB(Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) Golm, Germany), BC(NASA Goddard Space Flight Center, Greenbelt, Maryland, USA), BD(Departments of Physics and Astronomy, University of Washington, Seattle, Washington, USA), BE(The Blackett Laboratory, Imperial College of Science, Technology &amp; Medicine, London, UK), BF(California Institute of Technology, Pasadena, California, USA), BG(Jet Propulsion Laboratory, Pasadena, California, USA), BH(ONERA, Châtillon, France), BI(Department of Physics and Astronomy, University of Glasgow, Glasgow, UK), BJ(Dipartimento di Fisica, Università di Trento I-38050, Povo, Trento, Italy), BK(Max-Planck-Institut für Quantenoptik, Garching, Germany)
%J Nuclear Physics B Proceedings Supplements
%V 110
%D 2002
%8 July 01, 2002
%P 209
%U https://ui.adsabs.harvard.edu/abs/2002NuPhS.110..209V
%X LISA will be the first space-home gravitational wave observatory. It aims to detect gravitational waves in the 0.1 mHz÷1 Hz range from sources including galactic binaries, super-massive black-hole binaries, capture of objects by super-massive black-holes and stochastic background. LISA is an ESA approved Cornerstone Mission foreseen as a joint ESA-NASA endeavour to be launched in 2010-11. The principle of operation of LISA is based on laser ranging of test-masses under pure geodesic motion. Achieving pure geodesic motion at the level requested for LISA, 3×10 <SUP>-15</SUP> ms <SUP>-2</SUP>/√Hz at 0.1 mHz, is considered a challenging technological objective. To reduce the risk, both ESA and NASA are pursuing an in-flight test of the relevant technology. The goal of the test is to demonstrate geodetic motion within one order of magnitude from the LISA performance. ESA has given this test as the primary goal of its technology dedicated mission SMART-2 with a launch in 2006. This paper describes the basics of LISA, its key technologies, and its in-flight precursor test on SMART-2.
%R 10.1016/S0920-5632(02)01484-6
%@ 0920-5632


%0 Conference Paper
%T Constraining the Weight of Gravity: A Test of the Strong Equivalence Principle using Lunar Laser-Ranging
%A Strasburg, Jana
%A Murphy, Tom
%A Stubbs, Christopher
%A Adelberger, Eric
%+ AA(University of Washington), AB(University of Washington), AC(University of Washington), AD(University of Washington)
%J APS Northwest Section Meeting Abstracts
%V 46
%D 2001
%8 May 01, 2001
%P F1.009
%U https://ui.adsabs.harvard.edu/abs/2001APS..NWS.F1009S
%X The University of Washington has recently embarked on a Lunar Laser-Ranging campaign aimed at measuring the earth-moon separation with millimeter precision. This will be the strongest test to date of the Strong Equivalence Principle and other fundamental gravitational questions. The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) will employ the 3.5 meter telescope at the Apache Point Observatory in southern New Mexico. This instrument will result in the detection of several return photons per outgoing laser pulse, a dramatic improvement over current signal rates. This improved signal rate will yield a better understanding of the systematic errors involved as well as allow for operation during high-background conditions such as the full moon and twilight. In order to deal with the high signal rate, an array of avalanche photodiodes will oversample the return spot and time-tag each return photon. A precision gravimeter will also be placed at the site to measure the vertical crustal deformation due to geophysical effects including solid earth tides and ocean, atmospheric and ground water loading. These measurements will be used to constrain the modeling that will ultimately produce the final result.


%0 Conference Paper
%T A Next Generation Microlensing Search for Dark Matters
%A Stubbs, Christopher
%+ AA(University of Washington, Seattle)
%J APS Northwest Section Meeting Abstracts
%D 1999
%8 May 01, 1999
%P B2.02
%U https://ui.adsabs.harvard.edu/abs/1999APS..NWS..B202S


%0 Journal Article
%T Supernova Limits on the Cosmic Equation of State
%A Garnavich, Peter M.
%A Jha, Saurabh
%A Challis, Peter
%A Clocchiatti, Alejandro
%A Diercks, Alan
%A Filippenko, Alexei V.
%A Gilliland, Ron L.
%A Hogan, Craig J.
%A Kirshner, Robert P.
%A Leibundgut, Bruno
%A Phillips, M. M.
%A Reiss, David
%A Riess, Adam G.
%A Schmidt, Brian P.
%A Schommer, Robert A.
%A Smith, R. Chris
%A Spyromilio, Jason
%A Stubbs, Chris
%A Suntzeff, Nicholas B.
%A Tonry, John
%A Carroll, Sean M.
%+ AA(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.), AB(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.), AC(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.), AD(Departmento de Astronomía y Astrophisica, Pontificia Universidad Católica, Casilla 104, Santiago 22, Chile.), AE(Department of Astronomy, University of Washington, Seattle, WA 98195.), AF(Department of Astronomy, University of California, Berkeley, CA 94720-3411.), AG(Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218.), AH(Department of Astronomy, University of Washington, Seattle, WA 98195.), AI(Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.), AJ(European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching, Germany.), AK(Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile.), AL(Department of Astronomy, University of Washington, Seattle, WA 98195.), AM(Department of Astronomy, University of California, Berkeley, CA 94720-3411.), AN(Mount Stromlo and Siding Spring Observatory, Private Bag, Weston Creek P.O., Australia.), AO(Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile.), AP(University of Michigan, Department of Astronomy, 834 Dennison, Ann Arbor, MI 48109.), AQ(European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching, Germany.), AR(Department of Astronomy, University of Washington, Seattle, WA 98195.), AS(Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile.), AT(Institute for Astronomy, University of Hawaii, Manoa, HI 96822.), AU(Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106.)
%J The Astrophysical Journal
%V 509
%D 1998
%8 December 01, 1998
%P 74
%K COSMOLOGY: OBSERVATIONS; COSMOLOGY: THEORY; STARS: SUPERNOVAE:
GENERAL; Cosmology: Observations; Cosmology: Theory; Stars: Supernovae:
General; Astrophysics; General Relativity and Quantum Cosmology; High
Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1998ApJ...509...74G
%X We use Type Ia supernovae studied by the High-z Supernova Search Team to constrain the properties of an energy component that may have contributed to accelerating the cosmic expansion. We find that for a flat geometry the equation-of-state parameter for the unknown component, α<SUB>x</SUB> = P<SUB>x</SUB>/ρ<SUB>x</SUB>, must be less than -0.55 (95% confidence) for any value of Ω<SUB>m</SUB>, and it is further limited to α<SUB>x</SUB> &lt; -0.60 (95% confidence) if Ω<SUB>m</SUB> is assumed to be greater than 0.1. These values are inconsistent with the unknown component being topological defects such as domain walls, strings, or textures. The supernova (SN) data are consistent with a cosmological constant (α<SUB>x</SUB> = -1) or a scalar field that has had, on average, an equation-of-state parameter similar to the cosmological constant value of -1 over the redshift range of z ~ 1 to the present. SN and cosmic microwave background observations give complementary constraints on the densities of matter and the unknown component. If only matter and vacuum energy are considered, then the current combined data sets provide direct evidence for a spatially flat universe with Ω<SUB>tot</SUB> = Ω<SUB>m</SUB> + Ω<SUB>Λ</SUB> = 0.94 +/- 0.26 (1 σ).
%R 10.1086/306495
%= eprint: arXiv:astro-ph/9806396
%@ 0004-637X


%0 Conference Proceedings
%T CCD mosaics--past, present, and future: a review
%A Luppino, Gerard A.
%A Tonry, John L.
%A Stubbs, Christopher W.
%+ AA(University of Hawaii/Honolulu), AB(University of Washington)
%J Optical Astronomical Instrumentation
%V 3355
%D 1998
%8 July 01, 1998
%P 469
%U https://ui.adsabs.harvard.edu/abs/1998SPIE.3355..469L
%X We have entered an era of large CCD mosaic camera construction with many observatories developing large mosaic focal planes for wide field cameras and spectrographs. In this review, we outline the history of CCD mosaic development, describe the current state of the art while illustrating the many projects underway, and attempt to peer into the future.
%R 10.1117/12.316778
%@ 0277-786X


%0 Conference Proceedings
%T MACHO data pipeline
%A Axelrod, Timothy S.
%A Allsman, R. A.
%A Quinn, Peter J.
%A Alcock, Charles R.
%A Alves, D.
%A Becker, A.
%A Bennett, D. P.
%A Cook, Kenneth H.
%A Drake, A.
%A Freeman, K. C.
%A Griest, Kim
%A Lehner, M.
%A Marshall, Stuart L.
%A Minniti, D.
%A Peterson, Bruce A.
%A Pratt, M. R.
%A Rodgers, A. W.
%A Stubbs, Christopher W.
%A Sutherland, W. J.
%A Tomaney, A.
%A Vandehei, T.
%A Welch, D.
%+ AA(Mt. Stromlo and Siding Springs Observatory), AB(Australian National University), AC(European Southern Observatory), AD(Lawrence Livermore National Lab.), AE(University of Washington), AF(McMaster University), AG(Lawrence Livermore National Lab.), AH(Mt. Stromlo and Siding Springs Observatory), AI(University of California/San Diego), AJ(Lawrence Livermore National Lab.), AK(Mt. Stromlo and Siding Springs Observatory), AL(University of Washington), AM(Mt. Stromlo and Siding Springs Observatory), AN(University of Washington), AO(Oxford University), AP(University of Washington), AQ(University of California/San Diego), AR(McMaster University)
%J Observatory Operations to Optimize Scientific Return
%V 3349
%D 1998
%8 July 01, 1998
%P 152
%U https://ui.adsabs.harvard.edu/abs/1998SPIE.3349..152A
%X The MACHO experiment is searching for dark matter in the halo of the Galaxy by monitoring more than 50 million stars in the LMC, SMC, and Galactic bulge for gravitational microlensing events. The hardware consists of a 50 inch telescope, a two-color 32 megapixel ccd camera and a network of computers. On clear nights the system generates up to 8 GB of raw data and 1 GB of reduced data. The computer system is responsible for all realtime control tasks, for data reduction, and for storing all data associated with each observation in a database. The subject of this paper is the software system that handles these functions. It is an integrated system controlled by Petri nets that consists of multiple processes communicating via mailboxes and a bulletin board. The system is highly automated, readily extensive, and incorporates flexible error recovery capabilities. It is implemented with C++ in a Unix environment.
%R 10.1117/12.316482
%@ 0277-786X


%0 Conference Proceedings
%T Optical imaging of gamma-ray bursts with the LONEOS telescope
%A Wagner, R. M.
%A Bowell, E.
%A Cook, K. H.
%A Howell, S. B.
%A Koehn, B. W.
%A Shrader, C. R.
%A Starrfield, S. G.
%A Stubbs, C. W.
%+ AA(Department of Astronomy, Ohio State University), AB(Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, Arizona 86001), AC(Lawrence Livermore National Laboratory, V Division, MS L-401, PO Box 808, Livermore, California 94550), AD(Department of Physics and Astronomy, University of Wyoming, PO Box 3905, University Station, Laramie, Wyoming 82071), AE(Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, Arizona 86001), AF(NASA/GSFC, Laboratory for High Energy Astrophysics, Code 660.1, Greenbelt, Maryland 20771), AG(Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85287-1504), AH(Department of Astronomy, University of Washington, Seattle, Washington 98195-1580)
%J Gamma-Ray Bursts, 4th Hunstville Symposium
%V 428
%D 1998
%8 May 01, 1998
%P 869
%K 95.55.Cs; 98.70.Rz; Ground-based ultraviolet optical and infrared
telescopes; gamma-ray sources; gamma-ray bursts
%U https://ui.adsabs.harvard.edu/abs/1998AIPC..428..869W
%X The optical identification of gamma-ray bursts discovered and localized by BACODINE/LOCBURST using the Lowell Observatory Near-Earth Object Search (LONEOS) 58-cm Schmidt-type telescope and mosaic CCD camera is described. In its final form, LONEOS images 10 square degrees of the sky (3.2°×3.2°) to ~22nd mag (2σ) in a 5 minute integration. Identification of optical transients will be based on variability by comparison with subsequent images or previous scans of the region. To date, optical images have been obtained of three BATSE triggers processed by LOCBURST for development and evaluation purposes.
%R 10.1063/1.55459
%@ 0094-243X


%0 Conference Proceedings
%T Method for extending the dynamic range of CCD instruments
%A Stubbs, Christopher W.
%A Doherty, Peter E.
%A Diercks, Alan H.
%+ AA(Univ. of Washington, USA), AB(Univ. of Washington, USA), AC(Univ. of Washington, USA)
%J Solid State Sensor Arrays: Development and Applications II
%V 3301
%D 1998
%8 April 01, 1998
%P 75
%U https://ui.adsabs.harvard.edu/abs/1998SPIE.3301...75S
%X Charge coupled devices (CCDs) are the detector of choice for instruments that detect low levels of light for wavelengths 300 nm &lt;EQ (lambda) &lt;EQ 1100 nm. Contemporary devices have read noise level equivalents of a few electrons, and the ability to store over 100,000 electrons per pixel. In order to take full advantage of these characteristics, while ensuring that digital quantization noise will not dominate over readout noise, the dynamic range of the readout system must exceed 18 bits. We present a simple scheme that exploits the fact that Poisson noise dominates the error budget in most contemporary CCD systems in order to achieve an effective dynamic range of over 20 bits by suing dual 16 bit A/D converters of different sensitivity.
%R 10.1117/12.304569
%@ 0277-786X


%0 Journal Article
%T The MACHO Project Large Magellanic Cloud Microlensing Results from the First Two Years and the Nature of the Galactic Dark Halo
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Becker, A. C.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Lehner, M. J.
%A Marshall, S. L.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A Welch, D. L.
%+ AA(Lawrence Livermore National Laboratory, Livermore, CA 94550; , , , , .; Center for Particle Astrophysics, University of California, Berkeley, CA 94720.), AB(Supercomputing Facility, Australian National University, Canberra, ACT 0200, Australia; .), AC(Lawrence Livermore National Laboratory, Livermore, CA 94550; , , , , .; Department of Physics, University of California, Davis, CA 95616.), AD(Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611, Australia; , , , .), AE(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Departments of Astronomy and Physics, University of Washington, Seattle, WA 98195; , , .), AF(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Department of Physics, University of California, Davis, CA 95616.; Department of Physics, University of Notre Dame, Notre Dame, IN 46556.), AG(Lawrence Livermore National Laboratory, Livermore, CA 94550; , , , , .; Center for Particle Astrophysics, University of California, Berkeley, CA 94720.), AH(Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611, Australia; , , , .), AI(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Department of Physics, University of California, San Diego, La Jolla, CA 92093; , , .), AJ(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Department of Physics, University of California, San Diego, La Jolla, CA 92093; , , .), AK(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Department of Physics, University of California, San Diego, La Jolla, CA 92093; , , .), AL(Lawrence Livermore National Laboratory, Livermore, CA 94550; , , , , .; Center for Particle Astrophysics, University of California, Berkeley, CA 94720.), AM(Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611, Australia; , , , .), AN(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Departments of Astronomy and Physics, University of Washington, Seattle, WA 98195; , , .; Department of Physics, University of California, Santa Barbara, CA 93106.), AO(European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748, Garching, Germany; .), AP(Mount Stromlo and Siding Spring Observatories, Australian National University, Weston, ACT 2611, Australia; , , , .), AQ(Center for Particle Astrophysics, University of California, Berkeley, CA 94720.; Departments of Astronomy and Physics, University of Washington, Seattle, WA 98195; , , .), AR(Department of Physics, University of Oxford, Oxford OX1 3RH, England, UK; .), AS(Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1; .)
%J The Astrophysical Journal
%V 486
%D 1997
%8 September 01, 1997
%P 697
%K Cosmology: Dark Matter; Galaxy: Halo; Cosmology: Gravitational
Lensing; Galaxies: Magellanic Clouds; Stars: Low-Mass; Brown Dwarfs;
Stars: White Dwarfs; Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1997ApJ...486..697A
%X The MACHO Project is a search for dark matter in the form of massive compact halo objects (MACHOs). Photometric monitoring of millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge is used to search for gravitational microlensing events caused by these otherwise invisible objects. Analysis of the first 2.1 yr of photometry of 8.5 million stars in the LMC reveals eight candidate microlensing events. This is substantially more than the number expected (~1.1) from lensing by known stellar populations. The timescales (t) of the events range from 34 to 145 days. We estimate the total microlensing optical depth toward the LMC from events with 2&lt;t̂&lt;200 days to be τ<SUP>200</SUP><SUB>2</SUB>=2.9<SUP>+1.4</SUP><SUB>-0.9</SUB>×10<SUP>-7</SUP> based upon our eight event sample. This exceeds the optical depth, τ<SUB>backgnd</SUB> = 0.5 × 10<SUP>-7</SUP>, expected from known stars, and the difference is to be compared with the optical depth predicted for a ``standard'' halo composed entirely of MACHOs: τ<SUB>halo</SUB> = 4.7 × 10<SUP>-7</SUP>. To compare with Galactic halo models, we perform likelihood analyses on the full eight-event sample and a six-event subsample (which allows for two events to be caused by a nonhalo ``background''). This gives a fairly model-independent estimate of the halo mass in MACHOs within 50 kpc of 2.0<SUP>+1.2</SUP><SUB>-0.7</SUB>×10<SUP>11</SUP> M<SUB>☉</SUB>, which is about half of the ``standard halo'' value. We also find a most probable MACHO mass of 0.5<SUP>+0.3</SUP><SUB>-0.2</SUB> M<SUB>☉</SUB>, although this value is strongly model dependent. In addition, the absence of short duration events places stringent upper limits on the contribution of low-mass MACHOs: objects from 10<SUP>-4</SUP> M<SUB>☉</SUB> to 0.03 M<SUB>☉</SUB> contribute &lt;~20% of the ``standard'' dark halo.
%R 10.1086/304535
%= eprint: arXiv:astro-ph/9606165
%@ 0004-637X


%0 Journal Article
%T A Binary Lensing Event Toward the LMC: Observations and Dark Matter Implications
%A Bennett, D. P.
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Becker, A.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Lehner, M. J.
%A Marshall, S. L.
%A Minniti, D.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rhie, S. H.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A Welch, D.
%+ AA(Supercomputing Facility, Australian National Univ. Canberra, ACT 0200, Australia), AB(Mount Stromlo and Siding Springs Obs., Australian National Univ. Weston, ACT 2611, Australia), AC(Mount Stromlo and Siding Springs Obs., Australian National Univ. Weston, ACT 2611, Australia), AD(Mount Stromlo and Siding Springs Obs., Australian National Univ. Weston, ACT 2611, Australia), AE(European Southern Observatory Garching bei München, Germany), AF(Mount Stromlo and Siding Springs Obs., Australian National Univ. Weston, ACT 2611, Australia), AG(Department of Physics, University of Oxford Oxford OX1 3RH, UK), AH(Departments of Physics and Astronomy, McMaster Univ. Hamilton, Ont., L8S 4M1, Canada)
%J Nuclear Physics B Proceedings Supplements, Vol. 51
%V 51
%D 1996
%8 November 01, 1996
%P 152
%K Astrophysics
%U https://ui.adsabs.harvard.edu/abs/1996NuPhS..51..152B
%X The MACHO collaboration has recently analyzed 2.1 years of photometric data for about 8.5 million stars in the Large Magellanic Cloud (LMC). This analysis has revealed 8 candidate microlensing events and a total microlensing optical depth of τ<SUB>meas</SUB> = 2.9<SUP>+1.4</SUP><SUB>-0.9</SUB> × 10<SUP>-7</SUP>. This significantly exceeds the number of events (1.1) and the microlensing optical depth predicted from known stellar populations: τ<SUB>back</SUB> = 5.4 × 10<SUP>-8</SUP>, but it is consistent with models in which about half of the standard dark halo mass is composed of Machos of mass ~ 0.4M<SUB>solar</SUB>. One of these 8 events appears to be a binary lensing event with a caustic crossing that is partially resolved, and the measured caustic crossing time allows us to estimate the distance to the lenses. Under the assumption that the source star is a single star and not a short period binary, we show that the lensing objects are very likely to reside in the LMC. However, if we assume that the optical depth for LMC-LMC lensing is large enough to account for our entire lensing signal, then the binary event does not appear to be consistent with lensing of a single LMC source star by a binary residing in the LMC. Thus, while the binary lens may indeed reside in the LMC, there is no indication that most of the lenses reside in the LMC.
%R 10.1016/S0920-5632(96)00497-5
%= eprint: arXiv:astro-ph/9606012
%@ 0920-5632


%0 Journal Article
%T The MACHO Project Constraints on Low Mass Machos in the Galactic Halo
%A Lehner, M. J.
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Becker, A.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Marshall, S. L.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%+ AA(Supercomputing Facility, Australian National University Canberra, ACT 0200, Australia), AB(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AC(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AD(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AE(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AF(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AG(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AH(Department of Physics, University of Oxford Oxford OX1 3RH, UK)
%J Nuclear Physics B Proceedings Supplements, Vol. 51
%V 51
%D 1996
%8 November 01, 1996
%P 141
%U https://ui.adsabs.harvard.edu/abs/1996NuPhS..51..141L
%X The MACHO project has been monitoring about ten million stars in the Large Magellanic Cloud in the search for gravitational microlensing events caused by massive compact halo objects (Machos) in the halo of the Milky Way. The standard analysis for well sampled, long duration microlensing is sensitive to objects with masses 10<SUP>-5</SUP> &lt;~ m &lt;~ 1M<SUB>solar</SUB>. However, a different analysis method sensitive to short duration events extends the sensitivity of the experiment to lower masses. Combining the results of the analyses of the first two years of data from the LMC shows that Machos with masses in the range 2.5 × 10<SUP>-7</SUP> &lt; m &lt; 8.1 × 10<SUP>-2</SUP> M<SUB>solar</SUB> cannot make up the entire mass of a standard spherical dark halo.
%R 10.1016/S0920-5632(96)00495-1
%@ 0920-5632


%0 Journal Article
%T The MACHO Project 2nd Year LMC Microlensing Results and Dark Matter Implications
%A Pratt, M. R.
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Becker, A. C.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Lehner, M. J.
%A Marshall, S. L.
%A Peterson, B. A.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A Welch, D. L.
%+ AA(Supercomputing Facility, Australian National University Canberra, ACT 0200, Australia), AB(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AC(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AD(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AE(European Southern Observatory, Karl-Schwarschild Str. 2 D-85748, Garching bei München, Germany), AF(Mount Stromlo and Siding Springs Observatoires, Australian National University Weston, ACT 2611, Australia), AG(Department of Physics, University of Oxford Oxford OX1 3RH, UK), AH(McMaster University Hamilton Ontario L8S 4M1, Canada)
%J Nuclear Physics B Proceedings Supplements, Vol. 51
%V 51
%D 1996
%8 November 01, 1996
%P 131
%K Astrophysics
%U https://ui.adsabs.harvard.edu/abs/1996NuPhS..51..131P
%X The MACHO Project is searching for galactic dark matter in the form of massive compact halo objects (Machos). Millions of stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and Galactic bulge are photometrically monitored in an attempt to detect rare gravitational microlensing events caused by otherwise invisible Machos. Analysis of two years of photometry on 8.5 million stars in the LMC reveals 8 candidate microlensing events, far more than the ~ 1 event expected from lensing by low-mass stars in known galactic populations. From these eight events we estimate the optical depth towards the LMC from events with 2 &lt; t &lt; 200 days to be τ<SUP>200</SUP><SUB>2</SUB> ~ 2.9<SUP>+1.4</SUP><SUB>-0.9</SUB> × 10<SUP>-7</SUP>. This exceeds the optical depth of 0.5 × 10<SUP>-7</SUP> expected from known stars and is to be compared with an optical depth of 4.7 × 10<SUP>-7</SUP> predicted for a ``standard'' halo composed entirely of Machos. The total mass in this lensing population is ~ 2<SUP>+1.2</SUP><SUB>-0.7</SUB> × 10<SUP>11</SUP> M<SUB>solar</SUB> (within 50 kpc from the Galactic center). Event timescales yield a most probable Macho mass of 0.5<SUP>+0.3</SUP><SUB>-0.2</SUB> M<SUB>solar</SUB>, although this value is quite model dependent.
%R 10.1016/S0920-5632(96)00494-X
%= eprint: arXiv:astro-ph/9606134
%@ 0920-5632


%0 Journal Article
%T The MACHO Project: Limits on Planetary Mass Dark Matter in the Galactic Halo from Gravitational Microlensing
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Becker, A. C.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Lehner, M. J.
%A Marshall, S. L.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A MACHO Collaboration
%J The Astrophysical Journal
%V 471
%D 1996
%8 November 01, 1996
%P 774
%K COSMOLOGY: DARK MATTER; GALAXY: HALO; GALAXY: STELLAR CONTENT;
COSMOLOGY: GRAVITATIONAL LENSING; STARS: LOW-MASS; BROWN DWARFS;
Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1996ApJ...471..774A
%X The MACHO project has been monitoring about 10 million stars in the Large Magellanic Cloud (LMC) in the search for gravitational microlensing events caused by massive compact halo objects (MACH Os) in the halo of the Milky Way. In our standard analysis, we have searched this data set for well-sampled, long-duration microlensing light curves, detected several microlensing events consistent with MACHOs in the 0.1 M<SUB>sun</SUB> ≤ m ≤ 1.0 M<SUB>sun</SUB> mass range, and set limits on the abundance of objects with masses 10<SUP>-5</SUP> M<SUB>sun</SUB> ≤ m ≤ 10<SUP>-1</SUP> M<SUB>sun</SUB>. In this paper, we present a different type of analysis involving the search for very short timescale brightenings of stars, which is used to set strong limits on the abundance of lower mass MACHOs. Our analysis of the first 2 years of data toward the LMC indicates that MACHOs with masses in the range 2.5 x 10<SUP>-7</SUP> M<SUB>sun</SUB> &lt; m &lt; 5.2 x 10<SUP>-4</SUP> M<SUB>sun</SUB> cannot make up the entire mass of a standard spherical dark halo. Combining these results with those from the standard analysis, we find that the halo dark matter cannot be comprised of objects with masses 2.5 x 10<SUP>-7</SUP> M<SUB>sun</SUB> &lt; m &lt; 8.1 x 10<SUP>-2</SUP> M<SUB>sun</SUB>.
%R 10.1086/178005
%= eprint: arXiv:astro-ph/9604176
%@ 0004-637X


%0 Journal Article
%T The MACHO Project First-Year Large Magellanic Cloud Results: The Microlensing Rate and the Nature of the Galactic Dark Halo
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J. A.
%A Lehner, M. J.
%A Marshall, S. L.
%A Park, H. -S.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%J The Astrophysical Journal
%V 461
%D 1996
%8 April 01, 1996
%P 84
%K GALAXY: HALO; COSMOLOGY: DARK MATTER; COSMOLOGY: GRAVITATIONAL
LENSING; GALAXIES: MAGELLANIC CLOUDS; STARS: LOW-MASS; BROWN DWARFS;
Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1996ApJ...461...84A
%X Since July 1992, the MACHO project has been carrying out long-term photometric monitoring of over 20 million stars in the Magellanic Clouds and Galactic bulge. Our aim is to search for the very rare gravitational microlensing events predicted if the dark halo of our Galaxy is comprised of massive compact halo objects (hereafter MACHOs). We have now analyzed most of the first year's LMC data, comprising 9.5 million light curves of stars with an average of 235 observations each. Automated selection procedures applied to this sample show three events consistent with microlensing; the first detected is very striking (Alcock and coworkers), and two are of modest amplitude. We have evaluated our experimental detection efficiency using a range of detailed Monte Carlo simulations, including the addition of artificial stars to real data frames. Using a "standard" halo density profile, we find that a halo comprised entirely of MACHOs in the mass range 3 x 10^-4^ to 0.06 M_sun_ would predict more than 15 detected events in this data set, and objects around 3 x 10^-3^ M_sun_ would predict 25 events; thus a standard spherical halo cannot be dominated by objects in this mass range. Assuming all three events are microlensing by halo objects, and fitting a naive spherical halo model to our data yields a MACHO halo fraction f= 0.19_= 0.10_^+0.16^, a total mass in MACHOs (inside 50 kpc) of 7.6_-4_^+6^ x 10^10^ M_sun_, and a microlensing optical depth 8.8_-5_^+7^ x 10^-8^(68% confidence level). Should only one of these events be microlensing, this could be explained in terms of previously known populations. We have explored a wide range of halo models and find that, while our constraints on the MACHO fraction are quite model dependent, constraints on the total mass in MACHOs within 50 kpc are quite secure. Future observations from this and other similar projects, and accurate measurements of the Galactic mass out to large radii, should combine to give much improved constraints on the MACHO fraction of the halo.
%R 10.1086/177039
%= eprint: arXiv:astro-ph/9506113
%@ 0004-637X


%0 Journal Article
%T Low noise voltage and charge preamplifiers for phonon and ionization detectors at very low temperature
%A Yvon, D.
%A Cummings, A.
%A Stockwell, W.
%A Barnes, P.
%A Stanton, C.
%A Sadoulet, B.
%A Shutt, T.
%A Stubbs, C.
%+ AA(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AB(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AC(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AD(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AE(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AF(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AG(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.), AH(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94720, USA; Current address: CEA, DSM/DAPNIA/Service de Physique des Particules, CE-SACLAY, F-91191 Gif-sur-Yvette Cedex, France.; Current address: Departments of Astronomy &amp; Physics; FM 20; University of Washington; Seattle, WA, USA.)
%J Nuclear Instruments and Methods in Physics Research A
%V 368
%D 1996
%8 February 01, 1996
%P 778
%U https://ui.adsabs.harvard.edu/abs/1996NIMPA.368..778Y
%X We have developed voltage and charge sensitive FET preamplifiers which feature ultra low noise, convenience and flexibility for phonon and ionization detectors operated at 20 mK. With an NJ132L J-FET, the white noise of the voltage amplifier is 1.1 nV/√Hz at room temperature and 0.9 nV/√Hz when the FET is cooled to ≈120 K; the {1}/{f} knee is below 100 Hz. The power dissipation of the FET, about 7 mW in our application, allows it to be used in a 4 K environment. With the same cooled FET, the charge amplifier has shown a noise of 120 e <SUP>-</SUP> rms with a total input capacitance of 45 pF.
%R 10.1016/0168-9002(95)00665-6
%@ 0168-9002


%0 Book Section
%T Optical Variability of the LMC Supersoft Source RX J0513.9-6951
%A Southwell, K. A.
%A Livio, M.
%A Charles, P. A.
%A Sutherland, W.
%A Alcock, C.
%A Allsman, R. A.
%A Alves, D.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J.
%A Lehner, M. J.
%A Marshall, S. L.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Welch, D. L.
%+ AA(Dept. of Astrophysics), AB(Space Telescope Science Inst.), AC(Dept. of Astrophysics), AD(Dept. of Astrophysics), AE(Lawrence Livermore National Laboratory; Center for Particle Astrophysics, University of California), AF(Supercomputing Facility, Australian Nat. Univ.), AG(Lawrence Livermore National Laboratory), AH(Lawrence Livermore National Laboratory, Mt. Stromlo and Siding Spring Observatories), AI(Lawrence Livermore National Laboratory; Center for Particle Astrophysics, University of California), AJ(Lawrence Livermore National Laboratory; Center for Particle Astrophysics, University of California), AK(Mt. Stromlo and Siding Spring Observatories), AL(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AM(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AN(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AO(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AP(Mt. Stromlo and Siding Spring Observatories), AQ(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AR(Mt. Stromlo and Siding Spring Observatories), AS(Mt. Stromlo and Siding Spring Observatories), AT(Center for Particle Astrophysics, University of California; Department of Physics, University of California), AU(Dept. of Physics and Astronomy, Mc Master University)
%J Supersoft X-Ray Sources
%V 472
%D 1996
%8 January 01, 1996
%P 165
%U https://ui.adsabs.harvard.edu/abs/1996LNP...472..165S
%X We present optical spectroscopy and photometry of the LMC supersoft source (SSS) RX J0513.9-6951. Through the exceptional monitoring capabilities of the MACHO project, we show the optical history of this object for a≈3 year period. Recurring low states, in which the optical brightness drops by up to a magnitude, are observed at quasi-regular intervals. Analysis of the high state data reveals a small modulation with a semi-amplitude of ≈0.02 magnitudes at P=0<SUP>d</SUP>.76278±0<SUP>d</SUP>.00005. By considering all the available data, including optical photometry, spectroscopy and X-ray observations, we suggest a theoretical model to explain the fundamental variations exhibited by this source.
%R 10.1007/BFb0102261
%@ 0075-8450


%0 Journal Article
%T Theory of Exploring the Dark Halo with Microlensing. I. Power-Law Models
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Evans, N. W.
%A Freeman, K. C.
%A Griest, K.
%A Jijina, J.
%A Lehner, M.
%A Marshall, S. L.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A MACHO Collaboration
%J The Astrophysical Journal
%V 449
%D 1995
%8 August 01, 1995
%P 28
%K COSMOLOGY: GRAVITATIONAL LENSING; COSMOLOGY: DARK MATTER; GALAXIES:
HALOS; GALAXY: STRUCTURE; Astrophysics; High Energy Physics -
Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1995ApJ...449...28A
%X If microlensing of stars by dark matter has been detected, then the way is open for the development of new methods in galactic astronomy. This series of papers investigates what microlensing can teach us about the structure and shape of the dark halo. In this paper we present formulae for the microlensing rate, optical depth, and event duration distributions for a simple set of axisymmetric disk-halo models. The halos are based on the "power-law models" of Evans which have simple velocity distributions. <P />Using these models, we show that there is a large uncertainty in the predicted microlensing rate because of uncertainty in the halo parameters. For example, models which reproduce the measured galactic observables to within their errors still differ in microlensing rate toward the Magellanic Clouds by more than a factor of 10. We find that while the more easily computed optical depth correlates well with microlensing rate, the ratio of optical depth to rate can vary by a factor of 2 (or greater if the disk is maximal). Comparison of microlensing rates toward the Large and Small Magellanic Clouds (LMC and SMC) and M31 can be used to aid determinations of the halo flattening and rotation curve slope. For example, the ratio of microlensing rates toward the LMC and SMC is ˜0.7-0.8 for E0 halos and ˜1.0-1.2 for E7 halos. Once the flattening has been established, the ratio of microlensing rates toward M3 1 and the LMC may help to distinguish between models with rising, flat, or falling rotation curves. Comparison of rates along LMC and galactic bulge lines of sight gives useful information on the halo core radius, although this may not be so easy to extract in practice. Maximal disk models provide substantially smaller halo optical depths, shorter event durations, and even larger model uncertainties.
%R 10.1086/176028
%= eprint: arXiv:astro-ph/9411019
%@ 0004-637X


%0 Conference Proceedings
%T Looking for dark matter via gravitational microlensing: A report from the MACHO collaboration
%A Pratt, M. R.
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Chan, S.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Marshall, S. L.
%A Peterson, B. A.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%+ AA(Center for Particle Astrophysics, University of California, Berkeley, California 94720University of California, Santa Barbara, California 93106), AB(Lawrence Livermore National Laboratory, Livermore, California 94550; Center for Particle Astrophysics, University of California, Berkeley, California 94720), AC(Lawrence Livermore National Laboratory, Livermore, California 94550), AD(Lawrence Livermore National Laboratory, Livermore, California 94550; Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AE(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Lawrence Livermore National Laboratory, Livermore, California 94550), AF(Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AG(Lawrence Livermore National Laboratory, Livermore, California 94550), AH(Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AI(Center for Particle Astrophysics, University of California, Berkeley, California 94720; University of California, San Diego, California 92039), AJ(Center for Particle Astrophysics, University of California, Berkeley, California 94720; University of California, Santa Barbara, California 93106), AL(Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AM(Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AN(Mount Stromlo and Siding Springs Observatoires, Australian National University, Weston, ACT 2611, Australia), AO(Center for Particle Astrophysics, University of California, Berkeley, California 94720; University of Washington, Seattle Washington 98195)
%J CAM-94 Physics meeting
%V 342
%D 1995
%8 August 01, 1995
%P 106
%K 95.35.+d; 98.62.Sb; Dark matter; Gravitational lenses and luminous
arcs
%U https://ui.adsabs.harvard.edu/abs/1995AIPC..342..106P
%X There is convincing evidence that the mass of ordinary galaxies, like our own, is much greater than that measured in the form of stars, gas, and dust. If this dark matter is in the form of compact objects it can be detected via gravitational microlensing of background stars. The MACHO project is in its second year of a time resolved photometric survey of the Magellanic Clouds and galactic bulge to search for the rare microlensing signature of compact objects in the halo and disk of our galaxy. We are using a dedicated 1.3-m telescope at Mt. Stromlo Observatory and a dual focal plane CCD mosaic camera with a 0.5 square degree field to image up to 10 million stars per night simultaneously in two passbands. As of October 1994, 26,000 images have been taken with this system. A preliminary analysis of more than 8 million stars in the LMC for one year has yielded three stars which undergo time-symmetric achromatic photometric excursions consistent with gravitational microlensing. In a similar analysis of ~10 million stars in the galactic bulge we have also found more than 40 likely microlensing candidates, several of which reach peak amplifications of greater than ten. The relatively high rate toward the bulge is consistent with a ``maximal'' disk that accounts for most of the galactic mass interior to the solar radius or microlensing by a galactic bar.
%R 10.1063/1.48815
%@ 0094-243X


%0 Conference Proceedings
%T Recent developments in gravitational microlensing and the latest MACHO results: Microlensing towards the galactic bulge
%A Bennett, D. P.
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Marshall, S. L.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%+ AA(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Lawrence Livermore National Laboratory, Livermore, California 94550), AB(Lawrence Livermore National Laboratory, Livermore, California 94550; Center for Particle Astrophysics, University of California, Berkeley, California 94720), AC(Lawrence Livermore National Laboratory, Livermore, California 94550), AD(Lawrence Livermore National Laboratory, Livermore, California 94550), AE(Lawrence Livermore National Laboratory, Livermore, California 94550; Center for Particle Astrophysics, University of California, Berkeley, California 94720), AF(Mt. Stromlo and Siding Spring Observatoires, Australian National University, Weston, ACT 2611, Australia), AG(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Department of Physics, University of California, San Diego, California 92039), AH(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Department of Physics, University of California, Santa Barbara, California 93106), AI(Center for Particle Astrophysics, University of California, Berkeley, California 94720), AJ(Mt. Stromlo and Siding Spring Observatoires, Australian National University, Weston, ACT 2611, Australia), AK(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Department of Physics, University of California, Santa Barbara, California 93106), AL(Mt. Stromlo and Siding Spring Observatoires, Australian National University, Weston, ACT 2611, Australia), AM(Mt. Stromlo and Siding Spring Observatoires, Australian National University, Weston, ACT 2611, Australia), AN(Mt. Stromlo and Siding Spring Observatoires, Australian National University, Weston, ACT 2611, Australia), AO(Center for Particle Astrophysics, University of California, Berkeley, California 94720; Department of Astronomy, University of Washington, Seattle, Washington 98195)
%J Dark Matter
%V 336
%D 1995
%8 July 01, 1995
%P 77
%K 98.62.Sb; Gravitational lenses and luminous arcs; Astrophysics
%U https://ui.adsabs.harvard.edu/abs/1995AIPC..336...77B
%X We review recent gravitational microlensing results from the EROS, MACHO, and OGLE collaborations, and present some details of the very latest MACHO results toward the Galactic Bulge, The MACHO collaboration has now discovered in excess of 40 microlensing events toward the Galactic Bulge during the 1993 observing season. A preliminary analysis of this data suggests a much higher microlensing optical depth than predicted by standard galactic models suggesting that these models will have to be revised. This may have important implications for the structure of the Galaxy and its dark halo. Also shown are MACHO data of the first microlensing event ever detected substantially before peak amplification, the first detection of parallax effects in a microlensing event, and the first caustic crossing to be resolved in a microlensing event.
%R 10.1063/1.48390
%= eprint: arXiv:astro-ph/9411114
%@ 0094-243X


%0 Electronic Article
%T MACHO COLLABORATION SEARCH FOR BARYONIC DARK MATTER VIA GRAVITATIONAL MICROLENSING
%A Griest, K.
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Guern, J.
%A Lehner, M.
%A Marshall, S. L.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%A Welch, D.
%J arXiv e-prints
%D 1995
%8 June 01, 1995
%P astro-ph/9506016
%K Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1995astro.ph..6016G
%X Results are presented from the MACHO collaboration gravitational microlensing search. The experiment and the nearly 50 microlensing events that have been detected are described. Limits on the baryonic content of the halo are given, as are estimates of the Macho contribution to the dark halo. Optical depths toward the bulge, and several unusual events such as a binary lens and a parallax event are discussed. Possible interpretations of these results are also discussed.
%= eprint: arXiv:astro-ph/9506016


%0 Journal Article
%T Experimental Limits on the Dark Matter Halo of the Galaxy from Gravitational Microlensing
%A Alcock, C.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Guern, J. A.
%A Lehner, M. J.
%A Marshall, S. L.
%A Park, H. -S.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%+ AA(Lawrence Livermore National Laboratory, Livermore, California 94550), AB(Lawrence Livermore National Laboratory, Livermore, California 94550), AC(Lawrence Livermore National Laboratory, Livermore, California 94550), AD(Lawrence Livermore National Laboratory, Livermore, California 94550), AE(Lawrence Livermore National Laboratory, Livermore, California 94550), AF(Lawrence Livermore National Laboratory, Livermore, California 94550), AG(Lawrence Livermore National Laboratory, Livermore, California 94550), AH(Lawrence Livermore National Laboratory, Livermore, California 94550), AI(Lawrence Livermore National Laboratory, Livermore, California 94550), AJ(Lawrence Livermore National Laboratory, Livermore, California 94550), AK(Lawrence Livermore National Laboratory, Livermore, California 94550), AL(Lawrence Livermore National Laboratory, Livermore, California 94550), AM(Lawrence Livermore National Laboratory, Livermore, California 94550), AN(Lawrence Livermore National Laboratory, Livermore, California 94550), AO(Lawrence Livermore National Laboratory, Livermore, California 94550), AP(Lawrence Livermore National Laboratory, Livermore, California 94550), AQ(Lawrence Livermore National Laboratory, Livermore, California 94550), AR(Lawrence Livermore National Laboratory, Livermore, California 94550)
%J Physical Review Letters
%V 74
%D 1995
%8 April 01, 1995
%P 2867
%K Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1995PhRvL..74.2867A
%X We monitored 8.6×10<SUP>6</SUP> stars in the Large Magellanic Cloud for 1.1 years and have found three events consistent with gravitational microlensing. We place strong constraints on Galactic halo lensing objects in the mass range 10<SUP>-4</SUP>M<SUB>solar</SUB> to 10<SUP>-1</SUP>M<SUB>solar</SUB>. Three events are fewer than expected for a standard spherical halo of objects in this mass range, but appear to exceed the number expected from known Galactic populations. Fitting a naive spherical halo model to our data yields a MACHO fraction f of massive compact halo objects (MACHOs), f = 0.19<SUP>+0.16</SUP><SUB>-0.10</SUB>, a total MACHO mass (inside 50 kpc) of 7.6<SUP>+6</SUP><SUB>-4</SUB>×10<SUP>10</SUP>M<SUB>solar</SUB>, and a microlensing optical depth 8.8<SUP>+7</SUP><SUB>-5</SUB>×10<SUP>-8</SUP> (68% C.L.).
%R 10.1103/PhysRevLett.74.2867
%= eprint: arXiv:astro-ph/9501091
%@ 0031-9007


%0 Conference Proceedings
%T 8-megapixel thermoelectrically cooled CCD imaging system
%A Diercks, Alan H.
%A Angione, John
%A Stubbs, Christopher W.
%A Cook, Kem H.
%A Bowell, Edward
%A Koehn, Bruce W.
%A Nye, Ralph A.
%A Dodgen, Dave
%+ AA(University of Washington), AB(Lawrence Livermore National Lab.), AC(Lowell Observatory), AD(Dodgen Optical Co.)
%J Cameras and Systems for Electronic Photography and Scientific Imaging
%V 2416
%D 1995
%8 March 01, 1995
%P 58
%U https://ui.adsabs.harvard.edu/abs/1995SPIE.2416...58D
%X We are developing an astronomical imaging system which employs a thermoelectrically cooled focal plane consisting of two 'edge-buttable' Loral 2048 X 2048 pixel CCDs. To allow strip scanning, the columns of the CCDs are mutually aligned on a custom Kovar mount. The clocking and bias voltage levels for each CCD are independently adjustable, but both CCDs are operated synchronously. Each chip is read out from one output and measured at 14 bits with commercially available A/D converters at a rate of 250 kpixels/s, permitting scanning across the sky at up to 1000 deg<SUP>2</SUP>/hr (about twenty times faster than the equatorial sidereal rate) to a limiting magnitude (S/N equals 3) near V equals 19. The instrument will be used as part of the Lowell Observatory Near-Earth-Object Search (LONEOS) using a 57-cm Schmidt telescope at Lowell Observatory in Flagstaff, Arizona.
%R 10.1117/12.204839
%@ 0277-786X


%0 Journal Article
%T Gravitational Microlensing Results from MACHO
%A Sutherland, W.
%A Alcock, C.
%A Allsman, R.
%A Axelrod, T.
%A Bennett, D.
%A Chan, S.
%A Cook, K.
%A Freeman, K.
%A Griest, K.
%A Marshall, S.
%A Perlmutter, S.
%A Peterson, B.
%A Pratt, M.
%A Quinn, P.
%A Rodgers, A.
%A Stubbs, C.
%+ AA(Mt. Stromlo &amp; Siding Spring Observatoires Canberra, ACT 2611, Australia), AB(Mt. Stromlo &amp; Siding Spring Observatoires Canberra, ACT 2611, Australia), AC(Mt. Stromlo &amp; Siding Spring Observatoires Canberra, ACT 2611, Australia), AD(Mt. Stromlo &amp; Siding Spring Observatoires Canberra, ACT 2611, Australia), AE(Mt. Stromlo &amp; Siding Spring Observatoires Canberra, ACT 2611, Australia)
%J Nuclear Physics B Proceedings Supplements
%V 38
%D 1995
%8 January 01, 1995
%P 379
%K Astrophysics
%U https://ui.adsabs.harvard.edu/abs/1995NuPhS..38..379S
%X We provide a status report on our search for dark matter in our Galaxy in the form of massive compact halo objects (MACHOs), using gravitational microlensing of background stars. This search uses a very large CCD camera on the dedicated 1.27m telescope at Mt.~Stromlo, Australia, and has been taking data for 2 years. At present, we have analysed data for 8 million stars in the Large Magellanic Cloud over 1 year, resulting in one strong candidate event and two lower-amplitude candidates. We have also analysed 5 million stars in the Galactic Bulge for 0.5 years, yielding approximately 27 microlensing events.
%R 10.1016/0920-5632(94)00772-N
%= eprint: arXiv:astro-ph/9409034
%@ 0920-5632


%0 Journal Article
%T Low noise front end electronics for dilution refrigerator experiments
%A Stockwell, W.
%A Yvon, D.
%A Aubourg, É.
%A Barnes, P. D.
%A Cummings, A.
%A da Silva, A.
%A Ellman, B.
%A Ross, R. R.
%A Sadoulet, B.
%A Shutt, T.
%A Smith, G.
%A Stubbs, C.
%A Wang, N.
%A White, S.
%A Young, B. A.
%+ AA(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AB(DAPNIA-SPP, CEN Saclay; Center for Particle Astrophysics, University of California at Berkeley), AC(DAPNIA-SPP, CEN Saclay; Center for Particle Astrophysics, University of California at Berkeley), AD(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AE(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AF(Department of Physics, UC Berkeley; Department of Physics, University of British Columbia), AG(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AH(Department of Physics, UC Berkeley; , Lawrence Berkeley Laboratory), AI(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AJ(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AK(Lawrence Berkeley Laboratory; Center for Particle Astrophysics, University of California at Berkeley), AL(Department of Physics, UC Santa Barbara; Center for Particle Astrophysics, University of California at Berkeley), AM(Physics Department, California Institute of Technology; Center for Particle Astrophysics, University of California at Berkeley), AN(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley), AO(Department of Physics, UC Berkeley; Center for Particle Astrophysics, University of California at Berkeley)
%J Journal of Low Temperature Physics
%V 93
%D 1993
%8 November 01, 1993
%P 755
%U https://ui.adsabs.harvard.edu/abs/1993JLTP...93..755S
%X We have developed low noise voltage and low noise charge sensitive preamplifiers for use in dilution refrigerator experiments. The amplifiers use a JFET at 140K as the front end. Each JEET dissipates about 7 mW on the 4K heat sink. The flat noise of the voltage amplifier is 0.9 nV/Hz<SUP>1/2</SUP>, with the 1/f knee below 100 Hz. The charge amplifier noise is 500 eV with a total input capacitance of approximately 90 pF.
%R 10.1007/BF00693508
%@ 1063-777X0022-2291


%0 Journal Article
%T Possible gravitational microlensing of a star in the Large Magellanic Cloud
%A Alcock, C.
%A Akerlof, C. W.
%A Allsman, R. A.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Chan, S.
%A Cook, K. H.
%A Freeman, K. C.
%A Griest, K.
%A Marshall, S. L.
%A Park, H. -S.
%A Perlmutter, S.
%A Peterson, B. A.
%A Pratt, M. R.
%A Quinn, P. J.
%A Rodgers, A. W.
%A Stubbs, C. W.
%A Sutherland, W.
%J Nature
%V 365
%D 1993
%8 October 01, 1993
%P 621
%K Astrophysics; General Relativity and Quantum Cosmology; High Energy
Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1993Natur.365..621A
%X There is now abundant evidence for the presence of large quantities of unseen matter surrounding normal galaxies, including our own<SUP>1,2</SUP>. The nature of this 'dark matter` is unknown, except that it cannot be made of normal stars, dust or gas, as they would be easily detected. Exotic particles such as axions, massive neutrinos or other weakly interacting massive particles (collectively known as WIMPs) have been proposed<SUP>3,4</SUP>, but have yet to be detected. A less exotic alternative is normal matter in the form of bodies with masses ranging from that of a large planet to a few solar masses. Such objects, known collectively as massive compact halo objects<SUP>5</SUP> (MACHOs), might be brown dwarfs or `jupiters' (bodies too small to produce their own energy by fusion), neutron stars, old white dwarfs or black holes. Paczynski<SUP>6</SUP> suggested that MACHOs might act as gravitational microlenses, temporarily amplifying the apparent brightness of background stars in nearby galaxies. We are conducting a microlensing experiment to determine whether the dark matter halo of our Galaxy is made up of MACHOs. Here we report a candidate for such a microlensing event, detected by monitoring the light curves of 1.8 million stars in the Large Magellanic Cloud for one year. The light curve shows no variation for most of the year of data taking, and an upward excursion lasting over 1 month, with a maximum increase of ~2 mag. The most probable lens mass, inferred from the duration of the candidate lensing event, is ~0.1 solar mass.
%R 10.1038/365621a0
%= eprint: arXiv:astro-ph/9309052
%@ 0028-0836


%0 Conference Proceedings
%T 32-megapixel dual-color CCD imaging system
%A Stubbs, Christopher W.
%A Marshall, Stuart
%A Cook, Kenneth H.
%A Hills, Robert F.
%A Noonan, Joseph
%A Akerlof, Carl W.
%A Alcock, Charles R.
%A Axelrod, Timothy S.
%A Bennett, D.
%A Dagley, K.
%A Freeman, K. C.
%A Griest, Kim
%A Park, Hye-Sook
%A Perlmutter, Saul
%A Peterson, Bruce A.
%A Quinn, Peter J.
%A Rodgers, A. W.
%A Sosin, C.
%A Sutherland, W. J.
%+ AA(University of California/Berkeley; University of California/Santa Barbara), AB(University of California/Berkeley and Lawrence Livermore National Lab.), AC(Lawrence Livermore National Lab.), AD(University of California/Berkeley), AE(Lawrence Livermore National Lab.), AF(University of California/Berkeley), AG(Mt. Stromlo and Siding Spring Observatoires), AH(University of California/Berkeley; University of California/San Diego), AI(Lawrence Livermore National Lab.), AJ(University of California/Berkeley), AK(Mt. Stromlo and Siding Spring Observatoires), AL(University of California/Berkeley)
%J Charge-Coupled Devices and Solid State Optical Sensors III
%V 1900
%D 1993
%8 July 01, 1993
%P 192
%U https://ui.adsabs.harvard.edu/abs/1993SPIE.1900..192S
%X We have developed an astronomical imaging system that incorporates a total of eight 2048 X 2048 pixel CCDs into two focal planes, to allow simultaneous imaging in two colors. Each focal plane comprises four 'edge-buttable' detector arrays, on custom Kovar mounts. The clocking and bias voltage levels for each CCD are independently adjustable, but all the CCDs are operated synchronously. The sixteen analog outputs (two per chip) are measured at 16 bits with commercially available correlated double sampling A/D converters. The resulting 74 MBytes of data per frame are transferred over fiber optic links into dual-ported VME memory. The total readout time is just over one minute. We obtain read noise ranging from 6.5 e<SUP>-</SUP> to 10 e<SUP>-</SUP> for the various channels when digitizing at 34 Kpixels/sec, with full well depths (MPP mode) of approximately 100,000 e<SUP>-</SUP> per 15 micrometers X 15 micrometers pixel. This instrument is currently being used in a search of gravitational microlensing from compact objects in our Galactic halo, using the newly refurbished 1.3 m telescope at the Mt. Stromlo Observatory, Australia.
%R 10.1117/12.148597
%@ 0277-786X


%0 Journal Article
%T A cryogenic detector with simultaneous phonon and ionization measurement for background rejection
%A Shutt, T.
%A Barnes, P. D.
%A Cummings, A.
%A DaSilva, A.
%A Ellman, B.
%A Emes, J.
%A Giraud-Heraud, Y.
%A Haller, E. E.
%A Lange, A. E.
%A Ross, R. R.
%A Sadoulet, B.
%A Smith, G.
%A Stubbs, C.
%A Stockwell, W.
%A Wang, N.
%A White, S.
%A Young, B. A.
%A Yvon, D.
%+ AA(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AB(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AC(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AD(Department of Physics, University of British Columbia, 6224 Agricultural Rd., Vancouver, BC V6T 1Z1, Canada), AE(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AF(Orme des Merisiers-SPEC, CEN Saclay, 91191 Gif-Sur-Yvette Cedex, France), AG(Laboratoire de Physique Corpusculaire, College de France, 75231 Paris, France), AH(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AI(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AJ(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AK(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AL(Orme des Merisiers-SPEC, CEN Saclay, 91191 Gif-Sur-Yvette Cedex, France), AM(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AN(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AO(Orme des Merisiers-SPEC, CEN Saclay, 91191 Gif-Sur-Yvette Cedex, France), AP(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AQ(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA), AR(Center for Particle Astrophysics, University of California at Berkeley, Berkeley, CA 94609, USA)
%J Nuclear Instruments and Methods in Physics Research A
%V 326
%D 1993
%8 March 01, 1993
%P 166
%U https://ui.adsabs.harvard.edu/abs/1993NIMPA.326..166S
%X We report on the performance of a 60 g Ge detector that measures both ionization and phonons at cryogenic (∼ 25 mK) temperatures. This simultaneous measurements is a powerful new tool in experiments where the primary signal is a nuclear recoil (e.g., WIMP dark matter) that must be distinguished from a background of photons or charged particles that produce electron recoils. We have measured nuclear recoils produced by neutrons from a <SUP>252</SUP>Cf source, and can distinguish them from photons at energies as low as 2 keV in the ionization measurement. An important effect that can limit the efficiency of the background rejection technique is incomplete charge collection. We have tested our detector at ionization drift fields as low as 5 mV/cm and find that the phonon energy measured for each event depends on the amount of charge collected. From this we deduce details about charge trapping mechanisms.
%R 10.1016/0168-9002(93)90347-K
%@ 0168-9002


%0 Journal Article
%T Experimental limits on any long range nongravitational interaction between dark matter and ordinary matter
%A Stubbs, Christopher W.
%+ AA(California Univ., Santa Barbara and Berkeley)
%J Physical Review Letters
%V 70
%D 1993
%8 January 01, 1993
%P 119
%K Dark Matter; Galactic Clusters; Galactic Rotation; Gravitational
Effects; Spiral Galaxies; Luminosity; Milky Way Galaxy; Universe;
Astrophysics; 04.90.+e; 04.80.+z; 95.30.Sf; 95.35.+d; Other topics in
general relativity and gravitation; Relativity and gravitation; Dark
matter
%U https://ui.adsabs.harvard.edu/abs/1993PhRvL..70..119S
%X Much of the mass of the Universe is thought to reside in some as yet unidentified dark matter. This view is based on the analysis of trajectories of luminous ``tracers'' that map out the local potential, assuming that gravity is the only long ranged interaction between ordinary and dark matter. This assumption should be tested experimentally if possible. Laboratory tests of the weak equivalence principle can constrain (at an interesting level) any exotic coupling between ordinary and dark matter when analyzed as a test of the uniformity of free fall towards the center of the Galaxy.
%R 10.1103/PhysRevLett.70.119
%@ 0031-9007


%0 Conference Proceedings
%T The First Data from the MACHO Experiment
%A Bennett, David P.
%A Akerlof, C.
%A Alcock, C.
%A Allsman, R.
%A Axelrod, T.
%A Cook, K. H.
%A Freeman, K.
%A Griest, K.
%A Marshall, S.
%A Park, H. -S.
%A Perlmutter, S.
%A Peterson, B.
%A Quinn, P.
%A Rodgers, A.
%A Stubbs, C. W.
%A Sutherland, W.
%J Texas/PASCOS '92: Relativistic Astrophysics and Particle Cosmology
%V 688
%D 1993
%8 January 01, 1993
%P 612
%K Astrophysics; High Energy Physics - Phenomenology
%U https://ui.adsabs.harvard.edu/abs/1993NYASA.688..612B
%X MAssive Compact Halo Objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Paczynski noted that objects (dubbed MACHOs) with masses in the range $10^{-6}M_\odot &lt; M \simlt 100 M_\odot$. can be detected via gravitational microlensing of stars in the Magellanic Clouds with the caveat that only about one in $10^6$ stars will be lensed at any given time. Our group has recently begun a search for microlensing using a refurbished 1.27 meter telescope at the Mount Stromlo Observatory in Australia. Since the summer of 1992, we have been imaging up to $10^7$ stars a night in the Large Magellanic Cloud using our large format two-color $3.4\times 10^7$ pixel CCD camera. Here I report on our first results based on an analysis of $\sim 10^6$ of these stars. Although this is not enough data to make definitive statements about the nature of the dark matter, we are able to conclude that the rate of variable star background events is not larger than the expected MACHO signal.
%R 10.1111/j.1749-6632.1993.tb43945.x
%= eprint: arXiv:astro-ph/9304014
%@ 0077-8923


%0 Journal Article
%T Simultaneous high resolution meausurement of phonons and ionization created by particle interactions in a 60 g germanium crystal at 25 mK
%A Shutt, T.
%A Wang, N.
%A Ellman, B.
%A Giraud-Heraud, Y.
%A Stubbs, C.
%A Barnes, P. D., Jr.
%A Cummings, A.
%A da Silva, A.
%A Emes, J.
%A Haller, E. E.
%+ AA(California Univ., Berkeley), AB(California Univ., Berkeley; CEA, Centre d'Etudes Nucleaires de Saclay, Gif-sur-Yvette, France), AC(California Univ., Berkeley), AD(California Univ., Berkeley; College de France, Paris), AE(California Univ., Berkeley; California Univ., Santa Barbara), AF(California Univ., Berkeley), AG(California Univ., Berkeley), AH(California Univ., Berkeley; British Columbia Univ., Vancouver, Canada), AI(California Univ., Berkeley; Lawrence Berkeley Lab., Berkeley), AJ(California Univ., Berkeley; Lawrence Berkeley Lab., Berkeley)
%J Physical Review Letters
%V 69
%D 1992
%8 December 01, 1992
%P 3531
%K Doped Crystals; Electron Phonon Interactions; Germanium; Particle
Interactions; Semiconductors (Materials); High Resolution; Particle
Energy; Trapped Particles; Nuclear and High-Energy Physics; 63.20.-e;
29.90.+r; 72.20.Jv; Phonons in crystal lattices; Other topics in
elementary-particle and nuclear physics experimental methods and
instrumentation; Charge carriers: generation recombination lifetime and
trapping
%U https://ui.adsabs.harvard.edu/abs/1992PhRvL..69.3531S
%X We demonstrate simultaneous high energy resolution (rms~=800 eV) measurements of ionization and phonons created by particle interactions in a semiconductor crystal of macroscopic size (60 g germanium) at 25 mK. We present first studies of charge collection at biases below 1 V/cm, and find that, contrary to commonly held opinion, the full recoil energy of particle interactions is recovered as phonons when charge trapping is negligible. We also report an unanticipated correlation between charge collection and phonon energy at very low bias, and discuss this effect in terms of charge trapping.
%R 10.1103/PhysRevLett.69.3531
%@ 0031-9007


%0 Journal Article
%T Measurement of ionization and phonon production by nuclear recoils in a 60 g crystal of germanium at 25 mK
%A Shutt, T.
%A Ellman, B.
%A Barnes, P. D., Jr.
%A Cummings, A.
%A da Silva, A.
%A Emes, J.
%A Giraud-Héraud, Y.
%A Haller, E. E.
%A Lange, A. E.
%A Ross, R. R.
%A Rich, J.
%A Sadoulet, B.
%A Smith, G.
%A Stockwell, W.
%A Stubbs, C.
%A et al.
%+ AA(California Univ., Berkeley), AB(California Univ., Berkeley), AC(California Univ., Berkeley), AD(California Univ., Berkeley), AE(California Univ., Berkeley; British Columbia Univ., Vancouver, Canada), AF(California Univ; Lawrence Berkeley Lab., Berkeley), AG(California Univ., Berkeley; College de France, Paris), AH(California Univ; Lawrence Berkeley Lab., Berkeley), AI(California Univ., Berkeley), AJ(California Univ; Lawrence Berkeley Lab., Berkeley)
%J Physical Review Letters
%V 69
%D 1992
%8 December 01, 1992
%P 3425
%K Dark Matter; Electron Phonon Interactions; Germanium; Metal Crystals;
Weak Energy Interactions; Compton Effect; Ionization Coefficients;
Nuclear and High-Energy Physics; 29.40.Wk; 14.80.Pb; 61.80.Mk; 63.20.-e;
Solid-state detectors; Phonons in crystal lattices
%U https://ui.adsabs.harvard.edu/abs/1992PhRvL..69.3425S
%X We report on the first measurement of the absolute phonon energy and the amount of ionization produced by the recoil of nuclei and electrons in a 60 g germanium crystal at a temperature of about 25 mK. We find good agreement between our results and previous measurements of ionization yield from nuclear recoils in germanium. Our device achieves 10:1 discrimination between neutrons and photons in the few keV energy range, demonstrating the feasibility of this technique for large reductions of background in searches for direct interactions of weakly interacting massive particle dark matter.
%R 10.1103/PhysRevLett.69.3425
%@ 0031-9007


%0 Journal Article
%T Simultaneous measurement of thermal and ionization signals in a 60 g cryogenic germanium detector
%A Barnes, P. D.
%A da Silva, A.
%A Ellman, B.
%A Emes, J.
%A Haller, E. E.
%A Lange, A. E.
%A Ing, K.
%A Ross, R. R.
%A Sadoulet, B.
%A Shutt, T.
%A Smith, G.
%A Stubbs, C.
%A Wang, N.
%A White, S.
%A Yvon, D.
%J IEEE Transactions on Nuclear Science
%V 39
%D 1992
%8 October 01, 1992
%P 1237
%U https://ui.adsabs.harvard.edu/abs/1992ITNS...39.1237B
%R 10.1109/23.173183
%@ 0018-9499


%0 Journal Article
%T Hydration at the membrane protein-lipid interface
%A Ho, C.
%A Stubbs, C.
%J Biophysical Journal
%V 63
%D 1992
%8 October 01, 1992
%P 897
%U https://ui.adsabs.harvard.edu/abs/1992BpJ....63..897H
%R 10.1016/S0006-3495(92)81671-5
%@ 0006-3495


%0 Book Section
%T The Search for Massive Compact Halo Objects
%A Alcock, C.
%A Axelrod, T. S.
%A Bennett, D. P.
%A Cook, K. H.
%A Park, H. -S.
%A Griest, K.
%A Perlmutter, S.
%A Stubbs, C. W.
%A Freeman, K. C.
%A Peterson, B. A.
%A Quinn, P. J.
%A Rodgers, A. W.
%J Gravitational Lenses
%V 406
%D 1992
%8 January 01, 1992
%P 156
%U https://ui.adsabs.harvard.edu/abs/1992LNP...406..156A
%R 10.1007/3-540-55797-0_95
%@ 0075-8450


%0 Conference Proceedings
%T Detecting halo weakly interacting massive particles with a cryogenic phonon detector
%A Wang, N.
%A Barnes, P. D.
%A Cummings, A.
%A Emes, J.
%A Giraud-Héraud, Y.
%A Haller, E. E.
%A Lange, A.
%A Ross, R.
%A Sadoulet, B.
%A Shutt, T.
%A Stubbs, C.
%+ AA(California Univ; Lawrence Berkeley Lab., Berkeley), AB(California Univ; Lawrence Berkeley Lab., Berkeley), AC(California Univ; Lawrence Berkeley Lab., Berkeley), AD(California Univ; Lawrence Berkeley Lab., Berkeley), AE(College de France, Paris), AF(California Univ; Lawrence Berkeley Lab., Berkeley), AG(California Univ; Lawrence Berkeley Lab., Berkeley), AH(California Univ; Lawrence Berkeley Lab., Berkeley), AI(California Univ; Lawrence Berkeley Lab., Berkeley), AJ(California Univ; Lawrence Berkeley Lab., Berkeley)
%J After the first three minutes
%V 222
%D 1991
%8 April 01, 1991
%P 471
%K Galactic Halos; Particle Mass; Phonons; Radiation Detectors; Weak
Interactions (Field Theory); Astronomical Spectroscopy; Cryogenic
Equipment; Dark Matter; Astrophysics; 98.60.Pr; 95.55.Wk; 98.80.Es;
Observational cosmology
%U https://ui.adsabs.harvard.edu/abs/1991AIPC..222..471W
%X If dark matter in the halo is made of weakly interacting massive particles (WIMPs), it may be detected with a cryogenic phonon detector. Such a detector must have low energy threshold, high energy resolution, and, more importantly, good background rejection capability. It has been proposed that a good background rejection ratio can be obtained by a simultaneous measurement of phonons and ionization. To test this experimentally, we have built a 60 g Ge detector and have measured simultaneous phonon and ionization signals, each with 4 keV energy resolution. We present a simple estimate of the rejection ratios, and WIMP event rates that may be achieved by such a detector.
%R 10.1063/1.40418
%@ 0094-243X


%0 Conference Proceedings
%T A search for massive compact halo objects in our galaxy
%A Bennett, D. P.
%A Alcock, C.
%A Axelrod, T.
%A Cook, K.
%A Park, H.
%A Griest, K.
%A Stubbs, C.
%A Freeman, K.
%A Peterson, B.
%A Quinn, P.
%A Rogers, A.
%+ AA(Lawrence Livermore National Lab., Livermore, CA), AB(Lawrence Livermore National Lab., Livermore, CA), AC(Lawrence Livermore National Lab., Livermore, CA), AD(Lawrence Livermore National Lab., Livermore, CA), AE(Lawrence Livermore National Lab., Livermore, CA), AF(California Univ., Berkeley), AG(California Univ., Berkeley), AH(Mount Stromlo and Siding Spring Observatoires, Canberra, Australia), AI(Mount Stromlo and Siding Spring Observatoires, Canberra, Australia), AJ(Mount Stromlo and Siding Spring Observatoires, Canberra, Australia)
%J After the first three minutes
%V 222
%D 1991
%8 April 01, 1991
%P 446
%K Black Holes (Astronomy); Brown Dwarf Stars; Dark Matter; Galactic
Halos; Gas Giant Planets; Milky Way Galaxy; Astronomical Photometry;
Gravitational Lenses; Light Curve; Stellar Mass; Telescopes;
Astrophysics; 98.50.Lh; 98.50.Mi; 97.20.Vs; 97.60.Lf; Low luminosity
stars subdwarfs and brown dwarfs; Black holes
%U https://ui.adsabs.harvard.edu/abs/1991AIPC..222..446B
%X Massive Compact Halo Objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Paczynski noted that these objects (dubbed MACHOs) can be detected via gravitational microlensing of stars in the Magellanic Clouds with the caveat that only about one in 106 stars will be lensed at any given time. Our group is currently involved in constucting a dedicated observing system at the Mount Stromlo Observatory in Austrilia. We will use a refurbished 1.27 meter telescope and an innovative two-color CCD camera with 3.4×107 pixels to monitor 106-107 stars in the Magellanic Clouds. During the first year of operation (1991-1992), we hope to detect (or rule out) objects in the mass range 0.001 Msolar&lt;=M&lt;=0.1Msolar, and after five years, we hope to have covered the range 10-6Msolar&lt;M&lt;~100Msolar.
%R 10.1063/1.40412
%@ 0094-243X


%0 Journal Article
%T Does antimatter fall with the same acceleration as ordinary matter?
%A Adelberger, E. G.
%A Heckel, B. R.
%A Stubbs, C. W.
%A Su, Y.
%+ AA(Washington, University, Seattle), AB(Washington, University, Seattle), AC(Washington, University, Seattle), AD(Washington, University, Seattle)
%J Physical Review Letters
%V 66
%D 1991
%8 February 01, 1991
%P 850
%K Acceleration (Physics); Antimatter; Gravitational Fields; Quantum
Theory; Relativistic Particles; Antiparticles; Bosons; Gravitational
Effects; Gravitons; Physics (General); ACCELERATION (PHYSICS);
ANTIMATTER; GRAVITATIONAL FIELDS; QUANTUM THEORY; RELATIVISTIC
PARTICLES; ANTIPARTICLES; BOSONS; GRAVITATIONAL EFFECTS; GRAVITONS;
04.80.+z; 04.60.+n; 04.90.+e; Other topics in general relativity and
gravitation
%U https://ui.adsabs.harvard.edu/abs/1991PhRvL..66..850A
%X It is shown that equivalence-principle and inverse-square-law experiments using ordinary matter probe the gravivector acceleration of antimatter in the same ways as do direct measurements of antimatter in free falls. It is also shown that these ordinary-matter experiments set stringent upper limits on the predicted gravivector acceleration of antimatter that lie well below those expected from the present generation of direct antimatter experiments. It is pointed out that there is no evidence for unusual gravitational behavior of antimatter or for quantum-gravity-inspired models which postulate the existence of low-mass spin-0 and spin-1 partners of the graviton.
%R 10.1103/PhysRevLett.66.850
%@ 0031-9007


%0 Journal Article
%T Searches for new macroscopic forces
%A Adelberger, E. G.
%A Heckel, B. R.
%A Stubbs, C. W.
%A Rogers, W. F.
%J Annual Review of Nuclear and Particle Science
%V 41
%D 1991
%8 January 01, 1991
%P 269
%U https://ui.adsabs.harvard.edu/abs/1991ARNPS..41..269A
%R 10.1146/annurev.ns.41.120191.001413
%@ 0163-8998


%0 Journal Article
%T Testing the equivalence principle in the field of the Earth: Particle physics at masses below 1 μeV\?
%A Adelberger, E. G.
%A Stubbs, C. W.
%A Heckel, B. R.
%A Su, Y.
%A Swanson, H. E.
%A Smith, G.
%A Gundlach, J. H.
%A Rogers, W. F.
%+ AA(Physics Department, University of Washington, Seattle, Washington 98195), AB(Physics Department, University of Washington, Seattle, Washington 98195), AC(Physics Department, University of Washington, Seattle, Washington 98195), AD(Physics Department, University of Washington, Seattle, Washington 98195), AE(Physics Department, University of Washington, Seattle, Washington 98195), AF(Physics Department, University of Washington, Seattle, Washington 98195), AG(Physics Department, University of Washington, Seattle, Washington 98195), AH(Department of Physics and Astronomy, State University of New York at Geneseo, Geneseo, New York 14454)
%J Physical Review D
%V 42
%D 1990
%8 November 01, 1990
%P 3267
%U https://ui.adsabs.harvard.edu/abs/1990PhRvD..42.3267A
%X A sensitive, systematic search for feeble, macroscopic forces arising from the exchange of hypothetical ultra-low-mass bosons was made by observing the differential acceleration of two different test body pairs toward two different sources. Our differential accelerometer-a highly symmetric, continuously rotating torsion balance-incorporated several innovations that effectively suppressed systematic errors. All known sources of systematic error were demonstrated to be negligible in comparison to our fluctuating errors which are roughly 7 times larger than the fundamental limit set by the fact that we observe an oscillator at room temperature with a given damping time. Our 1σ limits on the horizontal differential acceleration of Be/Al or Be/Cu test body pairs in the field of the Earth, ∆a<SUB>⊥</SUB>=(2.1+/-2.1)×10<SUP>-11</SUP> cm s<SUP>-2</SUP> and ∆a<SUB>⊥</SUB>=(0.8+/-1.7)×10<SUP>-11</SUP> cm s<SUP>-2</SUP>, respectively, set improved bounds on Yukawa interactions mediated by bosons with masses ranging between m<SUB>b</SUB>c<SUP>2</SUP>~=3×10<SUP>-18</SUP> and m<SUB>b</SUB>c<SUP>2</SUP>~=1×10<SUP>-6</SUP> eV. For example, our constraints on infinite-range vector interactions with charges of B and of B-L are roughly 10 and 2 times more sensitive than those obtained by Roll, Krotkov, and Dicke using the field of the Sun. Furthermore we set stringent constraints down to λ=1 m, while those of solar experiments are weak for λ&lt;1 AU. In terms of the weak equivalence principle in the field of the Earth, our 1σ result corresponds to m<SUB>i</SUB>/m<SUB>g</SUB>(Cu)-m<SUB>i</SUB>/m<SUB>g</SUB>(Be)=(0.2+/-1.0)×10<SUP>-11</SUP>. Our results also yield stringent constraints on the nonsymmetric gravitation theory of Moffat and on the anomalous acceleration of antimatter in proposed ``quantum gravity'' models, and have implications for lunar-ranging tests of the strong equivalence principle. Our 1σ limit on the differential acceleration of Be/Al test body pairs toward a 1.5 Mg Pb laboratory source, ∆a=(-0.15+/-1.31)×10<SUP>-10</SUP> cm s<SUP>-2</SUP>, provides constraints on Yukawa interactions with ranges down to 10 cm, and on interactions whose charge is B-2L.
%R 10.1103/PhysRevD.42.3267
%@ 1550-79980556-2821


%0 Journal Article
%T A cryogenic phonon detector with simultaneous measurement of phonons and ionization
%A Wang, N.
%A Shutt, T.
%A Cummings, A.
%A Sadoulet, B.
%A Haller, E. E.
%A Barnes, P.
%A Emes, J.
%A Giraud-Héraud, Y.
%A Lange, A.
%A Rich, J.
%A Ross, R.
%A Stubbs, C.
%+ AA(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AB(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AC(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AD(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AE(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AF(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AG(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AH(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AI(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AJ(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AK(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA), AL(Center for Particle Astrophysics and Department of Physics, University of California, and Physics Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd, Berkeley, Ca 94720, USA)
%J Physica B Condensed Matter
%V 165
%D 1990
%8 August 01, 1990
%P 3
%U https://ui.adsabs.harvard.edu/abs/1990PhyB..165....3W
%X One way to detect dark matter particles from the halo of our galaxy is to detect phonons generated by dark matter particle interaction in a crystal. We report on our efforts to develop a phonon detector operating at 20 mK. We present our recent results on the simultaneous measurement of phonons and ionization, which may provide an effective way to reject background in dark matter search.
%R 10.1016/S0921-4526(90)80851-9
%@ 0921-4526


%0 Conference Proceedings
%T Fluorophore lifetime distributions as a probe of lipid bilayer organization
%A Stubbs, Christopher W.
%A Williams, B. W.
%A Ho, Cojen
%+ AA(Thomas Jefferson Univ., USA), AB(Bucknell College, USA), AC(Thomas Jefferson Univ., USA)
%J Time-Resolved Laser Spectroscopy in Biochemistry II
%V 1204
%D 1990
%8 May 01, 1990
%P 448
%U https://ui.adsabs.harvard.edu/abs/1990SPIE.1204..448S
%X The fluorescence decay of membrane lipid bilayer probes are influenced by the environment of the probe and therefore by the properties of the bilayer in which it resides. Traditionally the fluorescence decay has been analyzed in the form of a multi-exponential. Analysis in the form of continuous distributions can provide a useful alternative to this approach since it introduces a new parameter, the distributional width. The physical basis underlying the distributional width, the fluorophore "environmental heterogeneity", arises from organizational aspects, compositional diversity and solvent effects. The "sampling" of environmental heterogeneity will depend on the intrinsic fluorescence lifetime, the lipid rate of motion and fluorophore charge and shape factors. We have found a good correlation of the distributional width with a number of bilayer properties. Thus as we increase the complexity of a bilayer the distributional width becomes broader, in order, from a single phospholipid molecular species, mixture of species, mixture of classes (i.e. PC+ PE etc) and species to intact natural membranes (i.e. including proteins and bilayer organizational factors). More recently we have been able to show that the protein-lipid interface itself can act as a source of fluorophore heterogeneity. Suggesting the possibility of spectroscopically isolating a region of the membrane of particular interest in the modulation of membrane processes. There are still a number of uncertainties in assigning a distributional width to a particular bilayer property. For example in comparing bilayers they could be compared at the same temperature or at the same temperature above the respective gel-liquid phase transition temperatures. In fact with regard to the relative degree of environmental heterogeneity sampled by the fluorophore it may be better to make such types of comparisons at the same respective rates of lipid motion since the rate of lipid motion is a key factor governing the sampling of environmental heterogeneity. Using this approach in the example of increasing levels of unsaturation our results suggest that unsaturation introduces structural diversity into lipid bilayers.
%R 10.1117/12.17708
%@ 0277-786X


%0 Journal Article
%T Experimental bounds on interactions mediated by ultralow-mass bosons.
%A Heckel, B. R.
%A Adelberger, E. G.
%A Stubbs, C. W.
%A Su, Y.
%A Swanson, H. E.
%A Smith, G.
%A Rogers, W. F.
%+ AA(Washington, University, Seattle), AB(Washington, University, Seattle), AC(Washington, University, Seattle), AD(Washington, University, Seattle), AE(Washington, University, Seattle)
%J Physical Review Letters
%V 63
%D 1989
%8 December 01, 1989
%P 2705
%K Accelerometers; Bosons; Elementary Particle Interactions; Particle
Mass; Crystal Oscillators; Fourier Analysis; Nuclear and High-Energy
Physics; Gravitation Theory: Tests; 04.90.+e; 04.80.+z; 14.80.Er; Other
topics in general relativity and gravitation
%U https://ui.adsabs.harvard.edu/abs/1989PhRvL..63.2705H
%X The authors have used a rotating torsion balance to search for feeble forces arising from exchange of ultralow-mass bosons. Their limits on the differential horizontal acceleration of Be/Al or Be/Cu test-body pairs in the field of the Earth, ∆a<SUB>⊥</SUB> = (1.5±2.3)×10<SUP>-11</SUP> cm s<SUP>-2</SUP> and ∆a<SUB>⊥</SUB> = (0.9±1.7)×10<SUP>-11</SUP> cm s<SUP>-2</SUP>, respectively, set improved bounds on interactions mediated by bosons with masses ranging between 10<SUP>-17</SUP> and 10<SUP>-6</SUP>eV.
%R 10.1103/PhysRevLett.63.2705
%@ 0031-9007


%0 Journal Article
%T Limits on composition-dependent interactions using a laboratory source: is there a "fifth force" coupled to isospin?
%A Stubbs, C. W.
%A Adelberger, E. G.
%A Heckel, B. R.
%A Rogers, W. F.
%A Swanson, H. E.
%A Watanabe, R.
%A Gundlach, J. H.
%A Raab, F. J.
%+ AA(Washington, University, Seattle), AB(Washington, University, Seattle), AC(Washington, University, Seattle), AD(Washington, University, Seattle), AE(Washington, University, Seattle)
%J Physical Review Letters
%V 62
%D 1989
%8 February 01, 1989
%P 609
%K Acceleration (Physics); Composition (Property); Field Theory
(Physics); Force; Lead (Metal); Magnetic Moments; Mass Balance;
Mechanical Measurement; Pendulums; Physics (General); Gravitation
Theory: Tests; 04.90.+e; 14.80.Pb; Other topics in general relativity
and gravitation
%U https://ui.adsabs.harvard.edu/abs/1989PhRvL..62..609S
%X Previous "fifth-force" experiments searched for differential acceleration of test bodies placed near terrestrial sources. Because these sources have N≍Z the results had little sensitivity to forces coupled to B-2L = N-Z. The authors searched for such forces by placing a 1 ton Pb source close to a Be/Al torsion balance. No evidence for an isospin-coupled force was found.
%R 10.1103/PhysRevLett.62.609
%@ 0031-9007


%0 Conference Proceedings
%T Eöt-Wash constraints on multiple Yukawa interactions and on a coupling to "Isospin"
%A Stubbs, C. W.
%J Tests of Fundamental Laws in Physics
%D 1989
%8 January 01, 1989
%P 473
%U https://ui.adsabs.harvard.edu/abs/1989tflp.conf..473S


%0 Journal Article
%T Constraints of proposed spin-0 and spin-1 partners of the graviton
%A Stubbs, C. W.
%A Gregory, E. C.
%A Adelberger, E. G.
%+ AA(Washington, University, Seattle), AB(Washington, University, Seattle), AC(California Institute of Technology, Pasadena)
%J Physical Review Letters
%V 61
%D 1988
%8 November 01, 1988
%P 2409
%K Earth Gravitation; Gravitons; Quantum Theory; Acceleration (Physics);
Beryllium; Constraints; Copper; Topography; 04.90.+e; 14.80.Pb; Physics
(General); Other topics in general relativity and gravitation
%U https://ui.adsabs.harvard.edu/abs/1988PhRvL..61.2409S
%X Previous torsion-balance data are used to constrain the quantum-gravity prediction that ordinary matter should experience the effect of, in addition to Newtonian gravity, composition-dependent attractive and repulsive Yukawa interactions. Results are presented for the difference between the ranges of the proposed attractive and repulsive interactions. It is found that the attractive and repulsive forces calculated from earth-gravity studies do not exhibit the predicted composition dependence.
%R 10.1103/PhysRevLett.61.2409
%@ 0031-9007


%0 Journal Article
%T Shielding the ``fifth force''\?
%A Watanabe, R.
%A Stubbs, C. W.
%A Adelberger, E. G.
%+ AA(Department of Physics, FM-15, University of Washington, Seattle, Washington 98195), AB(Department of Physics, FM-15, University of Washington, Seattle, Washington 98195), AC(Department of Physics, FM-15, University of Washington, Seattle, Washington 98195)
%J Physical Review Letters
%V 61
%D 1988
%8 October 01, 1988
%P 2152
%K 04.90.+e; 14.80.Pb; Other topics in general relativity and
gravitation
%U https://ui.adsabs.harvard.edu/abs/1988PhRvL..61.2152W
%X A Comment on the Letter by E. Fischback et al., Phys. Rev. Lett. 60, 74 (1988).
%R 10.1103/PhysRevLett.61.2152
%@ 0031-9007


%0 Journal Article
%T Comment on “a new approach to the question of the fifth force”
%A Adelberger, E. G.
%A Stubbs, C. W.
%+ AA(Bridge Laboratory 161-33, Caltech, Pasadena, CA 91125, USA), AB(Department of Physics, FM-15, University of Washington, Seattle, WA 98195, USA)
%J Physics Letters A
%V 132
%D 1988
%8 September 01, 1988
%P 91
%U https://ui.adsabs.harvard.edu/abs/1988PhLA..132...91A
%X We show that, contrary to a recent suggestion, a photon redshift result at the 10 <SUP>-4</SUP> level would not provide a constraint on a possible “fifth force” that is competitive with existing results from experiments using massive test bodies.
%R 10.1016/0375-9601(88)90259-9
%@ 0375-9601


%0 Thesis
%T a Search for a New Composition-Dependent Interaction: AN Experimental Test of the 'fifth Force' Hypothesis.
%A Stubbs, Christopher William
%+ AA(UNIVERSITY OF WASHINGTON.)
%J Ph.D. Thesis
%D 1988
%8 January 01, 1988
%K Physics: General
%U https://ui.adsabs.harvard.edu/abs/1988PhDT........78S
%X We have performed a torsion balance experiment to search for new composition-dependent interactions. We minimized potential sources of systematic error by configuring the torsion pendulum as a symmetric array of four test objects (of two different materials) that were virtually identical in all respects other than composition. We have explicitly tested for thermal, magnetic, mechanical and gravitational effects that could produce spurious results and are confident that our experiment has not suffered from unidentified sources of systematic error. Furthermore, we continuously rotated the apparatus so that any torques on the composition dipole arising from the horizontal component of a composition-dependent force would be modulated at the rotation rate. The experiment was performed on a hillside to increase its sensitivity to forces of intermediate range, such as the 'fifth force' proposed by Fischbach et al. We have compared the horizontal acceleration differences for two material pairs: Be-Cu and Be-Al. Our null results unambiguously rule out the original 'fifth force' conjecture of a Yukawa coupling to baryon number with a strength 100 times weaker than gravity and a range between 10 and 1000 m. We have also established stringent constraints on a more general coupling to a linear combination of baryon and lepton number.


%0 Journal Article
%T Erratum: New constraints on composition-dependent interactions weaker than gravity [Phys. Rev. Lett. 59, 849 (1987)]
%A Adelberger, E. G.
%A Stubbs, C. W.
%A Rogers, W. F.
%A Raab, F. J.
%A Heckel, B. R.
%A Gundlach, J. H.
%A Swanson, H. E.
%A Watanabe, R.
%J Physical Review Letters
%V 59
%D 1987
%8 October 01, 1987
%P 1790
%U https://ui.adsabs.harvard.edu/abs/1987PhRvL..59.1790A
%R 10.1103/PhysRevLett.59.1790.4
%@ 0031-9007


%0 Journal Article
%T New constraints on composition-dependent interactions weaker than gravity
%A Adelberger, E. G.
%A Stubbs, C. W.
%A Rogers, W. F.
%A Raab, F. J.
%A Heckel, B. R.
%+ AA(Washington, University, Seattle), AB(Washington, University, Seattle), AC(Washington, University, Seattle), AD(Washington, University, Seattle), AE(Washington, University, Seattle)
%J Physical Review Letters
%V 59
%D 1987
%8 August 01, 1987
%P 849
%K Baryons; Weak Interactions (Field Theory); Aluminum; Amplitudes;
Beryllium; Copper; Water; 04.90.+e; 14.80.Pb; Physics (General); Other
topics in general relativity and gravitation
%U https://ui.adsabs.harvard.edu/abs/1987PhRvL..59..849A
%X Published data from two recent experiments testing the fifth-force hypothesis are analyzed theoretically, and new results are reported. It is suggested that both (1) the positive result of Thieberger (1987) using a hollow Cu sphere floating in water and (2) the negative result of Stubbs et al. (1987) using Cu and Be test bodies in a torsion balance operated on a hillside could be explained in terms of a single Yukawa interaction with a nonzero value of the mixing angle theta5. However, the results of a new torsion-balance experiment with Al and Be test bodies appear to rule out such an interaction, the only possible exception being an interaction coupled to q5 and limited to a narrow region with theta5 near -63 deg.
%R 10.1103/PhysRevLett.59.849
%@ 0031-9007


%0 Journal Article
%T Search for an intermediate-range interaction
%A Stubbs, C. W.
%A Adelberger, E. G.
%A Raab, F. J.
%A Gundlach, J. H.
%A Heckel, B. R.
%A McMurry, K. D.
%A Swanson, H. E.
%A Watanabe, R.
%+ AA(Physics Department, University of Washington, Seattle, Washington 98195), AB(Physics Department, University of Washington, Seattle, Washington 98195), AC(Physics Department, University of Washington, Seattle, Washington 98195), AD(Physics Department, University of Washington, Seattle, Washington 98195), AE(Physics Department, University of Washington, Seattle, Washington 98195), AF(Physics Department, University of Washington, Seattle, Washington 98195), AG(Physics Department, University of Washington, Seattle, Washington 98195), AH(Physics Department, University of Washington, Seattle, Washington 98195)
%J Physical Review Letters
%V 58
%D 1987
%8 March 01, 1987
%P 1070
%K 04.90.+e; 14.80.Pb; Other topics in general relativity and
gravitation
%U https://ui.adsabs.harvard.edu/abs/1987PhRvL..58.1070S
%X We have placed a torsion balance (containing two Be and two Cu test bodies) on a hillside to search for intermediate-range forces that couple to baryon number. Our results constrain (at 1σ) the strength of such an interaction to be ||α~||&lt;=1×10<SUP>-4</SUP> for ranges 250&lt;=λ&lt;=1400 m and ||α~||&lt;=1×10<SUP>-3</SUP> for ranges 30&lt;λ&lt;250 m.
%R 10.1103/PhysRevLett.58.1070
%@ 0031-9007


%0 Journal Article
%T The application of fluorescence decay measurements in studies of biological systems
%A Meech, S.
%A Stubbs, C.
%A Phillips, D.
%J IEEE Journal of Quantum Electronics
%V 20
%D 1984
%8 December 01, 1984
%P 1343
%U https://ui.adsabs.harvard.edu/abs/1984IJQE...20.1343M
%R 10.1109/JQE.1984.1072320
%@ 0018-9197