Author
Gordon Bowden
Bio: Gordon Bowden is an academic researcher from Stanford University. The author has contributed to research in topics: Large Synoptic Survey Telescope & Telescope. The author has an hindex of 5, co-authored 9 publications receiving 96 citations.
Papers
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TL;DR: The Large Synoptic Survey Telescope (LSST) is a large aperture, wide-field facility designed to provide deep images of half the sky every few nights as mentioned in this paper, which is only a single instrument on the telescope, which is mounted close to the secondary mirror, and points down toward the tertiary.
Abstract: The Large Synoptic Survey Telescope (LSST) is a large aperture, wide-field facility designed to provide deep images of
half the sky every few nights. There is only a single instrument on the telescope, a 9.6 square degree visible-band
camera, which is mounted close to the secondary mirror, and points down toward the tertiary. The requirements of the
LSST camera present substantial technical design challenges. To cover the entire 0.35 to 1 μm visible band, the camera
incorporates an array of 189 over-depleted bulk silicon CCDs with 10 μm pixels. The CCDs are assembled into 3 x 3
"rafts", which are then mounted to a silicon carbide grid to achieve a total focal plane flatness of 15 μm p-v. The CCDs
have 16 amplifiers per chip, enabling the entire 3.2 Gigapixel image to be read out in 2 seconds. Unlike previous
astronomical cameras, a vast majority of the focal plane electronics are housed in the cryostat, which uses a mixed
refrigerant Joule-Thompson system to maintain a -100oC sensor temperature. The shutter mechanism uses a 3 blade
stack design and a hall-effect sensor to achieve high resolution and uniformity. There are 5 filters stored in a carousel
around the cryostat and the auto changer requires a dual guide system to control its position due to severe space
constraints. This paper presents an overview of the current state of the camera design and development plan.
47 citations
11 Jan 1996-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: Fully automated movers capable of positioning beamline magnets weighing more than 100 kg to a few microns over several millimeters have been designed and built for the Final Focus Test Beam at SLAC.
Abstract: Fully automated movers capable of positioning beamline magnets weighing more than 100 kg to a few microns over several millimeters have been designed and built for the Final Focus Test Beam at SLAC. These movers also provide incremental motion as small as a few tenths of a micron. We review the basic design considerations, the hardware realization of the movers, and the extensive tests conducted on these electromechanical stages. Suggestions for the improvement and augmentation of such movers are also given.
21 citations
TL;DR: In this paper, a test of planar spark counters (PSCs) at the PEP electron-positron storage ring showed the following: on-line time-of-flight resolution was below 200 ps, coordinate resolutions better than 4 mm, both limited to these values by the resistivity of the semiconducting glass and the electronics used.
12 citations
15 Jun 1989-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors used magnetic dipoles to scan the beams across the carbon fibres and measured the beam profiles in horizontal and vertical axes by using charge-sensitive amplifiers.
Abstract: Retractable targets of carbon fibres with nominal diameters of 30, 7 and 4.5 μm have been in use at the collision point of the SLC (the SLAC Linear Collider). The target mechanism is compatible with the Mark II detector now in place at the collision point. Beam profiles are measured in horizontal and vertical axes by using magnetic dipoles to scan the beams across the fibres. Two signal detection mechanisms are available. Electron emission from the fibres is measured with the help of charge-sensitive amplifiers. Bremsstrahlung from the fibres is detected by downstream counters. Examples of measurements are given, and limits on the use of the techniques are discussed.
11 citations
TL;DR: The LSST camera as discussed by the authors is a tightly packaged, hermetically sealed system that is cantilevered into the main beam of the LSST telescope and is comprised of three refractive lenses, on-board storage for five large filters, a high-precision shutter, and a cryostat that houses the 3.2 giga-pixel CCD focal plane along with its support electronics.
Abstract: The LSST camera is a tightly packaged, hermetically-sealed system that is cantilevered into the main beam of the LSST telescope. It is comprised of three refractive lenses, on-board storage for five large filters, a high-precision shutter, and a cryostat that houses the 3.2 giga-pixel CCD focal plane along with its support electronics. The physically large optics and focal plane demand large structural elements to support them, but the overall size of the camera and its components must be minimized to reduce impact on the image stability. Also, focal plane and optics motions must be minimized to reduce systematic errors in image reconstruction. Design and analysis for the camera body and cryostat will be detailed.
7 citations
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01 May 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The BELLE detector for experiments at KEKB, a high luminosity, energy asymmetric B-factory, is now being constructed at KEK, and an overview of the detector systems and their status is presented.
Abstract: The BELLE detector for experiments at KEKB, a high luminosity, energy asymmetric B-factory, is now being constructed at KEK. An overview of the detector systems and their status is presented.
1,057 citations
Fermilab1, Ohio State University2, University College London3, Autonomous University of Barcelona4, University of Pennsylvania5, Carnegie Learning6, University of Michigan7, Institut de Ciències de l'Espai8, Texas A&M University9, Lawrence Berkeley National Laboratory10, University of Chicago11, University of Illinois at Urbana–Champaign12, Australian Astronomical Observatory13, Argonne National Laboratory14, SLAC National Accelerator Laboratory15, Catalan Institution for Research and Advanced Studies16, Institute of Cosmology and Gravitation, University of Portsmouth17, California Institute of Technology18, Brookhaven National Laboratory19, Stanford University20
TL;DR: The Dark Energy Camera as mentioned in this paper was designed and constructed by the Dark Energy Survey Collaboration, and meets or exceeds the stringent requirements designed for the wide-field and supernova surveys for which the collaboration uses it.
Abstract: The Dark Energy Camera is a new imager with a 2.2-degree diameter field of view mounted at the prime focus of the Victor M. Blanco 4-meter telescope on Cerro Tololo near La Serena, Chile. The camera was designed and constructed by the Dark Energy Survey Collaboration, and meets or exceeds the stringent requirements designed for the wide-field and supernova surveys for which the collaboration uses it. The camera consists of a five element optical corrector, seven filters, a shutter with a 60 cm aperture, and a CCD focal plane of 250 micron thick fully-depleted CCDs cooled inside a vacuum Dewar. The 570 Mpixel focal plane comprises 62 2kx4k CCDs for imaging and 12 2kx2k CCDs for guiding and focus. The CCDs have 15 microns x15 microns pixels with a plate scale of 0.263 arc sec per pixel. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 seconds with 6-9 electrons readout noise. This paper provides a technical description of the camera's engineering, construction, installation, and current status.
844 citations
TL;DR: Previous theoretical results suggesting that lens speed and field of view can be scale independent in microcamera-based imagers resolving up to 50 gigapixels are confirmed, suggesting that Ubiquitous gigapixel cameras may transform the central challenge of photography from the question of where to point the camera to that of how to mine the data.
Abstract: The AWARE-2 camera uses a parallel array of microcameras to capture one-gigapixel images at three frames per minute.
290 citations
TL;DR: The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe as discussed by the authors.
Abstract: The discovery of the accelerating universe in the late 1990s was a watershed moment in modern cosmology, as it indicated the presence of a fundamentally new, dominant contribution to the energy budget of the universe. Evidence for dark energy, the new component that causes the acceleration, has since become extremely strong, owing to an impressive variety of increasingly precise measurements of the expansion history and the growth of structure in the universe. Still, one of the central challenges of modern cosmology is to shed light on the physical mechanism behind the accelerating universe. In this review, we briefly summarize the developments that led to the discovery of dark energy. Next, we discuss the parametric descriptions of dark energy and the cosmological tests that allow us to better understand its nature. We then review the cosmological probes of dark energy. For each probe, we briefly discuss the physics behind it and its prospects for measuring dark energy properties. We end with a summary of the current status of dark energy research.
187 citations
01 Jan 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the results of experimental tests on resistive plate counters of 6 × 0.5 m2 area are reported, showing that this technique is suitable for time of flight measurements over large areas with a resolution of the order of 1 ns.
Abstract: Results of experimental tests on resistive plate counters of 6 × 0.5 m2 area are reported. The results show that this technique is suitable for time of flight measurements over large areas with a resolution of the order of 1 ns.
185 citations