[Show abstract][Hide abstract] ABSTRACT: The focus of this report is on the opportunities enabled by the combination
of LSST, Euclid and WFIRST, the optical surveys that will be an essential part
of the next decade's astronomy. The sum of these surveys has the potential to
be significantly greater than the contributions of the individual parts. As is
detailed in this report, the combination of these surveys should give us
multi-wavelength high-resolution images of galaxies and broadband data covering
much of the stellar energy spectrum. These stellar and galactic data have the
potential of yielding new insights into topics ranging from the formation
history of the Milky Way to the mass of the neutrino. However, enabling the
astronomy community to fully exploit this multi-instrument data set is a
challenging technical task: for much of the science, we will need to combine
the photometry across multiple wavelengths with varying spectral and spatial
resolution. We identify some of the key science enabled by the combined surveys
and the key technical challenges in achieving the synergies.
[Show abstract][Hide abstract] ABSTRACT: 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.
Proceedings of SPIE - The International Society for Optical Engineering 07/2014; DOI:10.1117/12.2057411 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The design of the Large Synoptic Survey Telescope (LSST) requires a
camera system of unprecedented size and complexity. Achieving the
science goals of the LSST project, through design, fabrication,
integration, and operation, requires a thorough understanding of the
camera performance. Essential to this effort is the camera modeling
which defines the effects of a large number of potential mechanical,
optical, electronic or sensor variations which can only be captured with
sophisticated instrument modeling that incorporates all of the crucial
parameters. This paper presents the ongoing development of LSST camera
instrument modeling and details the parametric issues and attendant
analysis involved with this modeling.
Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.926611 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A tightly focused beam on target is required in the muon collider/neutrino factory study. Specifically, up to 16 TP (1 TP = 10 12 protons) per pulse of a 24 GeV proton beam are to be delivered on target, with a pulse length of a few microseconds and a beam spot of 0.5 mm rms sigma. Experiment E951 at BNL was set up to explore the potential of various target materials. Optimization of the pion production led to the consideration of low-Z materials as potential targets. Thus, in the first phase of the E951 experiment, graphite and carbon-carbon composite targets were exposed to the AGS beam and their response to the induced thermal shock was studied. This paper presents theoretical prediction results as well as experimental results and makes an assessment of the abilities of prediction models to capture the dynamic response of the solid target. 1.
[Show abstract][Hide abstract] ABSTRACT: The LSST camera, which will be the largest digital camera built to date,
presents a number of novel challenges. The field of view will be 3.5
degrees in diameter and will be sampled by a 3.2 billion pixel array of
sensors to be read-out in under 2 seconds, which leads to demanding
constraints on the sensor architecture and read-out electronics. The
camera also incorporates three large refractive lenses, an array of five
wide-band large filters mounted on a carousel, and a mechanical shutter.
Given the fast optical beam (f/1.2) and tight tolerances for image
quality and throughput specifications, the requirements on the optical
design, assembly and alignment, and contamination control of the optical
elements and focal plane are crucial. We present an overview of the LSST
camera, with an emphasis on models of camera image quality and
throughput performance that are characterized by various analysis
packages and design considerations.
[Show abstract][Hide abstract] ABSTRACT: The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project
intended to demonstrate the only practical solution to providing high
brilliance beams necessary for a neutrino factory or muon collider. MICE is
under development at the Rutherford Appleton Laboratory (RAL) in the United
Kingdom. It comprises a dedicated beamline to generate a range of input muon
emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a
pure muon beam. The emittance of the incoming beam will be measured in the
upstream magnetic spectrometer with a scintillating fiber tracker. A cooling
cell will then follow, alternating energy loss in Liquid Hydrogen (LH2)
absorbers to RF cavity acceleration. A second spectrometer, identical to the
first, and a second muon identification system will measure the outgoing
emittance. In the 2010 run at RAL the muon beamline and most detectors were
fully commissioned and a first measurement of the emittance of the muon beam
with particle physics (time-of-flight) detectors was performed. The analysis of
these data was recently completed and is discussed in this paper. Future steps
for MICE, where beam emittance and emittance reduction (cooling) are to be
measured with greater accuracy, are also presented.
[Show abstract][Hide abstract] ABSTRACT: The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a refractive camera design with 3 lenses (0.69-1.55m) and a set of broadband filters/corrector lenses. Performance is excellent over a 9.6 square degree field and ultraviolet to near infrared wavelengths. We describe the image quality error budget analysis methodology which includes effects from optical and optomechanical considerations such as index inhomogeneity, fabrication and null-testing error, temperature gradients, gravity, pressure, stress, birefringence, and vibration.
Proceedings of SPIE - The International Society for Optical Engineering 07/2010; DOI:10.1117/12.857682 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Limits on the anomalous WWγ and WWZ couplings are presented from a simultaneous fit to the data samples of three gauge boson pair final states in pp̅ collisions at √s=1.8TeV: Wγ production with the W boson decaying to eν or μν, W boson pair production with both of the W bosons decaying to eν or μν, and WW or WZ production with one W boson decaying to eν and the other W boson or the Z boson decaying to two jets. Assuming identical WWγ and WWZ couplings, 95% C.L. limits on the anomalous couplings of -0.30<Δκ<0.43 (λ=0) and -0.20<λ<0.20 (Δκ=0) are obtained using a form factor scale Λ=2.0TeV. Limits found under other assumptions on the relationship between the WWγ and WWZ couplings are also presented.
[Show abstract][Hide abstract] ABSTRACT: The LSST design is driven by four science themes and desire to engage
broad science community and general public in LSST data exploration. The
current baseline design, with an 8.4m (6.7m effective) primary mirror
and a 9.6 sq.deg. field of view, will allow about 10,000 square degrees
of sky to be visited twice per night, with an effective depth of r=24.5
per visit, every three nights. The system is designed to yield high
image quality as well as superb astrometric and photometric accuracy,
and will regularly produce three classes of data products. Level 1 data
products are generated continuously every observing night, including
alerts to objects that have changed flux or position, that will be
released within 60 seconds. Level 2 data products will be made available
as annual Data Releases and will include images and measurements of
positions, fluxes, and shapes, as well as variability information such
as orbital parameters for moving objects. The LSST Data Management
System will also facilitate the creation of Level 3 data products by
science teams external to the project by providing suitable Applications
Programming Interfaces (APIs), about 50 teraflops of user-dedicated
processing capability and 12 petabytes of user-dedicated storage. The
key aspect of these capabilities is that they will reside "next to" the
LSST data, avoiding the latency associated with downloads.
[Show abstract][Hide abstract] ABSTRACT: The Large Synoptic Survey Telescope is a large aperture, wide-field, ground-based telescope that will survey half the sky every few nights in six visible bands. The etendue of the LSST system (an optical measure of the information gathering capability) is over 320 m2/deg2 and is far greater than any other telescope. The LSST system provides an end-to-end astronomical survey facility to acquire process, analyze, catalog, and preserve the world's largest database of optical astronomical data. LSST will also open the time domain for studies of transient and moving objects. Multiple Data Access Centers will be strategically located to provide the user community with high-speed, open access to the many Petabytes of new information generated each year of the planned ten year survey. Scheduled to have first telescope light in early 2014, the LSST Observatory will be sited atop Cerro Pachón in Northern Chile. All three of the large mirrors required for the LSST are currently in production.
[Show abstract][Hide abstract] ABSTRACT: The LSST camera is a wide-field optical (0.35-1mum) imager designed to provide a 3.5 degree FOV with 0.2 arcsecond/pixel sampling. The detector format will be a circular mosaic providing approximately 3.2 Gigapixels per image. The camera includes a filter mechanism and shuttering capability. It is positioned in the middle of the telescope where cross-sectional area is constrained by optical vignetting and where heat dissipation must be controlled to limit thermal gradients in the optical beam. The fast f/1.2 beam will require tight tolerances on the focal plane mechanical assembly. The focal plane array operates at a temperature of approximately -100°C to achieve desired detector performance. The focal plane array is contained within a cryostat which incorporates detector front-end electronics and thermal control. The cryostat lens serves as an entrance window and vacuum seal for the cryostat. Similarly, the camera body lens serves as an entrance window and gas seal for the camera housing, which is filled with a suitable gas to provide the operating environment for the shutter and filter change mechanisms. The filter carousel accommodates 5 filters, each 75 cm in diameter, for rapid exchange without external intervention.
Proceedings of SPIE - The International Society for Optical Engineering 08/2008; DOI:10.1117/12.789947 · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We study the flavor-changing-neutral-current process c-->u micro(+) micro(-) using 1.3 fb(-1) of pp[over ] collisions at square root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D(s)(+) and D(+)-->phipi(+) --> micro(+)micro(-)pi(+) final states with significance greater than 4 standard deviations above background for the D(+) state. We search for the continuum neutral-current decay of D(+)-->pi(+) micro(+) micro(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D(+) --> pi(+) micro(+) micro(-))<3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c--> u micro(+) micro(-) transition.