We present the first results from an ongoing survey for damped Lyman-α systems (DLAs) in the spectra of z > 2 quasars observed in the course of the Baryon Oscillation Spectroscopic Survey (BOSS), ...which is part of the Sloan Digital Sky Survey (SDSS) III. Our full (non-statistical) sample, based on Data Release 9, comprises 12 081 systems with log N(H i) ≥ 20, out of which 6839 have log N(H i) ≥ 20.3. This is the largest DLA sample ever compiled, superseding that from SDSS-II by a factor of seven. Using a statistical sub-sample and estimating systematics from realistic mock data, we probe the N(H i) distribution at ⟨z⟩ = 2.5. Contrary to what is generally believed, the distribution extends beyond 1022 cm-2 with a moderate slope of index ≈−3.5. This result matches the opacity-corrected distribution observed at z = 0 surprisingly well. The cosmological mass density of neutral gas in DLAs is found to be \hbox{$\omegagdla \approx 10^{-3}$}ΩgDLA≈10-3, evolving only mildly over the past 12 billion years.
We study the effect of filter zero-point uncertainties on future supernova dark energy missions. Fitting for calibration parameters using simultaneous analysis of all Type Ia supernova standard ...candles achieves a significant improvement over more traditional fit methods. This conclusion is robust under diverse experimental configurations (number of observed supernovae, maximum survey redshift, inclusion of additional systematics). This approach to supernova fitting considerably eases otherwise stringent mission calibration requirements. As an example we simulate a space-based mission based on the proposed JDEM satellite; however the method and conclusions are general and valid for any future supernova dark energy mission, ground or space-based.
We present the Data Release 9 Quasar (DR9Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were ...targeted as quasar candidates during the survey, are spectrocopically confirmed as quasars via visual inspection, have luminosities Miz = 2 < −20.5 (in a ΛCDM cosmology with H0 = 70 km s-1 Mpc-1, ΩM = 0.3, and ΩΛ = 0.7) and either display at least one emission line with full width at half maximum (FWHM) larger than 500 km s-1 or, if not, have interesting/complex absorption features. It includes as well, known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. This catalog contains 87 822 quasars (78 086 are new discoveries) detected over 3275 deg2 with robust identification and redshift measured by a combination of principal component eigenspectra newly derived from a training set of 8632 spectra from SDSS-DR7. The number of quasars with z > 2.15 (61 931) is ~2.8 times larger than the number of z > 2.15 quasars previously known. Redshifts and FWHMs are provided for the strongest emission lines (C iv, C iii, Mg ii). The catalog identifies 7533 broad absorption line quasars and gives their characteristics. For each object the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3600−10 500 Å at a spectral resolution in the range 1300 < R < 2500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 949 quasars that have been identified, among galaxy targets of the BOSS or among quasar targets after DR9 was frozen.
SVX', the new CDF silicon vertex detector Azzi, P.; Bacchetta, N.; Barnett, B.A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1995, Letnik:
360, Številka:
1-2
Journal Article
Recenzirano
The Collider Detector at Fermilab (CDF) radiation hardened silicon vertex detector (SVX') is described. The new detector has several improvements over its predecessor such as better signal to noise ...and higher efficiency. It is expected to have a radiation tolerance in excess of 1 Mrad. It has been taking data for several months and some preliminary results are shown.
Design and performance tests of the CDF time-of-flight system Paus, Ch; Grozis, C.; Kephart, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2001, Letnik:
461, Številka:
1
Journal Article
Recenzirano
The CDF
II detector contains a time-of-flight detector consisting of 216 scintillator bars of 279
cm length and 4×4
cm
2 cross-section located at a radius of 138
cm from the beam axis. The bars are ...installed on the inner surface of the CDF solenoid, which produces an axial field of 1.4
T. Nineteen-stage fine-mesh photomultiplier tubes are attached at both ends of the scintillator bars. Photostatistics limit the time-of-flight resolution, which is expected to be 100
ps. The primary physics motivation is K
± identification for improved neutral B meson flavor determination.
This paper presents the Data Release 9 (DR9) Quasar catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS) III. The catalog identifies 7533 broad ...absorption line quasars and gives their characteristics. For each object the catalog presents five-band CCD-based photometry with typical accuracy of 0.03 mag, and information on the morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3600-10 500 ... at a spectral resolution in the range 1300 less than R less than 2500; the spectra can be retrieved from the SDSS Catalog Archive Server. The authors also provide a supplemental list of an additional 949 quasars that have been identified, among galaxy targets of the BOSS or among quasar targets after DR9 was frozen.(ProQuest: ... denotes formulae/symbols omitted.)
We present the first results from an ongoing survey for Damped Lyman-alpha systems (DLAs) in the spectra of z>2 quasars observed in the course of the Baryon Oscillation Spectroscopic Survey (BOSS), ...which is part of the Sloan Digital Sky Survey (SDSS) III. Our full (non-statistical) sample, based on Data Release 9, comprises 12,081 systems with log N(HI)>=20, out of which 6,839 have log N(HI)>=20.3. This is the largest DLA sample ever compiled, superseding that from SDSS-II by a factor of seven. Using a statistical sub-sample and estimating systematics from realistic mock data, we probe the N(HI) distribution at = 2.5. Contrary to what is generally believed, the distribution extends beyond 10^22 cm^-2 with a moderate slope of index\approx-3.5. This result matches surprisingly well the opacity-corrected distribution observed at z = 0. The cosmological mass density of neutral gas in DLAs is found to be Omega_g_DLA~10^-3, evolving only mildly over the past 12 billion years.
A full-custom CMOS integrated circuit for silicon strip detector systems has been designed, fabricated, and tested. The circuit contains 128 parallel data-acquisition channels and considerable ...peripheral circuitry. Each channel consists of a low-noise, low-power, charge-sensitive amplifier, a multistage autobalanced comparator, an analog multiplexer, nearest-neighbor logic, priority-search logic, and a share of a position-encoding read-only memory. The analog system can substract both detector pedestal and leakage current on a channel-by-channel basis. A key feature of this design is the inclusion of on-chip sparse read-out circuitry, which allows efficient management of low-occupancy events. Designed for use at the Collider Detector Facility (CDF) at Fermilab, the circuit is suitable for large-scale silicon detector systems requiring a large, dense array of fast, low-power electronics.< >
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