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in creator/contributor: "Groom, D.E."

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Radiation levels in the SSC interaction regions

The radiation environment in a typical SSC detector has been evaluated using the best available particle production models coupled with Monte Carlo simulations of hadronic and electromagnetic cascades. The problems studied include direct charged particle dose, dose inside a calorimeter from the cascades produced by incident photons and hadrons, the flux of neutrons and photons backscattered from the calorimeter into a central cavity, and neutron flux in the calorimeter. The luminosity lifetime … more

Date: June 10, 1988

Creator: Groom, D.E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Recent progress on CCDs for astronomical imaging

We review recent progress in the field, using as a framework a partial list of present limitations and problems: CCD and mosaic size, packing fraction in mosaics, red response and fringing, and intrinsic point-spread function due to lateral charge diffusion. Related topics such as orthogonal-transfer CCDs and the special requirements of adaptive-optics wavefront sensors are also discussed. Only cursory attention is given to other relevant issues, such as readout speed and anti-blooming techniqu… more

Date: February 28, 2000

Creator: Groom, D.E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Incident Energy Dependence of Hadronic Activity

Two features of high-energy hadronic cascades have been long known to shielding specialists: (a) in a high-energy hadronic cascade in a given material (incident E {approx_equal} 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and (b) because {pi}{sup 0} production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron i… more

Date: March 1, 1993

Creator: Gabriel, T. A.; Groom, D. E.; Job, P. K.; Mokhov, N. V. & Stevenson, G. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Search for Single Photons From Radiative Neutrino or Supersymmetric Particle Production

Final results are presented from a search for single-photons produced in association with neutrinos or other weakly interacting neutral particles in e/sup +/e/sup -/ annihilations at ..sqrt..s = 29 GeV. The search was performed with the MAC detector at PEP in a total integrated luminosity of 177 pb/sup -1/. The search limits the number of light-neutrino families to N/sub nu/ < 16. The mass of the selectron is limited to m/sub e tilde/ > 50 GeV/c/sup 2/ if m/sub e tilde L/ = m/sub e tilde R/ and… more

Date: June 1, 1986

Creator: Ford, W. T.; Camporesi, T.; Hurst, R. B.; Band, H. R.; Ash, W. W.; Chadwick, G. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radiation Environment in the Tunnel of a High-Energy Proton Accelerator at Energies Near 1 TeV

Neutron energy spectra, fluence distributions and rates in the FNAL Tevatron tunnel are summarized. This work has application to radiation damage to electronics and research equipment at high energy accelerators, as well as to radiological protection. 7 refs., 4 figs.

Date: December 1987

Creator: McCaslin, J. B.; Sun, R. K. S.; Swanson, W. P.; Cossairt, J. D.; Elwyn, A. J.; Freeman, W. S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Point-spread function in depleted and partially depleted CCDs

The point spread function obtainable in an astronomical instrument using CCD readout is limited by a number of factors, among them the lateral diffusion of charge before it is collected in the potential wells. They study this problem both theoretically and experimentally, with emphasis on the thick CCDs on high-resistivity n-type substrates being developed at Lawrence Berkeley National Laboratory.

Date: October 13, 1999

Creator: Groom, D. E.; Eberhard, P. H.; Holland, S. E.; Levi, M. E.; Palaio, N. P.; Perlmutter, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radiation events in astronomical CCD images

The remarkable sensitivity of depleted silicon to ionizing radiation is a nuisance to astronomers. ''Cosmic rays'' degrade images because of struck pixels, leading to modified observing strategies and the development of algorithms to remove the unwanted artifacts. In the new-generation CCD's with thick sensitive regions, cosmic-ray muons make recognizable straight tracks and there is enhanced sensitivity to ambient gamma radiation via Compton-scattered electrons (''worms''). Beta emitters insid… more

Date: December 18, 2001

Creator: Smith, A. R.; McDonald, R. J.; Hurley, D. L.; Holland, S. E.; Groom, D. E.; Brown, W. E. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of Back-Illuminated, Fully-Depleted CCD Image Sensors for Use in Optical and Near-IR Astronomy

Charge-coupled devices (CCD's) of novel design have been fabricated at Lawrence Berkeley National Laboratory (LBNL), and the first large-format science-grade chips for astronomical imaging are now being characterized at Lick Observatory. They are made on 300-μm thick n-type high-resistivity (~10,000 Ω-cm) silicon wafers, using a technology developed at LBNL to fabricate low-leakage silicon microstrip detectors for high-energy physics. A bias voltage applied via a transparent contact on the back… more

Date: May 10, 1999

Creator: Groom, D. E.; Holland, S. E.; Levi, M. E.; Palaio, N. P.; Perlmutter,S.; Stover, R. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A measurement of E/. pi. for a fast lead liquid argon calorimeter

The NA34 (HELIOS) calorimeter has measured e/{pi} {congruent} 1.1 in a uranium/liquid argon calorimeter with a shaping time of 135 nsec. Lead may be a viable alternative, but e/{pi} must first be measured at fast shaping times in lead. We re preparing to measure e/{pi} at momenta ranging from 0.5 to 20 GeV/c and with shaping times of 50, 100 and 150 nsec.

Date: January 1, 1990

Creator: Makowiecki, D.; Gordon, H. A.; Ma, H.; Murtagh, M.; Radeka, V.; Rahm, D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Proton radiation damage in high-resistivity n-type silicon CCDs

A new type of p-channel CCD constructed on high-resistivity n-type silicon was exposed to 12 MeV protons at doses up to 1x1011 protons/cm2. The charge transfer efficiency was measured as a function of radiation dose and temperature. We previously reported that these CCDs are significantly more tolerant to radiation damage than conventional n-channel devices. In the work reported here, we used pocket pumping techniques and charge transfer efficiency measurements to determine the identity and con… more

Date: December 20, 2001

Creator: Bebek, C. J.; Groom, D. E.; Holland, S. E.; Karcher, A.; Kolbe, W. F.; Lee, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Incident energy dependence of hadronic activity

Two features of high-energy hadronic cascades have been long known to shielding specialists: (a) in a high-energy hadronic cascade in a given material (incident E [approx equal] 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and (b) because [pi][sup 0] production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron i… more

Date: January 1, 1993

Creator: Gabriel, T.A. (Oak Ridge National Lab., TN (United States)); Groom, D.E. (Lawrence Berkeley Lab., CA (United States)); Job, P.K. (Argonne National Lab., IL (United States)); Mokhov, N.V. (Institute of High Energy Physics, Serpukov (Russian Federation) Superconducting Super Collider Lab., Dallas, TX (United States)) & Stevenson, G.R. (European Organization for Nuclear Research, Geneva (Switzerland)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A Guide to Experimental Elementary Particle Physics Literature 1994-1998

No Description Available.

Date: October 1, 1999

Creator: Ezhela, V.; Filimonov, B. B.; Lugovsky, S. B.; Lugovsky, V. S.; Polishchuk, B. V.; Razuvaev, E. A. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The distant type Ia supernova rate

We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample,which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -… more

Date: May 20, 2002

Creator: Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R. S.; Aldering, G.; Astier, P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Timescale stretch parameterization of Type Ia supernova B-band light curves

R-band intensity measurements along the light curve of Type Ia supernovae discovered by the Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter the time-axis width factor w identically equal to s times (1+z). The data points are then individually aligned in the time-axis, normalized and K-corrected back to the rest frame, after which the nearly 1300 normalized intensity measurements are found to lie on a well-determined common rest-frame B-band curve which we… more

Date: April 1, 2001

Creator: Goldhaber, G.; Groom, D.E.; Kim, A.; Aldering, G.; Astier, P.; Conley, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Measurement of Omega_m, Omega_Lambda from a blind analysis of TypeIa supernovae with CMAGIC: Using color information to verify theacceleration of the Universe

We present measurements of {Omega}{sub m} and {Omega}{sub {Lambda}} from a blind analysis of 21 high redshift supernovae using a new technique (CMAGIC) for fitting the multicolor lightcurves of Type Ia supernovae, first introduced in Wang et al. (2003). CMAGIC takes advantage of the remarkably simple behavior of Type Ia supernovae on color-magnitude diagrams, and has several advantages over current techniques based on maximum magnitudes. Among these are a reduced sensitivity to host galaxy dust… more

Date: February 21, 2006

Creator: Conley, A.; Goldhaber, G.; Wang, L.; Aldering, G.; Amanullah, R.; Commins, E. D. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A measurement of E/{pi} for a fast lead liquid argon calorimeter

Date: December 31, 1990

Creator: Makowiecki, D.; Gordon, H. A.; Ma, H.; Murtagh, M.; Radeka, V.; Rahm, D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Spectra of High-Redshift Type Ia Supernovae and a Comparison withtheir Low-Redshift Counterparts

We present spectra for 14 high-redshift (0.17 < z < 0.83) supernovae, which were discovered by the Supernova Cosmology Project as part of a campaign to measure cosmological parameters. The spectra are used to determine the redshift and classify the supernova type, essential information if the supernovae are to be used for cosmological studies. Redshifts were derived either from the spectrum of the host galaxy or from the spectrum of the supernova itself. We present evidence that these sup… more

Date: July 20, 2005

Creator: Hook, I. M.; Howell, D. A.; Aldering, G.; Amanullah, R.; Burns, M. S.; Conley, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Restframe I-band Hubble diagram for type Ia supernovae up toredshift z ~; 0.5

We present a novel technique for fitting rest frame I-bandlight curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z {approx} 0.5 yields results consistent with a flat Lambda-dominated ''concordance universe'' (OmegaM,Omega Lambda) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also use… more

Date: April 1, 2005

Creator: Nobili, S.; Amanullah, R.; Garavini, G.; Goobar, A.; Lidman, C.; Stanishev, V. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra… more

Date: March 24, 2008

Creator: Supernova Cosmology Project

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spectroscopic Observations and Analysis of the Unusual Type Ia SN1999ac

The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the … more

Date: July 12, 2005

Creator: Garavini, G.; Aldering, G.; Amadon, A.; Amanullah, R.; Astier, P.; Balland, C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department