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Overview of the SuperNova/Acceleration probe (SNAP)

Description: The SuperNova/Acceleration Probe (SNAP) is a space-based experiment to measure the expansion history of the Universe and study both its dark energy and the dark matter. The experiment is motivated by the startling discovery that the expansion of the Universe is accelerating. A 0.7 square-degree imager comprised of 36 large format fully-depleted n-type CCD's sharing a focal plane with 36 HgCdTe detectors forms the heart of SNAP, allowing discovery and lightcurve measurements simultaneously for m… more
Date: July 29, 2002
Creator: galdering@lbl.gov
Partner: UNT Libraries Government Documents Department
open access

SNAP Telescope

Description: The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter class telescope delivering diffraction limited images spanning a one degree field in the visible and near infrared wavelength regime. This requirement, equivalent to nearly one billion pixel resolution, places stringent demands on its optical system in terms of field flatness, image quality, and freedom from chromatic aberration. We discuss the advantages of annular-field three-mirror anastigmat (TMA) telescopes for applic… more
Date: July 29, 2002
Creator: Lampton, Michael L.; Akerlof, C. W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E. et al.
Partner: UNT Libraries Government Documents Department
open access

A corrected and generalized successive random additions algorithm for simulating fractional levy motions

Description: Simulation of subsurface heterogeneity is important for modeling subsurface flow and transport processes. Previous studies have indicated that subsurface property variations can often be characterized by fractional Brownian motion (fBm) or (truncated) fractional Levy motion (fLm). Because Levy-stable distributions have many novel and often unfamiliar properties, studies on generating fLm distributions are rare in the literature. In this study, we generalize a relatively simple and computational… more
Date: May 29, 2002
Creator: Liu, Hui-Hai; Bodvarsson, Gudmundur S.; Lu, Silong & Molz, Fred J.
Partner: UNT Libraries Government Documents Department
open access

Surface structural analysis of LiF(100) thin films grown on Pt(111)

Description: The surface structure of a multilayer LiF(100) thin film grown on Pt(111) from the vapor has been determined by the automated tensor low energy electron diffraction (LEED) method. The final structure, which refined to a Pendry R-factor (RP) of 0.24, had a surface corrugation (D1) of 0.24+-0.04 Angstrom due to the Li+ being displaced towards the bulk, leaving the initially coplanar F - unshifted. A similar intralayer corrugation due to the movement of the Li+ was also observed in the layer immed… more
Date: August 29, 2002
Creator: Roberts, J.G.; Van Hove, M.A. & Somorjai, G.A.
Partner: UNT Libraries Government Documents Department
open access

Microscopic probabilistic model for the simulation of secondary electron emission

Description: We provide a detailed description of a model and its computational algorithm for the secondary electron emission process. The model is based on a broad phenomenological fit to data for the secondary emission yield (SEY) and the emitted-energy spectrum. We provide two sets of values for the parameters by fitting our model to two particular data sets, one for copper and the other one for stainless steel.
Date: July 29, 2002
Creator: Furman, M. A. & Pivi, M. T. F.
Partner: UNT Libraries Government Documents Department
open access

Overview of the nearby supernova factory

Description: The Nearby Supernova Factory (SNfactory) is an international experiment designed to lay the foundation for the next generation of cosmology experiments (such as CFHTLS, wP, SNAP and LSST) which will measure the expansion history of the Universe using Type Ia supernovae. The SNfactory will discover and obtain frequent lightcurve spectrophotometry covering 3200-10000 {angstrom} for roughly 300 Type Ia supernovae at the low-redshift end of the smooth Hubble flow. The quantity, quality, breadth of … more
Date: July 29, 2002
Creator: Aldering, Greg; Adam, Gilles; Antilogus, Pierre; Astier, Pierre; Bacon, Roland; Bongard, S. et al.
Partner: UNT Libraries Government Documents Department
open access

High resolution XPS study of oxide layers grown on Ge substrates

Description: High resolution X-ray Photoelectron Spectroscopy (XPS) was used to analyze thin layers of germanium oxide grown on germanium substrates under various conditions. The results reveal the presence of high density of electron states located at the oxide/germanium interface that lead to the energy band bending. The surface of native oxide layers and that of thin oxide layer grown under dry oxygen correspond to GeO2 composition. Under Ar etching, lower oxidation states were revealed. Short in-situ he… more
Date: July 29, 2002
Creator: Tabet, N.; Faiz, M.; Hamdan, N.M. & Hussain, Z.
Partner: UNT Libraries Government Documents Department
open access

Probing the gateway to superheavy nuclei in cranked relativistic Hartree-Bogoliubov theory.

Description: The cranked relativistic Hartree+Bogoliubov theory has been applied for a systematic study of the nuclei around {sup 264}No, the heaviest nuclei for which detailed spectroscopic data are available. The deformation, rotational response, pairing correlations, quasi-particle and other properties of these nuclei have been studied with different relativistic mean field (RMF) parametrizations. For the first time, the quasi-particle spectra of odd deformed nuclei have been calculated in a fully self-c… more
Date: August 29, 2002
Creator: Afanasjev, A. V.; Khoo, T. L.; Frauendorf, S.; Lalazissis, G. A. & Ahmad, I.
Partner: UNT Libraries Government Documents Department
open access

Heavy-ion linac development for the U.S. RIA project.

Description: The Nuclear Science Community in the Unites States has unanimously concluded that developments in both nuclear science and its supporting technologies make building a world-leading Rare-Isotope Accelerator (RIA) facility for production of radioactive beams the top priority. The RIA development effort involves several US Laboratories (ANL, JLAB, LBNL, MSU, ORNL). The RIA Facility includes a CW 1.4 GeV driver linac and a 100 MV post-accelerator both based on superconducting (SC) cavities operatin… more
Date: January 29, 2002
Creator: Ostroumov, P. N.
Partner: UNT Libraries Government Documents Department
open access

The influence of pre-irradiation heat treatments on thermal non-equilibrium and radiation-induced segregation behavior in model austenitic stainless steel alloys.

Description: The effect of pre-irradiation heat treatments on thermal non-equilibrium grain boundary segregation (TNES) and subsequent radiation-induced grain boundary segregation (RIS) is studied in a series of model austenitic stainless steels. The alloys used for this study are based on AISI 316 stainless steel and have the following nominal compositions: Fe-16Cr-13Ni-1.25Mn (base 316), Fe-16Cr-13Ni-1.25Mn-2.0Mo (316 + Mo) and Fe-16Cr-13Ni-1.25Mn-2.0Mo-0.07P (316 + Mo + P). Samples were heat treated at t… more
Date: July 29, 2002
Creator: Cole, J. I.; Allen, T. R.; Was, G. S.; Dropek, R. B. & Kenik, E. A.
Partner: UNT Libraries Government Documents Department
open access

Probing the phase diagram of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+delta} with tunneling spectroscopy.

Description: Tunneling measurements are performed on Ca-rich single crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi2212), with various oxygen doping levels, using a novel point contact method. At 4.2 K, SIN and SIS tunnel junctions are obtained with well-defined quasi-particle peaks, robust dip and hump features and in some cases Josephson currents. The doping dependence of tunneling conductances of Ca-rich Bi2212 are analyzed and compared to stoichiometric Bi2212. A similar profile of energy … more
Date: August 29, 2002
Creator: Ozyuzer, L.; Zasadzinski, J. F.; Gray, K. E.; Hinks, D. G. & Miyakawa, N.
Partner: UNT Libraries Government Documents Department
open access

Design of 57.5 MHz cw RFQ structure for the rare isotope accelerator facility.

Description: The Rare Isotope Accelerator (RIA) facility includes a driver linac for production of 400 kW CW heavy-ion beams. The initial acceleration of heavy-ions delivered from an ECR ion source can be effectively performed by a 57.5 MHz four-meter long RFQ. The principal specifications of the RFQ are: (1) formation of extremely low longitudinal emittance; (2) stable operation over a wide range of voltage for acceleration of various ion species needed for RIA operation; (3) simultaneous acceleration of t… more
Date: January 29, 2002
Creator: Ostroumov, P. N.; Kolomiets, A. A.; Kashinsky, D. A.; Minaev, S. A.; Pershin, V. I.; Yaramishev, S. G. et al.
Partner: UNT Libraries Government Documents Department
open access

Jet physics at the Tevatron

Description: Recent analyses by the CDF and D0 Collaborations of jet data produced in p{bar p} collisions at the Fermilab Tevatron Collider are presented. These include new studies of the inclusive jet production cross section, a measurement of the strong coupling constant, the first measurement of subjet multiplicity of quark and gluon jets, examination of ratios of multijet cross sections and their implications for choice of renormalization scale, and a study of charged jet evolution and energy flow in th… more
Date: May 29, 2002
Creator: Seidel, S.
Partner: UNT Libraries Government Documents Department
open access

Testing and operation of the WR340 waveguide window in the APS linac.

Description: The Advanced Photon Source (APS) linac high-power switching system makes extensive use of SF6 pressurized, WR340-size waveguide, incorporating waveguide switches. A tunable, extra low return loss waveguide window has been developed to support interfacing the pressurized waveguide with the original waveguide, which is under vacuum. The tunable approach is able to consistently achieve a return loss of at least 40 dB. Test and alignment methods, performance, and initial operating experience are de… more
Date: August 29, 2002
Creator: Gerlick, A. E.; Berg, S.; Goeppner, G. A.; Nassiri, A.; Pile, G. & Smith, T. L.
Partner: UNT Libraries Government Documents Department
open access

SNAP Near Infrared Detectors

Description: The SuperNova/Acceleration Probe (SNAP) will measure precisely the cosmological expansion history over both the acceleration and deceleration epochs and thereby constrain the nature of the dark energy that dominates our universe today. The SNAP focal plane contains equal areas of optical CCDs and NIR sensors and an integral field spectrograph. Having over 150 million pixels and a field-of-view of 0.34 square degrees, the SNAP NIR system will be the largest yet constructed. With sensitivity in t… more
Date: July 29, 2002
Creator: Tarle, G.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E. et al.
Partner: UNT Libraries Government Documents Department
open access

Recent CDF and D0 Run I results

Description: We summarize some of the most recent CDF and D0 results from the 1992-1995 collider run at the Fermilab Tevatron. These include a detailed examination of the heavy flavor content of W+jet data made by CDF. We found in this study that the rate and the kinematic properties of the event subsample, featuring soft lepton and secondary vertex in the same jet, are statistically difficult to accommodate with the Standard Model simulation. CDF has also searched for new physics in events with a photon, a… more
Date: May 29, 2002
Creator: Velev, G.
Partner: UNT Libraries Government Documents Department
open access

Transiting Topological Sectors With the Overlap

Description: The overlap operator provides an elegant definition for the winding number of lattice gauge field configurations. Only for a set of configurations of measure zero is this procedure undefined. Without restrictions on the lattice fields, however, the space of gauge fields is simply connected. I present a simple low dimensional illustration of how the eigenvalues of a truncated overlap operator flow as one travels between different topological sectors.
Date: June 29, 2002
Creator: Creutz, M.
Partner: UNT Libraries Government Documents Department
open access

Electron-cloud updated simulation results for the PSR, and recent results for the SNS

Description: Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code.
Date: May 29, 2002
Creator: Pivi, M. & Furman, M. A.
Partner: UNT Libraries Government Documents Department
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