An updated measurement of sin (2{Beta}) at CDF (open access)

An updated measurement of sin (2{Beta}) at CDF

We report an updated direct measurement of the Standard Model CP violation parameter sin(2{beta}) using the CDF Detector at Fermilab. We use the entire Run-I data sample of 110 pb{sup -1} of proton-antiproton collisions at {radical}s = 1.8 TeV. In this analysis, we have combined three tagging methods: a same-side tag, a soft-lepton tag, and a jet-charge tag, and also added events that have less precise lifetime information because they are not fully contained within the acceptance of the SVX. The signal sample consists of {approx} 400 B {yields} J/{psi} K{sub S}{sup 0} events. A maximum likelihood fitting method is used to measure sin(2{beta}) = 0.79{sub -0.44}{sup +0.41} (stat.+syst.). We calculate a 93% Feldman-Cousins confidence interval of 0 < sin(2{beta}) < 1. This measurement is the best direct indication for CP violation in the neutral B meson sector to date. The sin(2{beta}) value is consistent with the Standard Model prediction of large CP symmetry violation in the b quark system.
Date: November 5, 1999
Creator: Bedeschi, Franco
Object Type: Article
System: The UNT Digital Library
Reactor Materials Program - Baseline Material Property Handbook - Mechanical Properties of 1950's Vintage Stainless Steel Weldment Components, Task Number 89-23-A-1 (open access)

Reactor Materials Program - Baseline Material Property Handbook - Mechanical Properties of 1950's Vintage Stainless Steel Weldment Components, Task Number 89-23-A-1

The Process Water System (primary coolant) piping of the nuclear production reactors constructed in the 1950''s at Savannah River Site is comprised primarily of Type 304 stainless steel with Type 308 stainless steel weld filler. A program to measure the mechanical properties of archival PWS piping and weld materials (having approximately six years of service at temperatures between 25 and 100 degrees C) has been completed. The results from the mechanical testing has been synthesized to provide a mechanical properties database for structural analyses of the SRS piping.
Date: November 5, 1999
Creator: Stoner, K. J.
Object Type: Report
System: The UNT Digital Library
Protocols and standard crate configuration for a typical CDF Run 2 readout crate (open access)

Protocols and standard crate configuration for a typical CDF Run 2 readout crate

This paper describes a standard for the readout and the trigger interface of a VMEbus based crate to be used by the front-end and trigger electronics of the CDF Run 2 experiment. Hereafter, this crate will be referred to as the CDF Readout Crate. The goal is to standardize the implementation of functions that are common among all systems (i.e. power distribution, timing signals, DAQ functions) while allowing some flexibility with other functions (e.g. cooling, rear transition modules, J3 backplanes, etc.). This allows designers of cards that satisfy this standard to have access to a common well defined crate system with interfaces to the trigger and DAQ system, allowing them to concentrate their efforts on the functions they need. This paper lists the mechanical specifications, readout scheme, backplane and signal distribution specifications of the CDF Readout Crate. The paper will also go into some detail on the TRigger And Clock + Event Readout (TRACER) module, a common CDF crate module which provides the crate interface to the system clock and the trigger system.
Date: November 5, 1999
Creator: al., Theresa Shaw et
Object Type: Article
System: The UNT Digital Library
Borel Summation and Momentum-Plane Analyticity in Perturbative QCD (open access)

Borel Summation and Momentum-Plane Analyticity in Perturbative QCD

We derive a compact expression for the Borel sum of a QCD amplitude in terms of the inverse Mellin transform of the corresponding Borel function. The result allows us to investigate the momentum-plane analyticity properties of the Borel-summed Green functions in perturbative QCD. An interesting connection between the asymptotic behavior of the Borel transform and the Landau singularities in the momentum plane is established. We consider for illustration the polarization function of massless quarks and the resummation of one-loop renormalon chains in the large-{beta}{sub 0} limit, but our conclusions have a more general validity.
Date: February 5, 1999
Creator: Neubert, Matthias
Object Type: Report
System: The UNT Digital Library
Effects of Beamtube Roughness on X-Ray FEL Performance (open access)

Effects of Beamtube Roughness on X-Ray FEL Performance

In an X-Ray FEL like the Linear Coherent Light Source (LCLS) being designed at SLAC, electron bunches about 70 {micro}m FWHM long are sent into a beam tube only 5 mm in internal diameter and more than 100 m in length. Due to the surface roughness of the beam tube, wakefields can be generated that catch up to the bunch and interact with it, causing energy spread and emittance growth. The strength of this effect depends on the details of the roughness of the surface. We present here a study in which the roughness of the beam tube was measured, and the longitudinal impedance of the tube was calculated. Our result shows that commercially available beam tube can be made smooth enough so the resulting wakefield effects are within the tolerance determined by the requirement that the induced relative energy spread of the beam be less then 5 x 10{sup {minus}4}.
Date: April 5, 1999
Creator: Stupakov, Gennady
Object Type: Report
System: The UNT Digital Library
Ion Beam Sputter Fabrication of Micro-Grooving and Micro-Threading Tools (open access)

Ion Beam Sputter Fabrication of Micro-Grooving and Micro-Threading Tools

This paper presents techniques for fabricating microscopic, nonplanar features in a variety of materials. Micro-grooving and micro-threading tools having cutting dimensions of 10-30{micro}m are made by focused ion beam sputtering and used in ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide. This creates cutting edges having radii of curvature less than 0.4 {micro}m, and rake features similar to conventional lathe tools. Clearance for minimizing frictional drag of a tool results from the sputter yield dependence on ion herd target incidence angle. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close matching between tool width and feature size. Microtools controllably machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061-T6 Al cylindrical substrates. Micro-grooving tools also fabricate sinusoidal waveform features in polished metal substrates.
Date: November 5, 1999
Creator: Adams,David P.; Vasile,M. J. & Krishnan,A. S. M.
Object Type: Article
System: The UNT Digital Library
Hypersonic ground test capabilities for T and E testing above mach 8 ''a case where S and T meets T and E'' (open access)

Hypersonic ground test capabilities for T and E testing above mach 8 ''a case where S and T meets T and E''

Simulation of hypersonic flight in ground test and evaluation (T and E) facilities is a challenging and formidable task, especially to fully duplicate the flight environment above approximately Mach 8 for most all hypersonic flight systems that have been developed, conceived, or envisioned. Basically, and for many years, the enabling technology to build such a ground test wind tunnel facility has been severely limited in the area of high-temperature, high-strength materials and thermal protection approaches. To circumvent the problems, various approaches have been used, including partial simulation and use of similarity laws and reduced test time. These approaches often are not satisfactory, i.e. operability and durability testing for air-breathing propulsion development and thermal protection development of many flight systems. Thus, there is a strong need for science and technology (S and T) community involvement in technology development to address these problems. This paper discusses a specific case where this need exists and where significant S and T involvement has made and continues to make significant contributions. The case discussed will be an Air Force research program currently underway to develop enabling technologies for a Mach 8-15 hypersonic true temperature wind tunnel with relatively long run time. The research is based …
Date: October 5, 1999
Creator: Constantino, M.; Miles, R.; Brown, G.; Laster, M. & Nelson, G.
Object Type: Article
System: The UNT Digital Library
Laser Assisted Plasma Arc Welding (open access)

Laser Assisted Plasma Arc Welding

Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.
Date: October 5, 1999
Creator: Fuerschbach, Phillip W.
Object Type: Article
System: The UNT Digital Library
Lifetime studies of Mo/Si and Mo/Be multilayer coatings for extreme ultraviolet lithography (open access)

Lifetime studies of Mo/Si and Mo/Be multilayer coatings for extreme ultraviolet lithography

Extreme Ultraviolet Lithography (EUVL) is a candidate for future application by the semiconductor industry in the production of sub-100 nm feature sizes in integrated circuits. Using multilayer reflective coatings optimized at wavelengths ranging from 11 to 14 nm, EUVL represents a potential successor to currently existing optical lithography techniques. In order to assess lifetimes of the multilayer coatings under realistic conditions, a series of radiation stability tests has been performed. In each run a dose of EUV radiation equivalent to several months of lithographic operation was applied to Mo/Si and MO/Be multilayer coatings within a few days. Depending on the residual gas concentration in the vacuum environment, surface deposition of carbon during the exposure lead to losses in the multilayer reflectivity. However, in none of the experimental runs was structural damage within the bulk of the multilayers observed. Mo/Si multilayer coatings recovered their full original reflectivity after removal of the carbon layer by an ozone cleaning method. Auger depth profiling on MO/Be multilayers indicate that carbon penetrated into the Be top layer during illumination with high doses of EUV radiation. Subsequent ozone cleaning fully removed the carbon, but revealed enhanced oxidation of the area illuminated, which led to an irreversible …
Date: August 5, 1999
Creator: Bajt, S; Clift, W M; Folta, J A; Gullikson, E M; Klebanoff, L E; Kleineberg, U et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of Crystalline Silicotitanate and Self-Assembled Monolayers on Mesoporous Support for Cesium and Mercury Removal from DWPF Recycle (open access)

Evaluation of Crystalline Silicotitanate and Self-Assembled Monolayers on Mesoporous Support for Cesium and Mercury Removal from DWPF Recycle

The affinities for cesium and mercury ions contained in DWPF recycle simulants and Tank-22H waste have been evaluated using Crystalline Silicotitanate (CST) and Self-Assembled Monolayers on Mesoporous Support (SAMMS) ion-exchange materials, respectively. Results of the performance evaluations of CST on the uptake of cesium with simulants and actual DWPF recycle samples (Tank 22H) indicate that, in practice, this inorganic ion-exchange material can be used to remove radioactive cesium from the DWPF recycle. SAMMS material showed little or no affinity for mercury from highly alkaline DWPF waste. However, at near neutral conditions (DWPF simulant solution pH adjusted to 7), SAMMS was found to have a significant affinity for mercury. Conventional Duolite/256 ion exchange material showed an increase in affinity for mercury with increase in DWPF recycle simulant pH. Duolite/256 GT-73 also had a high batch distribution coefficient for mercury uptake from actual Tank 22H waste.
Date: November 5, 1999
Creator: Oji, L.N.
Object Type: Report
System: The UNT Digital Library
Single top and top properties at CDF (open access)

Single top and top properties at CDF

Recent CDF results with 110 pb{sup -1} of data on top quark production and decay properties are presented. Limits are placed on single top quark production in the W* and W-gluon channels. A measurement of the polarization of the intermediate W boson in top decay, a search for resonances in the mass of the t{bar t} system, and the transverse momentum of top quarks in t{bar t} events are presented.
Date: November 5, 1999
Creator: Koehn, P.
Object Type: Article
System: The UNT Digital Library
Brittle-Ductile Relaxation Kinetics of Strained AlGaN/GaN (open access)

Brittle-Ductile Relaxation Kinetics of Strained AlGaN/GaN

The authors have directly measured the stress evolution during metal organic chemical vapor deposition of AlGaN/GaN heterostructures on sapphire. In situ stress measurements were correlated with ex situ microstructural analysis to directly determine a critical thickness for cracking and the subsequent relaxation kinetics of tensile-strained Al{sub x}Ga{sub 1{minus}x}N on GaN. Cracks appear to initiate the formation of misfit dislocations at the AlGaN/GaN interface, which account for the majority of the strain relaxation.
Date: October 5, 1999
Creator: CHASON, E.; FLORO, JERROLD A.; FOLLSTAEDT, DAVID M.; HAN, JUNG; HEARNE, SEAN JOSEPH; LEE, STEPHEN R. et al.
Object Type: Article
System: The UNT Digital Library
Y-12 Uranium Exposure Study (open access)

Y-12 Uranium Exposure Study

Following the recent restart of operations at the Y-12 Plant, the Radiological Control Organization (RCO) observed that the enriched uranium exposures appeared to involve insoluble rather than soluble uranium that presumably characterized most earlier Y-12 operations. These observations necessitated changes in the bioassay program, particularly the need for routine fecal sampling. In addition, it was not reasonable to interpret the bioassay data using metabolic parameter values established during earlier Y-12 operations. Thus, the recent urinary and fecal bioassay data were interpreted using the default guidance in Publication 54 of the International Commission on Radiological Protection (ICRP); that is, inhalation of Class Y uranium with an activity median aerodynamic diameter (AMAD) of 1 {micro}m. Faced with apparently new workplace conditions, these actions were appropriate and ensured a cautionary approach to worker protection. As additional bioassay data were accumulated, it became apparent that the data were not consistent with Publication 54. Therefore, this study was undertaken to examine the situation.
Date: August 5, 1999
Creator: Eckerman, K. F. & Kerr, G. D.
Object Type: Report
System: The UNT Digital Library
SMQIE: A charge integrator and encoder chip for the CDF Run II Shower Max Detector (open access)

SMQIE: A charge integrator and encoder chip for the CDF Run II Shower Max Detector

The Technical Design Report for the CDF II Detector calls for the development of an imbedded two-dimensional position sensitive detector sandwiched inside the electromagnetic calorimeter and placed at the shower maximum. The purpose of this detector is to aid in the identification of electrons and photons, to separate photons from {pi}{sup 0}s, and to help identify electromagnetic showers. This detector is called the Shower Max. In order to achieve CDF's goals for resolution, timing, power and economy, as well as to fit into the available space, a full-custom integrated circuit was required for the project - the SMQIE. The SMQIE has been fabricated in a 1.2{micro}m CMOS process using vertical NPN transistors in critical areas. It operates without deadtime. Its QIEs have eight ranges and an overall dynamic range of 13 bits. Its FADCs have a 5-bit resolution with a nominal LSB of 31.25 mV. Its Level 1 Trigger delays are 42 beam crossings or approximately 5.5 {micro}s. Its data buffers hold up to four events, each of which can consist of four time slices. Finally, the chip accepts a maximum input charge up to 150 pC with a minimum resolution of 15 fC.
Date: November 5, 1999
Creator: al., J. Hoff et
Object Type: Article
System: The UNT Digital Library
Qualitative Macroinvertebrate Assessment of Crouch Branch, June 1999 (open access)

Qualitative Macroinvertebrate Assessment of Crouch Branch, June 1999

An assessment of the macroinvertebrate community of Crouch Branch was performed in June 1999 to determine if effluent from the H-02 outfall is impairing the quality of the stream. Concurrent samples were collected for metals analyses (copper and zinc). The results of the study indicate that the stream is most impaired just downstream from the H-02 outfall and that the quality of the stream biota improves with increasing distance from the outfall. Conversely, macroinvertebrate habitat quality is best just downstream from the H-02 outfall. The midreaches of the stream contain very poor habitat quality, and the lower reaches of the stream, contain habitat of intermediate quality. Although much of the stream has degraded habitat due to channel erosion and scouring, there is strong evidence to suggest that the impairment is due to elevated concentrations of copper and zinc that are present in the H-02 effluent. A comparison of macroinvertebrate data collected in 1997 to the data collected in this study indicates that the macroinvertebrate community of Crouch Branch has improved markedly in the last two years.
Date: November 5, 1999
Creator: Specht, Winona L.
Object Type: Report
System: The UNT Digital Library
A/M Area Metallurgical Laboratory: Summary of Phase I Characterization Well Installation, Cone Penetrometer Testing and Soil Coring for Soil Headspace Analysis (open access)

A/M Area Metallurgical Laboratory: Summary of Phase I Characterization Well Installation, Cone Penetrometer Testing and Soil Coring for Soil Headspace Analysis

This report documents the Phase I characterization of chlorinated solvent contamination in the regulatory-defined uppermost aquifer (includes the M Area, Lost Lake and middle sand aquifer zones) within the Metallurgical Laboratory (Met Lab) of the A/M Area.
Date: November 5, 1999
Creator: Van Pelt, R.S.
Object Type: Report
System: The UNT Digital Library
System architecture and hardware design of the CDF XFT online track processor (open access)

System architecture and hardware design of the CDF XFT online track processor

A trigger track processor is being designed for CDF Run 2. This processor identifies high momentum (P{sub T} > 1.5 GeV/c) charged tracks in the new central outer tracking chamber for the CDF II detector. The design of the track processor, called the eXtremely Fast Tracker (XFT), is highly parallel and handle an input rate of 183 Gbits/sec and output rate of 44 Gbits/sec. The XFT is pipelined and reports the results for a new event every 132ns. The XFT uses three stages, hit classification, segment finding, and segment linking. The pattern recognition algorithms for the three stages are implemented in Programmable Logic Devices (PLDs) which allow for in-situ modification of the algorithm at any time. The PLDs reside on three different types of modules. Prototypes of each of these modules have been designed and built, and are working. An overview of the hardware design and the system architecture are presented.
Date: November 5, 1999
Creator: al., Scott Holm et
Object Type: Article
System: The UNT Digital Library
The Effects of Damage on Hydrogen-Implant-Induced Thin-Film Separation from Bulk Silicon Carbide (open access)

The Effects of Damage on Hydrogen-Implant-Induced Thin-Film Separation from Bulk Silicon Carbide

Exfoliation of Sic by hydrogen implantation and subsequent annealing forms the basis for a thin-film separation process which, when combined with hydrophilic wafer bonding, can be exploited to produce silicon-carbide-on-insulator, SiCOI. Sic thin films produced by this process exhibit unacceptably high resistivity because defects generated by the implant neutralize electrical carriers. Separation occurs because of chemical interaction of hydrogen with dangling bonds within microvoids created by the implant, and physical stresses due to gas-pressure effects during post-implant anneal. Experimental results show that exfoliation of Sic is dependent upon the concentration of implanted hydrogen, but the damage generated by the implant approaches a point when exfoliation is, in fact, retarded. This is attributed to excessive damage at the projected range of the implant which inhibits physical processes of implant-induced cleaving. Damage is controlled independently of hydrogen dosage by elevating the temperature of the SiC during implant in order to promote dynamic annealing. The resulting decrease in damage is thought to promote growth of micro-cracks which form a continuous cleave. Channeled H{sup +} implantation enhances the cleaving process while simultaneously minimizing residual damage within the separated film. It is shown that high-temperature irradiation and channeling each reduces the hydrogen fluence required to …
Date: April 5, 1999
Creator: Gregory, R. B.; Holland, O. W.; Thomas, D. K.; Wetteroth, T. A. & Wilson, S. R.
Object Type: Article
System: The UNT Digital Library
Magnetic Exchange-Coupling in CoPt/Co Bilayer Thin Films (open access)

Magnetic Exchange-Coupling in CoPt/Co Bilayer Thin Films

Thin film CoPt/Co bilayers have been prepared as a model system to investigate the relationship between microstructure and exchange coupling in two-phase hard/soft composite magnets. CoPt films, with a thickness of 25 nm, were sputter-deposited from a nearly equiatomic alloy target onto oxidized Si wafers. The films were subsequently annealed at 700 C and fully transformed from the FCC phase to the magnetically hard, ordered L1{sub 0} phase. The coercivity of the films increased rapidly with annealing time until it reached a plateau at approximately 9.5 kOe. Fully-ordered CoPt films were then used as substrates for deposition of Co layers, with thicknesses in the range of 2.8--225 nm, in order to produce the hard/soft composite bilayers. As predicted by theory, the magnetic coherency between the soft Co phase and the hard, ordered CoPt phase decreased as the thickness of the soft phase increased. This decrease in coupling was clearly seen in the magnetic hysteresis loops of the bilayers. At small thicknesses of Co (a few nanometers), the shape of the loop was one of a uniform material showing no indication of the presence of two phases with extremely different coercivities. At larger Co thicknesses, constricted loops, i.e., ones showing the …
Date: April 5, 1999
Creator: Kim, J.; Barmak, K.; Lewis, L. H.; Crew, D. C. & Welch, D. O.
Object Type: Article
System: The UNT Digital Library
The Regional Water Table of the Savannah River Site and Related Coverages (open access)

The Regional Water Table of the Savannah River Site and Related Coverages

A new regional-scale map of the water table configuration beneath the Savannah River Site and its surrounding area has been developed. This map is regarded as a more accurate representation of this surface than all previous maps.
Date: January 5, 1999
Creator: Hiergesell, R.A.
Object Type: Report
System: The UNT Digital Library
Nonlinear Amplitude Evolution During Spontaneous Patterning of Ion-Bombarded Si(001) (open access)

Nonlinear Amplitude Evolution During Spontaneous Patterning of Ion-Bombarded Si(001)

The time evolution of the amplitude of periodic nanoscale ripple patterns formed on Ar+ sputtered Si(OOl ) surfaces was examined using a recently developed in situ spectroscopic technique. At sufficiently long times, we find that the amplitude does not continue to grow exponentially as predicted by the standard Bradley-Harper sputter rippling model. In accounting for this discrepancy, we rule out effects related to the concentration of mobile species, high surface curvature, surface energy anisotropy, and ion-surface interactions. We observe that for all wavelengths the amplitude ceases to grow when the width of the topmost terrace of the ripples is reduced to approximately 25 nm. This observation suggests that a short circuit relaxation mechanism limits amplitude . growth. A strategy for influencing the ultimate ripple amplitude is discussed.
Date: May 5, 1999
Creator: Chason, Eric; Erlebacher, Jonah, Aziz, Michael J.; Floro, Jerold A. & Sinclair, Michael B.
Object Type: Article
System: The UNT Digital Library
Residence times of fine tropospheric aerosols as determined by {sup 210}Pb progeny. (open access)

Residence times of fine tropospheric aerosols as determined by {sup 210}Pb progeny.

Fine tropospheric aerosols can play important roles in the radiative balance of the atmosphere. The fine aerosols can act directly to cool the atmosphere by scattering incoming solar radiation, as well as indirectly by serving as cloud condensation nuclei. Fine aerosols, particularly carbonaceous soots, can also warm the atmosphere by absorbing incoming solar radiation. In addition, aerosols smaller than 2.5 {micro}m have recently been implicated in the health effects of air pollution. Aerosol-active radioisotopes are ideal tracers for the study of atmospheric transport processes. The source terms of these radioisotopes are relatively well known, and they are removed from the atmosphere only by radioactive decay or by wet or dry deposition of the host aerosol. The progeny of the primordial radionuclide {sup 238}U are of particular importance to atmospheric studies. Uranium-238 is common throughout Earth's crust and decays to the inert gas {sup 222}Rn, which escapes into the atmosphere. Radon-222 decays by the series of alpha and beta emissions shown in Figure 1 to the long-lived {sup 210}Pb. Once formed, {sup 210}Pb becomes attached to aerosol particles with average attachment times of 40 s to 3 min.
Date: October 5, 1999
Creator: Marley, N. A.; Gaffney, J. S.; Drayton, P. J.; Cunningham, M. M.; Mielcarek, C.; Ravelo, R. et al.
Object Type: Article
System: The UNT Digital Library
Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner (open access)

Test Plan for Radioactive Testing of a Vertical Direct Denitration Calciner

A vertical calciner will be used to demonstrate the direct denitration process for converting plutonium-bearing liquors to stable plutonium rich solids. The calciner and some of its associated equipment were previously tested with non-radioactive chemicals to demonstrate operability.
Date: October 5, 1999
Creator: Compton, J. A.
Object Type: Report
System: The UNT Digital Library
Recent Developments in the Design of the NLC Positron Source (open access)

Recent Developments in the Design of the NLC Positron Source

Recent developments in the design of the Next Linear Collider (NLC) positron source based on updated beam parameters are described. The unpolarized NLC positron source [1,2] consists of a dedicated 6.2 GeV S-band electron accelerator, a high-Z positron production target, a capture system and an L-band positron linac. The 1998 failure of the SLC target, which is currently under investigation, may lead to a variation of the target design. Progress towards a polarized positron source is also presented. A moderately polarized positron beam colliding with a highly polarized electron beam results in an effective polarization large enough to explore new physics at NLC. One of the schemes towards a polarized positron source incorporates a polarized electron source, a 50 MeV electron accelerator, a thin target for positron production and a new capture system optimized for high-energy, small angular-divergence positrons. The yield for such a process, checked using the EGS4 code, is of the order of 10{sup -3}. The EGS4 code has being enhanced to include the effect of polarization in bremsstrahlung and pair-production process.
Date: November 5, 1999
Creator: Kotseroglou, T.; Bharadwaj, V.; Clendenin, J. E.; Ecklund, S,; Frisch, J.; Krejcik, P. et al.
Object Type: Article
System: The UNT Digital Library