93 Matching Results

Search Results

Results: 1 - 24 next
open access

Free-Electron Lasers: Present Status and Future Prospects

Description: Free-electron lasers as scientific instruments are reviewed. The present status and future prospects are delineated with attention drawn to the size, complexity, availability, and performance capability of this new tool. The Free-Electron Laser (FEL) was proposed by John Madey in 1970 (1), although earlier work, relevant to the concept, had been performed by Motz (2) and by Phillips (3). Experimental demonstration was achieved by Madey, et. al. in 1975 and 1976 (4). Since that time, FELs of div… more
Date: May 1, 1990
Creator: Kim, K. J. & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department
open access

Calibration and performance of the MARK II drift chamber vertex detector

Description: We have calibrated and studied the performance of the MARK II drift chamber vertex detector with cosmic ray tracks collected with the chamber inside the MARK II detector at the SLC. The chamber achieves 30 {mu}m impact parameter resolution and 500 {mu}m track-pair resolution using CO{sub 2}/C{sub 2}H{sub 6}H{sub 6}(92/8) at 2 atmospheres pressure. The chamber has successfully recorded Z{sup 0} decays at the SLC, and resolved tracks in dense hadronic jets with good efficiency and high accuracy. … more
Date: May 1, 1990
Creator: Durrett, D.; Ford, W. T.; Hinshaw, D. A.; Rankin, P.; Smith, J. G.; Weber, P. et al.
Partner: UNT Libraries Government Documents Department
open access

Proton rapidity distributions from 60 GeV/n sup 16 O+Au collisions

Description: An analysis of the proton rapidity distribution in central {sup 16}O+Au collisions at 60 GeV/n measured in the NA35 streamer chamber detector at the CERN SPS is presented. The charge excess of positive particles over negative particles was measured. The rapidity distribution of the charge excess which can be associated with the primordial protons in the collision is studied in terms of the nuclear stopping power and is compared to the predictions of various models. 7 refs., 2 figs.
Date: May 1, 1990
Creator: Baechler, J.; Hoffman, M.; Runge, K.; Schmoetten, E. (Freiburg Univ. (Germany, F.R.). Fakultaet fuer Physik); Bartke, J.; Gladysz, E. (Institute of Nuclear Physics, Cracow (Poland)) et al.
Partner: UNT Libraries Government Documents Department
open access

Gamma-ray induced displacement in D20 reactors

Description: Gamma-ray damage to tank walls is typically more severe in D{sub 2}O than in H{sub 2}O moderated lattices because of the much higher ratios of slow-to-fast neutron flux. To estimate this effect it was first necessary to develop energy dependent gamma-ray displacement cross sections for iron. These, along with coupled neutron-gamma-ray transport computations, provided a measure of displacement damage from this source in SRS reactor tank walls. Gamma-ray displacements originating from high energy… more
Date: May 1, 1990
Creator: Baumann, N.P.
Partner: UNT Libraries Government Documents Department
open access

Mechanistic Understanding of Irradiation-Induced Corrosion of Zirconium Alloys in Nuclear Power Plants: Stimuli, Status, and Outlook

Description: Failures in the basic materials used in nuclear power plants continue to be costly and insidious, despite increasing industry vigilance to catch failures before they degrade safety. For instance, the overall costs to the US industry from materials problems could amount to as much as $10 billion annually. Moreover, estimates indicate that the cost of a pipe failure in a nuclear plant is one hundred times greater than the cost of a similar failure in a coal-fired plant. There are important practi… more
Date: May 1, 1990
Creator: Johnson, A. B., (Jr.); Ishigure, K.; Nechaev, A. F.; Reznichenko, E. A.; Cox, B.; Lemaignan, C. et al.
Partner: UNT Libraries Government Documents Department
open access

Metal Cation/Anion Adsorption on Calcium Carbonate: Implications to Metal Ion Concentrations in Groundwater

Description: This chapter evaluates the sorption behavior of metallic ions on specimen calcite as a basis for determining the importance of calcite relative to other subsurface sorbents, such as layer silicates and oxides, in controlling metal ion concentration in calcareous groundwaters. A review of the literature shows the sorption of both metallic cations and anions on calcite over ranges in pH and CO{sub 2} partial pressure to be consistent with a surface-exchange process where cations exchange with sur… more
Date: May 1, 1990
Creator: Zachara, J. M.; Cowan, C. E. & Resch, C. T.
Partner: UNT Libraries Government Documents Department
open access

Automatic tracking of the intersection of a laser and electron beam

Description: For the Compton Polarimeter experiment at the Stanford Linear Accelerator the crossing point of a laser beam and an electron beam must be kept accurate and stable. An electronic system is described for the automatic tracking and correcting of the beam crossing. A remote CCD camera, relatively insensitive to electromagnetic disturbance, records small displacements of the pulsed laser beam. Video signals are analyzed at a remote station, the amount of drift from a selected reference point determi… more
Date: May 1, 1990
Creator: Turko, B.T.; Fuzesy, R.Z.; Pripstein, D.A.; Kowitt, M.; Chamberlain, O.; Shapiro, G. (Lawrence Berkeley Lab., CA (USA)) et al.
Partner: UNT Libraries Government Documents Department
open access

Superdeformed bands in sup 194 Tl

Description: Superdeformation was first observed in the mass-190 region in {sup 191}Hg. Since then, SD bands have been found in {sup 190-194}Hg nuclei. Here we report the discovery of two such bands in {sup 194}Tl which are the first SD bands fond in this mass region that are not in Hg nuclei. Subsequently, bands have been found in two Pb nuclei. 5 refs., 1 fig.
Date: May 1, 1990
Creator: Azaiez, F.; Kelly, W. H.; Korten, W.; Deleplanque, M. A.; Stephens, F. S.; Diamond, R. M. et al.
Partner: UNT Libraries Government Documents Department
open access

Large P sub t jets at CDF

Description: The inclusive jet cross section and the dijet mass spectrum have been measured at the Fermilab Tevatron Collider at {radical}s = 1.8 TeV. These measurements span approximately 7 orders of magnitude in cross section and contain jets up to 400 GeV in transverse energy and dijet masses up to 950 GeV. Comparisons have been made to QCD at both orders {alpha}{sub s}{sup 2} and {alpha}{sub s}{sup 3}. 8 refs., 9 figs.
Date: May 9, 1990
Creator: Dell'Orso, M. (Pisa Univ. (Italy). Dipt. di Fisica)
Partner: UNT Libraries Government Documents Department
open access

Whole-Pin Furnace system: An experimental facility for studying irradiated fuel pin behavior under potential reactor accident conditions

Description: The whole-pin furnace system is a new in-cell experimental facility constructed to investigate how irradiated fuel pins may fail under potential reactor accident conditions. Extensive checkouts have demonstrated excellent performance in remote operation, temperature control, pin breach detection, and fission gas handling. The system is currently being used in testing of EBIR-II-irradiated Integral Fast Reactor (IFR) metal fuel pins; future testing will include EBR-II-irradiated mixed-oxide fuel… more
Date: May 1, 1990
Creator: Liu, Y. Y.; Tsai, H. C.; Donahue, D. A.; Pushis, D. O.; Savoie, F. E.; Holland, J. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Electron cyclotron current drive experiments on DIII-D

Description: Electron Cyclotron Current Drive (ECCD) experiments on the DIII-D tokamak have been performed using 60 GHz waves launched from the high field side of the torus. Preliminary analysis indicates rf driven currents between 50 and 100 kA in discharges with total plasma currents between 200 and 500 kA. These are the first ECCD experiments with strong first pass absorption, localized deposition of the rf power, and {tau}{sub E} much longer than the slowing-down time of the rf generated current carrier… more
Date: May 1, 1990
Creator: James, R. A.; Giruzzi, G.; de Gentile, B.; Rodriguez, L.; Fyaretdinov, A.; Gorelov, Yu. et al.
Partner: UNT Libraries Government Documents Department
open access

Top quark and SUSY (supersymmetric) searches at CDF

Description: Searches for the top quark in p{bar p} collisions at {radical}s = 1.8 TeV are described. The analyses are based on data with an integrated luminosity of 4.4 pb{sup {minus}1} recorded with the Collider Detector at Fermilab in the 1988--1989 run. An upper limit on the t{bar t} cross section is obtained. The top quark with mass below 89 GeV/c{sup 2} is excluded at the 95% CL. Prospects for searches for the top quark in the future are presented. We also briefly present results on searches for super… more
Date: May 17, 1990
Creator: Yeh, G.P.
Partner: UNT Libraries Government Documents Department
open access

Three-Family Top Quark Mass Spectrum

Description: We expand upon our previous Monte-Carlo-type study of 3-family mass matrices which lead to the experimentally-determined KM matrix and satisfy the constraints imposed by B{sub d}--{bar B}{sub d} mixing, {vert bar}V{sub ub}/V{sub cb}{vert bar}, B{sub K} and CP violation. Scatter distributions in {vert bar}V{sub ub}V{sub cb}{vert bar}, {epsilon}{prime}/{epsilon} and x{sub s} vs m{sub t} are presented for the standard minimal Higgs structure as well as top quark mass histograms for the minimal and… more
Date: May 1990
Creator: Albright, Carl H.
Partner: UNT Libraries Government Documents Department
open access

Fast excitation wiggler development

Description: The design of an easily stackable, variable period length, fast excitation driven wiggler, making use of geometrically alternating substacks of Vanadium Permandur ferromagnetic laminations, interspaced with conductive, non magnetic, material laminations which act as eddy current induced field reflectors,'' is discussed and experimental results obtained with short wiggler models are presented. 7 refs., 13 figs.
Date: May 1, 1990
Creator: van Steenbergen, A.; Gallardo, J.; Romano, T. & Woodle, M.
Partner: UNT Libraries Government Documents Department
open access

Neural network tutorial for high energy physicists

Description: Neural Networks are introduced through analogies to data analysis and electronic techniques used in high energy physics. 18 refs., 11 figs.
Date: May 1, 1990
Creator: Denby, B.
Partner: UNT Libraries Government Documents Department
open access

US-Japan workshop on field-reversed configurations with steady-state high-temperature fusion plasmas and the 11th US-Japan workshop on compact toroids

Description: The US-Japan Workshop on Field-Reversed Configurations with Steady-State High-Temperature Fusion Plasma and the 11th US-Japan Workshop on Compact Toroids were held at Los Alamos National Laboratory, Los Alamos, New Mexico on November 7--9, 1989. These proceedings contain the papers presented at the workshops as submitted by the authors. These papers have been indexed separately.
Date: May 1, 1990
Creator: Barnes, D. C.; Fernandez, J. C. & Rej, D. J. (comps.)
Partner: UNT Libraries Government Documents Department
open access

A Fast Online Event Display for a High Intensity Fixed-Target Spectrometer

Description: A workstation-based event display program for the Fermilab Tagged Photon Spectrometer (TPS) is described. Fast displays are required to monitor detector elements, observe hit patterns and energy deposition, and to check track reconstruction. Design considerations, novel features, and performance are designed. 5 refs., 4 figs., 1 tab.
Date: May 3, 1990
Creator: Napier, Austin
Partner: UNT Libraries Government Documents Department
open access

Physics with polarization at the SLD

Description: The SLD detector is nearing completion and will start physics-quality data-taking at the SLC in 1991 with a longitudinally polarized electron beam and unpolarized positron beam. The current status of the detector is reviewed and the rich program of physics measurements possible with polarization and the SLD detector is briefly presented. In particular, the left-right polarization asymmetry, A{sub LR}, will be a unique measurement for the next few years and will allow tight bounds to be set upon… more
Date: May 1, 1990
Creator: Burrows, P.N. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Lab. for Nuclear Science)
Partner: UNT Libraries Government Documents Department
open access

Phase gradients in acceleration structures

Description: In linear accelerators with two or more bunches the beam loading of one bunch will influence the energy and energy spread the following bunches. This can be corrected by quickly changing the phase of a travelling wave structure, so that each bunch recieves a slightly different net phase. At the SLAC Linear Collider (SLC) three bunches, two (e{sup +},e{sup {minus}}) for the high energy collisions and one (e{sup {minus}}-scavenger) for producing positrons should sit at different phases, due to th… more
Date: May 1, 1990
Creator: Decker, F.J. & Jobe, R.K.
Partner: UNT Libraries Government Documents Department
open access

An updated summary of MATHEW/ADPIC model evaluation studies

Description: This paper summarizes the major model evaluation studies conducted for the MATHEW/ADPIC atmospheric transport and diffusion models used by the US Department of Energy's Atmospheric Release Advisory Capability. These studies have taken place over the last 15 years and involve field tracer releases influenced by a variety of meteorological and topographical conditions. Neutrally buoyant tracers released both as surface and elevated point sources, as well as material dispersed by explosive, therma… more
Date: May 1, 1990
Creator: Foster, Kevin T. & Dickerson, Marvin H.
Partner: UNT Libraries Government Documents Department
open access

Atmospheric modeling in complex terrain

Description: Los Alamos investigators have developed several models which are relevant to modeling Mexico City air quality. The collection of models includes: meteorological models, dispersion models, air chemistry models, and visibility models. The models have been applied in several different contexts. They have been developed primarily to address the complexities posed by complex terrain. HOTMAC is the meteorological model which requires terrain and limited meteorological information. HOTMAC incorporates… more
Date: May 1, 1990
Creator: Williams, M. D. & Streit, G. E.
Partner: UNT Libraries Government Documents Department
open access

Gamma heating measurements with proportional counters

Description: A new data acquisition technique (the Continuously-varied Bias- voltage Acquisition mode) has been developed and tested for the low-flux broad-energy regime characteristic of existing fusion blanket mock-ups. This method of analysis allows for the acquisition of data spanning several orders of magnitude in energy with a single proportional counter. Utilizing this method, the gamma energy deposition in a mixed neutron and gamma field was measured. 7 refs., 5 figs.
Date: May 1, 1990
Creator: Chiu, H.; Bennett, E.F. & Micklich, B.J.
Partner: UNT Libraries Government Documents Department
open access

IGORR-1: Proceedings of the first meeting of the international group on research reactors

Description: Many organizations, in several countries, are planning or implementing new or upgraded research reactor projects, but there has been no organized forum devoted entirely to discussion and exchange of information in this field. Over the past year or so, informal discussions resulted in widespread agreement that such a forum would serve a useful purpose. Accordingly, a proposal to form a group was submitted to the leading organizations known to be involved in projects to build or upgrade reactor f… more
Date: May 1, 1990
Creator: West, C.D. (comp.)
Partner: UNT Libraries Government Documents Department
open access

Angular Momentum in Subbarrier Fusion

Description: We have measured the ratio of the isomer to ground-state yields of {sup 137}Ce produced in the fusion reactions {sup 128}Te({sup 12}C,3n), {sup 133}Cs({sup 7}Li,3n), {sup 136}Ba({sup 3}He,2n), {sup 136}Ba({sup 4}He,3n), and {sup 137}Ba({sup 3}He,3n), from energies above the Coulomb barrier to energies typically 20--30% below the barrier by observing the delayed x- and {gamma}-ray emission. We deduce the average angular momentum, {lt}J{gt}, from the measured isomer ratios with a statistical mode… more
Date: May 1, 1990
Creator: DiGregorio, D. E.; Lesko, K. T.; Harmon, B. A.; Norman, E. B.; Pouliot, J.; Sur, B. et al.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen