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Design, Fabrication, and Irradiation of Superheat Fuel Element SH-4B in VBWR

Description: From abstract: "The design, fabrication, and irradiation results are described for a 0.028 inch thick 304 stainless clad fuel element (SH-4B) exposed in the Vallecitos Boiling Water Reactor loop under superheat conditions."
Date: September 1, 1961
Creator: Spalaris, C. N.; Boyle, R. F.; Evans, T. F. & Esch, E. L.
Partner: UNT Libraries Government Documents Department

Solar Neutrino Physics

Description: With its heavy water target, the Sudbury Neutrino Observatory (SNO) offers the unique opportunity to measure both the 8B flux of electron neutrinos from the Sun and, independently, the flux of all active neutrino species reaching the Earth. A model-independent test of the hypothesis that neutrino oscillations are responsible for the observed solar neutrino deficit can be made by comparing the charged-current (CC) and neutral-current (NC) rates. This LDRD proposal supported the research and development necessary for an assessment of backgrounds and performance of the SNO detector and the ability to extract the NC/CC-Ratio. Particular emphasis is put upon the criteria for deployment and signal extraction from a discrete NC detector array based upon ultra-low background 3He proportional counters.
Date: July 15, 1999
Creator: Bowles, T.J.; Brice, S.J.; Esch, E.-I.; Fowler, M.M.; Goldschmidt, A.; Hime, A. et al.
Partner: UNT Libraries Government Documents Department

Progress on the Europium Neutron-Capture Study using DANCE

Description: The accurate measurement of neutron-capture cross sections of the Eu isotopes is important for many reasons including nuclear astrophysics and nuclear diagnostics. Neutron capture excitation functions of {sup 151,153}Eu targets were measured recently using a 4{pi} {gamma}-ray calorimeter array DANCE located at the Los Alamos Neutron Science Center for E{sub n} = 0.1-100 keV. The progress on the data analysis efforts is given in the present paper. The {gamma}-ray multiplicity distributions for the Eu targets and Be backing are significantly different. The {gamma}-ray multiplicity distribution is found to be the same for different neutron energies for both {sup 151}Eu and {sup 153}Eu. The statistical simulation to model the {gamma}-ray decay cascade is summarized.
Date: September 5, 2006
Creator: Agvaanluvsan, U; Becker, J A; Macri, R A; Parker, W; Wilk, P; Wu, C Y et al.
Partner: UNT Libraries Government Documents Department

Review of Livermore-Led Neutron Capture Studies Using DANCE

Description: We have made neutron capture cross-section measurements using the white neutron source at the Los Alamos Science Center, the DANCE detector array (Detector for Advanced Neutron Capture Experiments) and targets important for basic science and stockpile stewardship. In this paper, we review results from (n,{gamma}) reactions on {sup 94,95}Mo, {sup 152,154,157,160,nat}Gd, {sup 151,153}Eu and {sup 242m}Am for neutron energies from < 1eV up to {approx} 20 keV. We measured details of the {gamma}-ray cascade following neutron capture, for comparison with results of statistical model simulations. We determined the neutron energy dependent (n,{gamma}) cross section and gained information about statistical decay properties, including the nuclear level density and the photon strength function. Because of the high granularity of the detector array, it is possible to look at gamma cascades with a specified number of transitions (a specific multiplicity). We simulated {gamma}-ray cascades using a combination of the DICEBOX/GEANT computer codes. In the case of the deformed nuclei, we found evidence of a scissors-mode resonance. For the Eu, we also determined the (n,{gamma}) cross sections. For the {sup 94,95}Mo, we focused on the spin and parity assignments of the resonances and the determination of the photon strength functions for the compound nuclei {sup 95,96}Mo. Future plans include measurements on actinide targets; our immediate interest is in {sup 242m}Am.
Date: May 11, 2007
Creator: Parker, W; Sheets, S; Agvaanluvsan, U; Becker, J; Becvar, F; Bredeweg, T et al.
Partner: UNT Libraries Government Documents Department

The Radiative Strength Function Using the Neutron-Capture Reaction on 151,153Eu

Description: Radiative strength functions in {sup 152,154}Eu nuclei for {gamma}-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. Properties of resonances in these two nuclei are examined. The measurements are compared to simulation of cascades performed with various models for the radiative strength function. Comparison between experimental data and simulation suggests an existence of the low-energy resonance in these two nuclei.
Date: October 4, 2005
Creator: Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R et al.
Partner: UNT Libraries Government Documents Department

Investigation of the Statistical Properties of Stable Eu Nuclei using Neutron-Capture Reactions

Description: Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. The highly efficient DANCE (Detector for Advanced Neutron Capture Experiments) array coupled with the intense neutron beam at Los Alamos Neutron Science Center is used for the experiment. Stable Eu isotopes mass separated and electroplated on Be backings were used. Properties of well-resolved, strong resonances in two Eu nuclei are examined. The parameters for most of these resonances are known. Detailed multiplicity information for each resonance is obtained employing the high granularity of the DANCE array. The radiative decay cascades corresponding to each resonance are obtained in the experiment. The measurements are compared to simulation of these cascades which calculated with various models for the radiative strength function. Comparison between the experimental data and simulation provides an opportunity to investigate the average quantities.
Date: October 4, 2005
Creator: Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R et al.
Partner: UNT Libraries Government Documents Department

An array of low-background 3He proportional counters for theSudbury Neutrino Observatory

Description: An array of Neutral-Current Detectors (NCDs) has been builtin order to make a unique measurement of the total active ux of solarneutrinos in the Sudbury Neutrino Observatory (SNO). Data in the thirdphase of the SNO experiment were collected between November 2004 andNovember 2006, after the NCD array was added to improve theneutral-current sensitivity of the SNO detector. This array consisted of36 strings of proportional counters lled with a mixture of 3He and CF4gas capable of detecting the neutrons liberated by the neutrino-deuteronneutral current reaction in the D2O, and four strings lled with a mixtureof 4He and CF4 gas for background measurements. The proportional counterdiameter is 5 cm. The total deployed array length was 398 m. The SNO NCDarray is the lowest-radioactivity large array of proportional countersever produced. This article describes the design, construction,deployment, and characterization of the NCD array, discusses theelectronics and data acquisition system, and considers event signaturesand backgrounds.
Date: February 1, 2007
Creator: Amsbaugh, J.F.; Anaya, J.M.; Banar, J.; Bowles, T.J.; Browne,M.C.; Bullard, T.V. et al.
Partner: UNT Libraries Government Documents Department