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Cross sections required for FMIT dosimetry

Description: The Fusion Materials Irradiation Test (FMIT) facility, currently under construction, is designed to produce a high flux of high energy neutrons for irradiation effects experiments on fusion reactor materials. Characterization of the flux-fluence-spectrum in this rapidly varying neutron field requires adaptation and extension of currently available dosimetry techniques. This characterization will be carried out by a combination of active, passive, and calculational dosimetry. The goal is to provide the experimenter with accurate neutron flux-fluence-spectra at all positions in the test cell. Plans have been completed for a number of experimental dosimetry stations and provision for these facilities has been incorporated into the FMIT design. Overall needs of the FMIT irradiation damage program delineate goal accuracies for dosimetry that, in turn, create new requirements for high energy neutron cross section data. Recommendations based on these needs have been derived for required cross section data and accuracies.
Date: May 2, 1980
Creator: Gold, R.; McElroy, W.N.; Lippincott, E.P.; Mann, F.M.; Oberg, D.L.; Roberts, J.H. et al.
Partner: UNT Libraries Government Documents Department

Grasers: proposals, problems, and prospects

Description: The possibility and potentiality of amplification of recoilless radiation emitted by nuclear isomers has long been recognized; nevertheless, development of gamma-ray lasers continues to await resolution of the pumping vs. linebreadth dilemma. Problems that accompany proposals for reducing the excitation requirements and suggest areas of investigation that may contribute to resolving the dilemma are identified; several involve use of optical lasers.
Date: January 1, 1982
Creator: Baldwin, G.C.
Partner: UNT Libraries Government Documents Department

A nuclear cross section data handbook

Description: Isotopic information, reaction data, data availability, heating numbers, and evaluation information are given for 129 neutron cross-section evaluations, which are the source of the default cross sections for the Monte Carlo code MCNP. Additionally, pie diagrams for each nuclide displaying the percent contribution of a given reaction to the total cross section are given at 14 MeV, 1 MeV, and thermal energy. Other information about the evaluations and their availability in continuous-energy, discrete-reaction, and multigroup forms is provided. The evaluations come from ENDF/B-V, ENDL85, and the Los Alamos Applied Nuclear Science Group T-2. Graphs of all neutron and photon production cross-section reactions for these nuclides have been categorized and plotted. 21 refs., 5 tabs.
Date: December 1, 1989
Creator: Fisher, H.O.M.
Partner: UNT Libraries Government Documents Department

ACDOS1: a computer code to calculate dose rates from neutron activation of neutral beamlines and other fusion-reactor components

Description: A computer code has been written to calculate neutron induced activation of neutral-beam injector components and the corresponding dose rates as a function of geometry, component composition, and time after shutdown. The code, ACDOS1, was written in FORTRAN IV to calculate both activity and dose rates for up to 30 target nuclides and 50 neutron groups. Sufficient versatility has also been incorporated into the code to make it applicable to a variety of general activation problems due to neutrons of energy less than 20 MeV.
Date: August 1, 1981
Creator: Keney, G.S.
Partner: UNT Libraries Government Documents Department

ENDF/B summary documentation

Description: This publication provides a localized source of descriptions for the evaluations contained in the ENDF/B Library. The summary documentation presented is intended to be a more detailed description than the (File 1) comments contained in the computer readable data files, but not so detailed as the formal reports describing each ENDF/B evaluation. The summary documentations were written by the CSEWB (Cross Section Evaluation Working Group) evaluators and compiled by NNDC (National Nuclear Data Center). This edition includes documentation for materials found on ENDF/B Version V tapes 501 to 516 (General Purpose File) excluding tape 504. ENDF/B-V also includes tapes containing partial evaluations for the Special Purpose Actinide (521, 522), Dosimetry (531), Activation (532), Gas Production (533), and Fission Product (541-546) files. The materials found on these tapes are documented elsewhere. Some of the evaluation descriptions in this report contain cross sections or energy level information. (RWR)
Date: July 1, 1979
Creator: Kinsey, R. (comp.)
Partner: UNT Libraries Government Documents Department

Compilation of requests for nuclear data

Description: The purpose of this compilation is to summarize the current needs of US Nuclear Energy programs and other applied technologies for nuclear data. At the present time needs fall primarily in the area of neutron cross sections, although no such limitation is intended. This request list is ordered by target nucleus (isotope) and then reaction type (quantity). An attempt is made to describe the quantity in standard notation. A glossary of these symbols with a short explanatory text is provided. All requests must give the energy (or range of energy) for the incident particle when appropriate. The accuracy needed in percent is also given. The error quoted is assumed to be 1 sigma at each measured point in the energy range requested unless a comment specifies otherwise. (RWR)
Date: April 1, 1979
Partner: UNT Libraries Government Documents Department

Report to the DOE Nuclear Data Committee, 1984

Description: Experimental results are discussed for: /sup 6/ /sup 7/Li(n,/sup 4/He) cross sections at 14 MeV, neutron elastic and inelastic scattering from carbon near 14 MeV, neutron capture cross sections for /sup 46/Ca and /sup 48/Ca at stellar temperatures, revised neutron cross sections for /sup 142/ /sup 143/ /sup 144/Nd, fragment angular distribution for neutron fission of /sup 232/Th, neutron differential scattering measurements in the actinide region, nuclear structure of /sup 244/Am, conversion coefficients of the M4 transition in /sup 193m/Ir, gamma-ray and conversion-electron decay of the /sup 238/U shape isomer, and levels of /sup 244/Cm populated by the beta decay of 10-hr /sup 244g/Am and 26-minute /sup 244m/Am. Calculations described include tests of microscopic optical models for neutron and proton scattering on light nuclei in the range 14 to 45 MeV, a new dynamic model for fission, and the necessity of discrete-level modeling in isomer ratio calculations for neutron-induced reactions on deformed nuclei. Also, a reevaluation for ENDL of sigma(n,f) and anti nu p for /sup 235/U and /sup 239/Pu from 100 keV to 20 MeV is described. 31 references. (WHK)
Date: February 1, 1984
Creator: Wong, C.; Haight, R.C. & Struble, G.L.
Partner: UNT Libraries Government Documents Department

Some nuclear data needs in astrophysics

Description: In this paper we discuss a number of astrophysical environments and how improved nuclear data could facilitate a better understanding of them. One area of interest includes proton and alpha-particle reactions with unstable nuclei which are necessary for understanding the nucleosynthesis and energy generation in hot hydrogen-burning environments. Efforts underway at LLNL and elsewhere to develop the technology for the measurement of these reaction rates are discussed. Heavy-element nucleosynthesis in the late stages of red-giant stars and supernovae requires a complete network of neutron capture rates and beta-decay rates for nuclei near and far from stability. Experimental and theoretical efforts at LLNL to supply the input data and to model the nucleosynthetic environments will be outlined. Suggestions are made as to which nuclear data are most critical for the various scenarios. 42 refs., 11 figs., 1 tab.
Date: May 1, 1985
Creator: Mathews, G.J.; Bauer, R.W.; Bloom, S.D.; Haight, R.C.; Howard, W.M.; Takahashi, K. et al.
Partner: UNT Libraries Government Documents Department

Some comments on resolution and the analysis and interpretation of experimental results from differential neutron measurements

Description: Effects of finite resolution in differential neutron measurements are examined. General procedures for deriving the experimental resolution functions from a knowledge of the experimental parameters are presented. Problems encountered in the comparison of different data sets, when the measured cross section is known to fluctuate with energy, are discussed. The objective is to encourage closer attention to the matter of resolution by experimenters, evaluators and users of neutron nuclear data.
Date: November 1, 1979
Creator: Smith, D.L.
Partner: UNT Libraries Government Documents Department

Neutron strength functions: the link between resolved resonances and the optical model

Description: Neutron strength functions and scattering radii are useful as energy and channel radius independent parameters that characterize neutron scattering resonances and provide a connection between R-matrix resonance analysis and the optical model. The choice of R-matrix channel radii is discussed, as are limitations on the accuracies of strength functions. New definitions of the p-wave strength function and scattering radius are proposed. For light nuclei, where strength functions display optical model energy variations over the resolved resonances, a doubly reduced partial neutron width is introduced for more meaningful statistical analyses of widths. The systematic behavior of strength functions and scattering radii is discussed.
Date: January 1, 1980
Creator: Moldauer, P.A.
Partner: UNT Libraries Government Documents Department

Simultaneous evaluation of interrelated cross sections by generalized least-squares and related data file requirements

Description: Though several cross sections have been designated as standards, they are not basic units and are interrelated by ratio measurements. Moreover, as such interactions as /sup 6/Li + n and /sup 10/B + n involve only two and three cross sections respectively, total cross section data become useful for the evaluation process. The problem can be resolved by a simultaneous evaluation of the available absolute and shape data for cross sections, ratios, sums, and average cross sections by generalized least-squares. A data file is required for such evaluation which contains the originally measured quantities and their uncertainty components. Establishing such a file is a substantial task because data were frequently reported as absolute cross sections where ratios were measured without sufficient information on which reference cross section and which normalization were utilized. Reporting of uncertainties is often missing or incomplete. The requirements for data reporting will be discussed.
Date: October 25, 1984
Creator: Poenitz, W.P.
Partner: UNT Libraries Government Documents Department

University of Minnesota progress report No. 4215

Description: Medium-energy nuclear physics research at the University of Minnesota is reviewed. The following studies were undertaken: HRS development; /sup 58/ /sup 60/ /sup 62/ /sup 64/Ni(p,p') at 800 MeV; proton scattering on 2s-1d-shell nuclei; search for orbit flip states in /sup 90/Zr, /sup 120/Sn, /sup 144/Sm, and /sup 208/Pb; large-angle A/sup 116/ /sup 124/Sn, /sup 208/Pb elastic scattering; proton scattering from heavy deformed nuclei; unnatural-parity states in /sup 6/Li, /sup 10/B, /sup 12/C, /sup 14/N, and /sup 28/Si; microscopic form factor calculations - force studies; DEC PDP 11/60 computer; theoretical analysis computer programs; inelastic electron scattering on /sup 90/Zr; and EPICS programs. Three of the above topics, with significant amounts of data, are indexed separately. 40 figures, 1 table. (RWR)
Date: January 1, 1979
Creator: Hintz, N.M.
Partner: UNT Libraries Government Documents Department

Neutron scattering studies in the actinide region

Description: During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on {sup 14}N, {sup 181}Ta, {sup 232}Th, {sup 238}U and {sup 239}Pu; Prompt fission spectra for {sup 232}Th, {sup 235}U, {sup 238}U and {sup 239}Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus.
Date: August 1, 1991
Creator: Beghian, L.E. & Kegel, G.H.R.
Partner: UNT Libraries Government Documents Department

Standard reference and other important nuclear data by the Cross Section Evaluation Working Group

Description: This report is a current review of the status of standard reference and other important nuclear data pointing out data discrepancies, recommending new measurements, and comparing the current version of ENDF/B with data. Neutron reactions with /sup 1/H, /sup 3/H, /sup 6/Li, /sup 10/B, /sup 12/C, /sup 59/Co, /sup 80/Kr, /sup 136/Xe, /sup 153/Eu, and /sup 197/Au are included, along with reaction and other data for the actinide nuclei. Cross sections, spectra, etc., are given for some of the nuclides considered. (RWR)
Date: December 1, 1979
Partner: UNT Libraries Government Documents Department

North Carolina State University nuclear structure research at the Triangle Universities Nuclear Laboratory. Progress report, 1 April 1979-31 March 1980. [4/1/79 to 3/31/80]

Description: Research during the period April 1, 1979 to March 31, 1980 is reported in the following areas: neutron cross section experiments, high-resolution studies, radiative capture reactions, atomic physics, and nuclear theory and phenomenology. Other activities, including accelerator development and instrumentation and developments related to computers, are also sketched. The body of this report is a photocopy of that portion of the TUNL Annual Report XVIII in which NCSU personnel were involved. The TUNL Annual Report XVIII (see DOE/TIC--11133 in the Report Number Index) is indexed in greater depth. (RWR)
Date: February 1, 1980
Creator: Gould, C.R.; Mitchell, G.E.; Seagondollar, L.W. & Tilley, D.R.
Partner: UNT Libraries Government Documents Department

R-matrix analysis of the /sup 235/U neutron cross sections

Description: The ENDFB-V representation of the /sup 235/U neutron cross sections in the resolved resonance region is unsatisfactory: below 1 eV the cross sections are given by ''smooth files'' (file 3) rather than by resonance parameters; above 1 eV the single-level formalism used by ENDFB-V necessitates a structured file 3 contribution consisting of more than 1300 energy points; furthermore, information on level-spins has not been included. Indeed the ENDFB-V /sup 235/U resonance region is based on an analysis done in 1970 for ENDFB-III and therefore does not include the results of high quality measurements done in the past 18 years. The present paper presents the result of an R-matrix multilevel analysis of recent measurements as well as older data. The analysis also extends the resolved resonance region from its ENDFB-V upper limit of 81 eV to 110 eV. 13 refs., 2 figs., 1 tab
Date: January 1, 1988
Creator: Leal, L.C.; de Saussure, G. & Perez, R.B.
Partner: UNT Libraries Government Documents Department

Comparison of collimation systems for small-angle neutron scattering

Description: It is shown by simple first-order geometric arguments that for a given resolution, the flux on sample in a small-angle scattering instrument is independent of the form of the collimator or of the length of the instrument. Count rate may be increased by increasing the sample size, through the use of multi-aperture systems. In second order, it is shown to be advantageous to place the beam defining elements as close as possible to the source and the sample. The multiple-pinhole system gives maximum flux on small samples but has non-uniform illumination so that intensity increases only about half as fast as sample area. Soller slits and continuous tubes from source to sample were also considered, but neutron scattering and reflection from surfaces generate a large halo. Monte-Carlo simulations confirm these results, with the conclusion that the optimum collimator configuration is the multiple-pinhole system. 4 refs., 4 figs.
Date: January 1, 1985
Creator: Seeger, P.A.
Partner: UNT Libraries Government Documents Department

Nuclear data relevant to shield design of FMIT facility

Description: Nuclear data requirements are reviewed for the design of the Fusion Materials Irradiation Test (FMIT) facility. This accelerator-based facility, now in the early stages of construction at Hanford, will provide high fluences in a fusion-like radiation environment for the testing of materials. The nuclear data base required encompasses the entire range of neutron energies from thermal to 50 MeV. In this review, we consider neutron source terms, cross sections for thermal and bulk shield design, and neutron activation for the facility.
Date: April 1, 1980
Creator: Carter, L.L.; Morford, R.J. & Wilcox, A.D.
Partner: UNT Libraries Government Documents Department

Charge exchange probes of nuclear structure and interactions with emphasis on (p,n)

Description: New results from (p,n) studies at IUCF show that it is possible to observe Gamow-Teller (GT) strength and extract GT matrix elements from (p,n) measurements. The charge exchange reactions (/sup 6/Li,/sup 6/He) and (..pi../sup +/,..pi../sup 0/) involve different projectile quantum numbers, and the relationships of these reactions to (p,n) is discussed.
Date: January 1, 1980
Creator: Goodman, C.D.
Partner: UNT Libraries Government Documents Department

Inclusive charged-particle production in neutron-nucleus collisions. [Cross sections, rapidity dependence]

Description: Inclusive particle production was measured in neutron-nucleus collisions at high energies. Data on positive and negative particles produced in nuclei, ranging in size from Be to Pb, are presented for essentially the full forward hemisphere of the center of mass. Fits of the form A/sup ..cap alpha../ to the invariant production cross section indicate that ..cap alpha.. changes from approx. 0.85 to approx. 0.55 for laboratory rapidities ranging from 3 to 8. This result is consistent with predictions from multiperipheral models which invoke cut contributions to production in nuclei.
Date: January 1, 1977
Creator: Chaney, D.; Bleser, E. & Ferbel, T.
Partner: UNT Libraries Government Documents Department

An integrated system for production of neutrons and photonics calculational constants. Volume 15, Part A. The LLL Evaluated Nuclear Data Library (ENDL): evaluation techniques, reaction index, and descriptions of individual evaluations

Description: A general description of evaluation methods, a reaction index to evaluated data, and detailed descriptions of evaluated nuclear data for eighty-four isotopes or elements are presented.
Date: September 1, 1975
Creator: Howerton, R. J.; Cullen, D. E.; Haight, R. C.; MacGregor, M. H.; Perkins, S. T. & Plechaty, E. F.
Partner: UNT Libraries Government Documents Department