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Neutron total cross section measurements in the energy region from 47 keV to 20 MeV

Description: Neutron total cross sections were measured for 26 elements. Data were obtained in the energy range from 47 keV to 20 MeV for 11 elements in the range of light-mass fission products. Previously reported measurements for eight heavy and actinide isotopes were extended to 20 MeV. Data were also obtained for Cu (47 keV to 1.4 MeV) and for Sc, Zn, Nd, Hf, and Pt (1.8 to 20 MeV). The present work is part of a continuing effort to provide accurate neutron total cross sections for evaluations and for optical-model parameteriztions. The latter are required for the derivation of other nuclear-data information of importance to applied programs. 37 references.
Date: May 1, 1983
Creator: Poenitz, W.P. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and scattering cross sections of elemental palladium

Description: Neutron total cross sections of palladium are measured from approx. = 0.6 to 4.5 MeV with resolutions of approx. = 30 to 70 keV at intervals of less than or equal to 50 keV. Differential neutron elastic- and inelastic-scattering cross sections are measured from 1.4 to 3.85 MeV at intervals of 50 to 100 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160/sup 0/. The experimental results are compared with respective quantities given in ENDF/B-V and used to deduce an optical potential that provides a good description of the measured values.
Date: June 1, 1982
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Nonelastic-scattering cross sections of elemental nickel. [1. 3 to 4. 5 MeV]

Description: Neutron total cross sections of elemental nickel were measured from 1.3 to 4.5 MeV, at intervals of approx. 50 keV, with resolutions of 30 to 50 keV and to accuracies of 1 to 2.5%. Neutron differential-elastic-scattering cross sections were measured from 1.45 to 3.8 MeV, at intervals and with resolutions comparable to those of the total cross sections, and to accuracies of 3 to 5%. The nonelastic-scattering cross section is derived from the measured values to accuracies of greater than or equal to 6%. The experimental results are compared with previously reported values as represented by ENDF/B-V, and areas of consistency and discrepancy, noted. The measured results are shown to be in good agreement with the predictions of a model previously reported by the authors. 4 figures, 1 table.
Date: June 1, 1980
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast-neutron interactions with /sup 182/W, /sup 184/W and /sup 186/W

Description: Neutron total cross sections of /sup 182/W, /sup 184/W and /sup 186/W are measured from approx. = 0.3 to 5.0 MeV at intervals of less than or equal to 50 keV to accuracies of 1 to 3%. Differential neutron elastic- and inelastic-scattering cross sections of the same three isotopes are measured at scattering angles in the range 20 to 160/sup 0/ and at incident-neutron energy intervals of approx. = 100 keV from 1.5 to 4.0 MeV. Approximately thirty scattered-neutron groups are observed for each of the isotopes. Prominent of these are excitations attributed to collective rotational and vibrational bands. The experimental results are interpreted in terms of optical-statistical and coupled-channels models with particular attention to the direct excitation of ground-state-rotational and ..beta..- and ..gamma..-vibrational bands. The strengths of the direct interactions and the magnitudes of the collective deformations are inferred from the interpretations and compared with similar values previously reported elsewhere. The experimental results are used to deduce experimentally-based evaluated data sets for /sup 182/W, /sup 184/W and /sup 186/W over the energy range 0.1 - approx. = 5.0 MeV.
Date: June 1, 1981
Creator: Guenther, P.T.; Smith, A.B. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

On-line computer facility and operating system COSACS at the ANL fast neutron generator

Description: An on-line/off-line computer system has been dnstalled at the ANL fast neutron generator (FNG) for on-line data acquisition and storage, and for off- line data reduction and evaluation. An operating system called COSACS has been written specifically for the installation. The present report describes all available hardware and software, but emphasizes those aspects of both that were tailored for this application. The various physicaldata channels, both input and output, are discussed with regard to transfer rates, bit formats, and interrupt control. The general relationship and areas of compatibility of COSACS with standard compilers and assemblers are discussed. A complete tabulation is given of operations available under COSACS, together with their input/output formats. (auth)
Date: August 1, 1973
Creator: Poenitz, W.P. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and scattering cross sections of /sup 103/Rh

Description: Fast-neutron total cross sections of /sup 103/Rh are measured with 30 to 50 keV resolutions from 0.7 to 4.5 MeV. Differential elastic- and inelastic-scattering cross sections are measured from 1.45 to 3.85 MeV. Scattered-neutron groups corresponding to excited levels at 334 +- 13, 536 +- 7, 648 +- 25, 796 +- 20, 864 +- 22, 1120 +- 22, 1279 +- 50, 1481 +- 27, 1683 +- 39, 1840 +- 79, 1991 +- 71 and 2050 (tentative) keV are observed. An optical-statistical model is derived from the elastic-scattering results. The experimental values are compared with comparable quantities given in the ENDF/B-V evaluation.
Date: July 1, 1982
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and scattering cross sections of niobium

Description: Neutron total cross sections of niobium were measured from approx. = 0.7 to 4.5 MeV at intervals of less than or equal to 50 keV with broad resolution. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 4.0 MeV at intervals of 0.1 to 0.2 MeV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Inelastically-scattered neutrons, corresponding to the excitation of levels at: 788 +- 23, 982 +- 17, 1088 +- 27, 1335 +- 35, 1504 +- 30, 1697 +- 19, 1971 +- 22, 2176 +- 28, 2456 +- (.), and 2581 +- (.) keV, were observed. An optical-statistical model, giving a good description of the observables, was deduced from the measured differential-elastic-scattering cross sections. The experimental-results were compared with the respective evaluated quantities given in ENDF/B-V.
Date: July 1, 1982
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Neutron total scattering cross sections of elemental antimony

Description: Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V.
Date: November 1, 1982
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Neutron total and scattering cross sections of some even isotopes of molybdenum and the optical model. [J,. pi. , 1. 6 to 5. 5 MeV]

Description: Neutron total and elastic and inelastic scattering cross sections of /sup 92/Mo, /sup 96/Mo, /sup 98/Mo and /sup 100/Mo were measured. Neutron total cross sections were determined at intervals of less than or equal to 10 keV from 1.6 to 5.5 MeV with resolutions of approximately 10 keV. Neutron elastic and inelastic scattering cross sections were measured from 1.8 to 4.0 MeV at intervals of 0.2 MeV. Neutron groups corresponding to the excitation of forty states were identified. The experimental results were examined in the context of optical- and statistical-nuclear models. It was concluded that the real part of the optical potential includes a term proportional to ((N - Z)/A) and suggested that the imaginary part is shell dependent with decreasing magnitude as N = 50 is approached. Comparison of measured and calculated inelastic neutron excitation cross sections suggested a number of J/sup ..pi../ assignments extending previous knowledge. The experimental and calculational results were used, together with previously reported values, to generate an evaluated neutron total and scattering cross section file in the ENDF format extending over the energy range 0.1 to 8.0 MeV.
Date: June 1, 1974
Creator: Smith, A. B.; Guenther, P. T. & Whalen, J. F.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and scattering cross sections of Cr, Fe and /sup 60/Ni. [1 to 4. 5 MeV]

Description: Neutron total cross sections are measured with broad resolutions (50 to 100 keV) from approx. = 1.0 to 4.5 MeV at intervals of less than or equal to 50 keV and to accuracies of approx. = 1% using a variety of sample thicknesses. Differential elastic-scattering cross sections are measured at greater than or equal to 10 scattering angles distributed between 20 to 160 deg. from approx. = 1.5 to 4.0 MeV at intervals of less than or equal to 50 keV. Angle-integrated elastic scattering cross sections are deduced from the measured values to accuracies greater than or equal to 5%. Inelastic-neutron-scattering cross sections are determined up to incident neutron energies of 4.0 MeV, at scattering angles distributed between 20 to 160 deg., and for 5 observed excitations in Cr, for 7 in Fe and for 6 in /sup 60/Ni. The experimental results are discussed in terms of conventional optical-statistical models with attention to cross section fluctuations and in the context of direct-scattering processes. The experimental and calculational results are compared with the corresponding evaluated quantities given in the ENDF/B file with attention to regions of agreement and inconsistency. 14 references.
Date: January 1, 1979
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Total-neutron cross sections of heavy nuclei. [30 to 4800 keV]

Description: Total-neutron cross sections of the heavy and actinide nuclei /sup 181/Ta, /sup 197/Au, /sup 232/Th, /sup 233/U, /sup 235/U, /sup 238/U, /sup 239/Pu, and /sup 240/Pu were measured from 30 keV to 4.8 MeV. The experimental procedures emphasized a high consistency of the measured data. Systematic uncertainties, excluding those associated with sample masses, were less than or equal to 0.5% and statistical uncertainties were typically less than or equal to 1.0%. At low energies attention was given to resonance self-shielding effects. The experimental results are in good agreement with /sup 232/Th, /sup 233/U, and /sup 238/U data previously reported from this laboratory and at higher energies with the comparable values reported by Foster and Glasgow, excepting /sup 240/Pu which was not studied in the latter work. The measured total-cross-sections were interpreted in terms of a spherical optical model and a deformed coupled-channels model. 31 references.
Date: January 1, 1979
Creator: Poenitz, W.P.; Whalen, J.F. & Smith, A.B.
Partner: UNT Libraries Government Documents Department

Be(d,n) source at a modest facility

Description: Source characterization for deuteron energies less than 8 MeV is discussed including: intensity, spectrum and angular distributions. Pulsed and steady-state applications of the source to the acquisition of fast-neutron data are illustrated by energy-averaged neutron total cross-section and spectrum-averaged activation cross-section measurements. Source utilization, measurement techniques, and experimental results are described with attention to self-shielding effects, background suppression and specification of uncertainties. These illustrations are extrapolated to broader-scope studies, taking advantage of the high fact-neutron intensities. The present and future potential is determined more by detection capability than by source properties. 19 refs., 9 figs.
Date: January 1, 1986
Creator: Smith, A.B.; Smith, D.L. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and elastic-scattering cross sections of elemental indium

Description: Broad-resolution neutron total cross sections of elemental indium were measured from 0.8 to 4.5 MeV. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 3.8 MeV at intervals of approx. = 50 to 200 keV and at scattering angles in the range 20 to 160 degrees. The experimental results are interpreted in terms of the optical-statistical model and are compared with respective values given in ENDF/B-V.
Date: November 1, 1982
Creator: Smith, A.B.; Guenther, P.T. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Cobalt, fast neutrons and physical models: Nuclear data and measurements series

Description: Energy-averaged neutron total cross sections of cobalt were measured from approx. =0.5 to 12.0 MeV. Differential elastic- and inelastic-scattering cross sections were measured from approx. =1.5 to 10.0 MeV over the scattering-angle range approx. =18/sup 0/ to 160/sup 0/, with sufficient detail to define the energy-averaged behavior. Inelastic neutron groups were observed corresponding to ''levels'' at: 1115 +- 29, 1212 +- 24, 1307 +- 24, 1503 +- 33, 1778 +- 40, 2112 +- 40, 2224 +- 35, 2423 +- 39, 2593 +- 41 and 2810 keV. The experimental results were interpreted in terms of the spherical optical-statistical and coupled-channels models. An unusually successful description of observables was achieved over a wide energy range (<-15.0 to > 20.0 MeV) with a spherical model having energy-dependent strengths and geometries. The energy dependencies are large below approx. =7.0 MeV (i.e., approx. =19.0 MeV above the Fermi energy), but become smaller and similar to those reported for ''global'' potentials at higher energies. The imaginary strength is large and decreases with energy. These imaginary-potential characteristics are attributed to neutron shell closure and collective-vibrational processes. The weak-coupling model also offers an explanation of the unusual negative energy slope and relatively small radius of the imaginary potential. The spherical optical model derived from the neutron-scattering results was extrapolated to bound energies using the dispersion relationship and the method of moments. The resulting real-potential strength and radius peak at approx. =-10.0 MeV, while concurrently the real diffuseness is at a minimum. The extrapolated potential is approx. =8% larger than that implied by reported particle-state energies, and approx. =13% smaller than indicated by hole-state energies. 68 refs., 15 figs., 1 tab.
Date: July 1, 1987
Creator: Smith, A.B.; Guenther, P.T.; Whalen, J.F. & Lawson, R.D.
Partner: UNT Libraries Government Documents Department

Fast-neutron total and scattering cross sections of /sup 58/Ni

Description: Neutron total cross sections of /sup 58/Ni were measured at 25 keV intervals from 0.9 to 4.5 MeV with 50 to 100 keV resolutions. Attention was given to self-shielding corrections to the observed total cross sections. Differential elastic- and inelastic-scattering cross sections were measured at 50 keV intervals from 1.35 to 4.0 MeV with 50 to 100 keV resolutions. Inelastic excitation of levels at 1.458 +- 0.009, 2.462 +- 0.010, 2.791 +- 0.015, 2.927 +- 0.012 and 3.059 +- 0.025 MeV was observed. The experimental results were interpreted in terms of optical-statistical and coupled-channels models. A spherical optical-statistical model was found generally descriptive of an energy-average of the experimental results. However, detailed considerations suggested significant contributions from direct-vibrational interactions, particularly associated with the excitation of the first 2+ level.
Date: September 1, 1981
Creator: Jorgensen, C.B.; Guenther, P.T.; Smith, A.B. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Fast neutron total and scattering cross sections of chromium, iron and /sup 60/Ni. [50 to 100 keV]

Description: Neutron total cross sections are measured with broad resolutions (50 to 100 keV) from approx. = 1.0 to 4.5 MeV at intervals of less than or equal to 50 keV and to accuracies of approx. = 1%. Differential elastic scattering cross sections are measured at greater than or equal to 10 scattering angles distributed between 20 and 160/sup 0/ from approx. = 1.5 to 4.0 MeV at intervals of less than or equal to 50 keV. Angle-integrated elastic scattering cross sections are deduced from the measured values to accuracies of greater than or equal to 5%. Inelastically scattered neutrons are observed up to incident neutron energies of 4.0 MeV at scattering angles distributed between 20 and 160/sup 0/. Cross sections are determined corresponding to the excitation of observed states at: Chromium - 1433, 2377, 2665, 2778, and 2970 keV; Iron - 853, 1389, 2097, 2579, 2677, 2974, and 3152 keV; and /sup 60/Ni - 1342, 2168, 2304, 2509, 2636, and 3164 keV. The experimental results are discussed in terms of conventional optical-statistical models and in the context of direct-scattering processes. The experimental and calculational results are compared with the corresponding evaluated quantities given in the ENDF/B file. 21 references.
Date: January 1, 1979
Creator: Smith, A B; Guenther, P T & Whalen, J F
Partner: UNT Libraries Government Documents Department

Some comments on the interaction of fast-neutrons with beryllium

Description: Neutron total cross sections of elemental beryllium were measured from 1 to > 10 MeV with good precision. Differential neutron elastic-scattering cross sections were measured from 4.5 to 10 MeV at energy intervals of approx.0.5 MeV, and for approx. 100 angular steps distributed between 18/degree/ and 160/degree/ at each incident energy. Concurrently, differential cross sections for the emission of a discrete inelastic-neutron group corresponding to an excited level at 2.43 +- 0.06 MeV were determined over the same incident-energy and angular range. Angle-integrated elastic-scattering cross sections were deduced from the observed differential values to accuracies of 2.5%, and angle-integrated inelastic-scattering cross sections were established to accuracies of less than or equal to 10%. The experimental results are compared with values given in ENDF/B-V, with attention to discrepancies and implications. Qualitative reaction mechanisms are suggested. 27 refs., 8 figs., 1 tab.
Date: November 1, 1988
Creator: Sugimoto, M.; Guenther, P.T.; Lynn, J.E.; Smith, A.B. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department