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Title: Effect of preequilibrium spin distribution on {sup 48}Ti +n cross sections

Abstract

Nuclear model calculations of discrete {gamma}-ray production cross sections produced in {sup 48}Ti(n,n{sup '}{gamma}{sub i}){sup 48}Ti and {sup 48}Ti(n,2n{gamma}{sub i}){sup 47}Ti reactions were made as a function of incident neutron energy from E{sub n}=1 MeV to 35 MeV and compared with new experimental results using the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE) at LANSCE. The Hauser-Feshbach reaction code GNASH, incorporating the spin distribution for the preequilibrium process calculated with the Feshbach-Kerman-Koonin (FKK) quantum-mechanical preequilibrium theory, was used to calculate partial {gamma}-ray transition cross sections. The comparisons of calculated and experimental data demonstrate that, the FKK model for preequilibrium leads a better overall reproduction of the experimental data above E{sub n}=10 MeV, where preequilibrium processes are important. The FKK calculation predicts a strong reduction in the high-spin state population in {sup 48}Ti by inelastic scattering. Population of low-spin states was also affected, however the change in the low-lying 983.5-keV (2{sup +}) state production is small because almost all {gamma}-ray decay cascades feed this transition. In addition, the FKK calculation has a significant impact on the partial {gamma}-ray transition cross sections for the (n,2n) reaction above E{sub n}=15 MeV. The calculated cross sections for high-spin states in {sup 47}Timore » are reduced, and those from the low-spin states are enhanced, in agreement with the experimental cross section data.« less

Authors:
 [1];  [2];  [2]; ; ; ; ;  [3];  [4];  [5]; ; ; ;  [4];  [1];  [2]
  1. North Carolina State University, Raleigh, North Carolina 27695 (United States)
  2. (United States)
  3. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  4. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
  5. (Canada)
Publication Date:
OSTI Identifier:
20995298
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.054612; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COMPARATIVE EVALUATIONS; CROSS SECTIONS; DISTRIBUTION; EXCITATION; GAMMA RADIATION; GERMANIUM; HIGH SPIN STATES; INELASTIC SCATTERING; KEV RANGE 100-1000; MEV RANGE; NEUTRONS; NUCLEAR MODELS; QUANTUM MECHANICS; SPIN; TITANIUM 47; TITANIUM 48

Citation Formats

Dashdorj, D., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, Lawrence Livermore National Laboratory, Livermore, California 94551, Kawano, T., Chadwick, M. B., Devlin, M., Fotiades, N., Nelson, R. O., Garrett, P. E., Department of Physics, University of Guelph, Guelph, Ontario N1G2W1, Becker, J. A., Agvaanluvsan, U., Bernstein, L. A., Younes, W., Mitchell, G. E., and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708. Effect of preequilibrium spin distribution on {sup 48}Ti +n cross sections. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054612.
Dashdorj, D., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, Lawrence Livermore National Laboratory, Livermore, California 94551, Kawano, T., Chadwick, M. B., Devlin, M., Fotiades, N., Nelson, R. O., Garrett, P. E., Department of Physics, University of Guelph, Guelph, Ontario N1G2W1, Becker, J. A., Agvaanluvsan, U., Bernstein, L. A., Younes, W., Mitchell, G. E., & Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708. Effect of preequilibrium spin distribution on {sup 48}Ti +n cross sections. United States. doi:10.1103/PHYSREVC.75.054612.
Dashdorj, D., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, Lawrence Livermore National Laboratory, Livermore, California 94551, Kawano, T., Chadwick, M. B., Devlin, M., Fotiades, N., Nelson, R. O., Garrett, P. E., Department of Physics, University of Guelph, Guelph, Ontario N1G2W1, Becker, J. A., Agvaanluvsan, U., Bernstein, L. A., Younes, W., Mitchell, G. E., and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708. Tue . "Effect of preequilibrium spin distribution on {sup 48}Ti +n cross sections". United States. doi:10.1103/PHYSREVC.75.054612.
@article{osti_20995298,
title = {Effect of preequilibrium spin distribution on {sup 48}Ti +n cross sections},
author = {Dashdorj, D. and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708 and Lawrence Livermore National Laboratory, Livermore, California 94551 and Kawano, T. and Chadwick, M. B. and Devlin, M. and Fotiades, N. and Nelson, R. O. and Garrett, P. E. and Department of Physics, University of Guelph, Guelph, Ontario N1G2W1 and Becker, J. A. and Agvaanluvsan, U. and Bernstein, L. A. and Younes, W. and Mitchell, G. E. and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708},
abstractNote = {Nuclear model calculations of discrete {gamma}-ray production cross sections produced in {sup 48}Ti(n,n{sup '}{gamma}{sub i}){sup 48}Ti and {sup 48}Ti(n,2n{gamma}{sub i}){sup 47}Ti reactions were made as a function of incident neutron energy from E{sub n}=1 MeV to 35 MeV and compared with new experimental results using the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE) at LANSCE. The Hauser-Feshbach reaction code GNASH, incorporating the spin distribution for the preequilibrium process calculated with the Feshbach-Kerman-Koonin (FKK) quantum-mechanical preequilibrium theory, was used to calculate partial {gamma}-ray transition cross sections. The comparisons of calculated and experimental data demonstrate that, the FKK model for preequilibrium leads a better overall reproduction of the experimental data above E{sub n}=10 MeV, where preequilibrium processes are important. The FKK calculation predicts a strong reduction in the high-spin state population in {sup 48}Ti by inelastic scattering. Population of low-spin states was also affected, however the change in the low-lying 983.5-keV (2{sup +}) state production is small because almost all {gamma}-ray decay cascades feed this transition. In addition, the FKK calculation has a significant impact on the partial {gamma}-ray transition cross sections for the (n,2n) reaction above E{sub n}=15 MeV. The calculated cross sections for high-spin states in {sup 47}Ti are reduced, and those from the low-spin states are enhanced, in agreement with the experimental cross section data.},
doi = {10.1103/PHYSREVC.75.054612},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}