Abstract
Full text: Recent experiments in GANIL (France) revealed that the average fission times <t{sub f}f> of uranium-like nuclei excited up to 250 MeV are much longer than the time scales usually inferred from either neutron or {gamma}-ray pre-scission multiplicities (<n{sub pre}> and <y{sub pre}> respectively). In order to solve this puzzle, calculations have been done by means of the computer code CDSM2. The code simulates the fission process dynamically in the space of two collective degrees of freedom corresponding to the elongation- and mass-asymmetry modes. Light particle emission from the excited nuclei is considered statistically. Calculations performed with reduced value of the one-body dissipation are in agreement with measured <t{sub f}> of uranium isotopes, as well as with <n{sub pre}> and <g{sub pre}> from the {sup 16}O+{sup 208}Pb fusion-fission reaction. This is encouraging us to make some predictions about the excitation energy dependence of <t{sub f}> and <n{sub pre}> for the isotopes of lead excited up to 250 MeV. In contrast to the uranium case, for these nuclei the calculated <t{sub f}> of the fission events accompanied by light charged particle emission are found to be shorter than the times of the events where only neutrons are emitted prior to
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Gontchar, I I;
[1]
Morjean, M;
Basnary, S;
[2]
Litnevsky, L A;
Ponomarenko, N A
[3]
- The Australian National University, Canberra, ACT (Australia). Research School of Physical Sciences and Engineering, Department of Nuclear Physics
- GANIL Grand Accelerateur National d'Ions Lourds, (France)
- Omsk State Railway University, Omsk (Russian Federation). Physics and Chemistry Department
Citation Formats
Gontchar, I I, Morjean, M, Basnary, S, Litnevsky, L A, and Ponomarenko, N A.
Theoretical fission times for U and Pb nuclei excited up to 250 MeV.
Australia: N. p.,
2002.
Web.
Gontchar, I I, Morjean, M, Basnary, S, Litnevsky, L A, & Ponomarenko, N A.
Theoretical fission times for U and Pb nuclei excited up to 250 MeV.
Australia.
Gontchar, I I, Morjean, M, Basnary, S, Litnevsky, L A, and Ponomarenko, N A.
2002.
"Theoretical fission times for U and Pb nuclei excited up to 250 MeV."
Australia.
@misc{etde_20619906,
title = {Theoretical fission times for U and Pb nuclei excited up to 250 MeV}
author = {Gontchar, I I, Morjean, M, Basnary, S, Litnevsky, L A, and Ponomarenko, N A}
abstractNote = {Full text: Recent experiments in GANIL (France) revealed that the average fission times <t{sub f}f> of uranium-like nuclei excited up to 250 MeV are much longer than the time scales usually inferred from either neutron or {gamma}-ray pre-scission multiplicities (<n{sub pre}> and <y{sub pre}> respectively). In order to solve this puzzle, calculations have been done by means of the computer code CDSM2. The code simulates the fission process dynamically in the space of two collective degrees of freedom corresponding to the elongation- and mass-asymmetry modes. Light particle emission from the excited nuclei is considered statistically. Calculations performed with reduced value of the one-body dissipation are in agreement with measured <t{sub f}> of uranium isotopes, as well as with <n{sub pre}> and <g{sub pre}> from the {sup 16}O+{sup 208}Pb fusion-fission reaction. This is encouraging us to make some predictions about the excitation energy dependence of <t{sub f}> and <n{sub pre}> for the isotopes of lead excited up to 250 MeV. In contrast to the uranium case, for these nuclei the calculated <t{sub f}> of the fission events accompanied by light charged particle emission are found to be shorter than the times of the events where only neutrons are emitted prior to scission.}
place = {Australia}
year = {2002}
month = {Jul}
}
title = {Theoretical fission times for U and Pb nuclei excited up to 250 MeV}
author = {Gontchar, I I, Morjean, M, Basnary, S, Litnevsky, L A, and Ponomarenko, N A}
abstractNote = {Full text: Recent experiments in GANIL (France) revealed that the average fission times <t{sub f}f> of uranium-like nuclei excited up to 250 MeV are much longer than the time scales usually inferred from either neutron or {gamma}-ray pre-scission multiplicities (<n{sub pre}> and <y{sub pre}> respectively). In order to solve this puzzle, calculations have been done by means of the computer code CDSM2. The code simulates the fission process dynamically in the space of two collective degrees of freedom corresponding to the elongation- and mass-asymmetry modes. Light particle emission from the excited nuclei is considered statistically. Calculations performed with reduced value of the one-body dissipation are in agreement with measured <t{sub f}> of uranium isotopes, as well as with <n{sub pre}> and <g{sub pre}> from the {sup 16}O+{sup 208}Pb fusion-fission reaction. This is encouraging us to make some predictions about the excitation energy dependence of <t{sub f}> and <n{sub pre}> for the isotopes of lead excited up to 250 MeV. In contrast to the uranium case, for these nuclei the calculated <t{sub f}> of the fission events accompanied by light charged particle emission are found to be shorter than the times of the events where only neutrons are emitted prior to scission.}
place = {Australia}
year = {2002}
month = {Jul}
}