Abstract
Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of {sup 16,18}O, {sup 40}Ar and {sup 64}Ni. A new method of interpretation of experimental pre-scission neutron multiplicities {nu}-pre and mean kinetic energies {epsilon}{sub {nu}} allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35{+-}15) x 10{sup -21}s for symmetric fission. All reactions show that {nu}-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of {nu}-pre on TKE, whilst for {sup 64}Ni-induced quasi-fission reactions, a strong increase of {nu}-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in
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Hinde, D J;
[1]
Hilscher, D;
Rossner, H;
Gegauer, B N;
Lehmann, M;
Wilpert, M
[2]
- Australian National Univ., Canberra (Australia). Research School of Physical Sciences
- Hahn-Meitner-Institut Berlin GmbH (Germany)
Citation Formats
Hinde, D J, Hilscher, D, Rossner, H, Gegauer, B N, Lehmann, M, and Wilpert, M.
Neutron emission as a probe of fusion-fission and quasi-fission dynamics.
Australia: N. p.,
1991.
Web.
Hinde, D J, Hilscher, D, Rossner, H, Gegauer, B N, Lehmann, M, & Wilpert, M.
Neutron emission as a probe of fusion-fission and quasi-fission dynamics.
Australia.
Hinde, D J, Hilscher, D, Rossner, H, Gegauer, B N, Lehmann, M, and Wilpert, M.
1991.
"Neutron emission as a probe of fusion-fission and quasi-fission dynamics."
Australia.
@misc{etde_10136038,
title = {Neutron emission as a probe of fusion-fission and quasi-fission dynamics}
author = {Hinde, D J, Hilscher, D, Rossner, H, Gegauer, B N, Lehmann, M, and Wilpert, M}
abstractNote = {Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of {sup 16,18}O, {sup 40}Ar and {sup 64}Ni. A new method of interpretation of experimental pre-scission neutron multiplicities {nu}-pre and mean kinetic energies {epsilon}{sub {nu}} allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35{+-}15) x 10{sup -21}s for symmetric fission. All reactions show that {nu}-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of {nu}-pre on TKE, whilst for {sup 64}Ni-induced quasi-fission reactions, a strong increase of {nu}-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs.}
place = {Australia}
year = {1991}
month = {Aug}
}
title = {Neutron emission as a probe of fusion-fission and quasi-fission dynamics}
author = {Hinde, D J, Hilscher, D, Rossner, H, Gegauer, B N, Lehmann, M, and Wilpert, M}
abstractNote = {Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of {sup 16,18}O, {sup 40}Ar and {sup 64}Ni. A new method of interpretation of experimental pre-scission neutron multiplicities {nu}-pre and mean kinetic energies {epsilon}{sub {nu}} allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35{+-}15) x 10{sup -21}s for symmetric fission. All reactions show that {nu}-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of {nu}-pre on TKE, whilst for {sup 64}Ni-induced quasi-fission reactions, a strong increase of {nu}-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs.}
place = {Australia}
year = {1991}
month = {Aug}
}