Fast fission mechanism and duality of the diffusion process
H. Baba - N. Takahashi - A. Yokoyama - T. Saito
Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560, Japan
Received: 11 November 1997 Communicated by P. Armbruster
Abstract
The reaction of 238U with 12C was studied radiochemically with the
purpose of elucidating fast fission characteristics. From the difference in the mass
distribution below and above the critical energy where fast fission is predicted to set in,
fast fission component was extracted in far-asymmetric mass region and interpreted as the
mass diffusion following the Fokker-Planck equation. Anomalous charge dispersion widths in
the corresponding mass region and a sudden increase of the whole mass distribution width at
the critical energy were also observed to support the above result. The reaction time of
fast fission deduced from the width and position of the mass distribution was
510-21s as well by taking into account the effect of neutron emission during
the diffusion process, which turned out to be more than one order of magnitude longer than
the corresponding life time of typical deep inelastic scattering but substantially short
compared to ordinary fusion-fission life time. Evaluation of the driving potential for mass
drift required dinuclear configuration be of an elongated or deformed form for fast fission
in contrast to a more compact form for the deep-inelastic process.
PACS
25.70.Jj Fusion and fusion-fission reactions -
25.85.Ge Charged-particle-induced fission
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