Determination of nuclear friction in strongly damped reactions from prescission neutron multiplicities

Journal Article · Mon Jul 01 04:00:00 EDT 1996 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.54.325· OSTI ID:286206

Wilczynski, J ^[1]; Siwek-Wilczynska, K ^[2]; Wilschut, H W ^[3]

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1. Soltan Institute for Nuclear Studies, 05-400 Swierk-Otwock (Poland)
2. Institute of Experimental Physics, Warsaw University, 00-681 Warsaw (Poland)
3. Kernfysisch Versneller Instituut, 9747 AA Groningen (The Netherlands)

Nonfusion, fissionlike reactions in collisions of four heavy systems (well below the fusion extra-push energy threshold), for which Hinde and co-workers had measured the prescission neutron multiplicities, have been analyzed in terms of the deterministic dynamic model of Feldmeier coupled to a time-dependent statistical cascade calculation. In order to reproduce the measured prescission multiplicities and the observed (nearly symmetric) mass divisions, the energy dissipation must be dramatically changed with regard to the standard one-body dissipation: In the entrance channel, in the process of forming a composite system, the energy dissipation has to be reduced to at least half of the one-body dissipation strength ({ital k}{sub {ital s}}{sup in}{le}0.5), and in the exit channel (from a mononucleus shape to scission) it must be increased by a factor ranging for the studied reactions from {ital k}{sub {ital s}}{sup out}=4 to {ital k}{sub {ital s}}{sup out}=12. These results are compared with the temperature dependence of the friction coefficient, recently deduced by Hofman, Back, and Paul from data on the prescission giant dipole resonance emission in fusion-fission reactions. The combined picture of the temperature dependence of the friction coefficient, for both fusion-fission and nonfusion reactions, may indicate the onset of strong two-body dissipation already at a nuclear temperature of about 2 MeV. {copyright} {ital 1996 The American Physical Society.}

• OSTI ID: 286206
• Journal Information: Physical Review, C, Journal Name: Physical Review, C Journal Issue: 1 Vol. 54; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DIPOLES
FISSION
FRICTION
GIANT RESONANCE
MASS
MULTIPLICITY
NEUTRONS
NUCLEAR TEMPERATURE
TEMPERATURE DEPENDENCE
TIME DEPENDENCE