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Entrance channel effects in fission of {sup 197}Tl

Journal Article · · Physical Review. C, Nuclear Physics
The pre- and post-scission neutron multiplicities are measured for {sup 16}O+{sup 181}Ta and {sup 19}F+{sup 178}Hf systems where the same compound nucleus {sup 197}Tl is formed at the same excitation energies (E*=72, 76, and 81 MeV). The measured pre-scission neutron multiplicities are found to be different for the two reactions and this difference in neutron yield increases with the excitation energy of the compound nucleus. The experimental pre-scission neutron yield is compared with predictions from the statistical model of compound nuclear decay containing the strength of nuclear viscosity as a free parameter. The magnitude of nuclear viscosity required to fit the experimental yield is found to be different for the two reactions. Because the two systems under consideration lie on the two sides of the Businaro-Gallone point, this observation indicates that the entrance channel mass asymmetry plays an important role in determining the number of neutrons emitted prior to scission in fusion-fission reactions.
OSTI ID:
21067822
Journal Information:
Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 76; ISSN 0556-2813; ISSN PRVCAN
Country of Publication:
United States
Language:
English