Role of Effective Distance in the Fission Mechanism Study by the Doubleenergy Measurement for Uranium Iaotopes
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Abstract
<BR>Fission product kinetic energies were measured by the doubleenergy method for thermalneutron fission of 235, 233U and protoninduced fission of 238U at the 15.8MeV excitation. From the obtained energymass correlation data, the kineticenergy distribution was constructed from each mass bin to evaluate the first moment of the kinetic energy for a given fragment mass. The resulting kinetic energy was then converted to the effective distance between the charge centers at the moment of scission. The effective distances deduced for the protoninduced fission was concluded to be classified into two constant values, one for asymmetric and the other for symmetric mode, irrespective of the mass though an additional component was further extracted in the asymmetric mass region. This indicates that the fission takes place via two welldefined saddles, followed by the random neck rupture. On the contrary, the effective distances obtained for thermalneutron induced fission turned out to lie along the contour line at the same level as the equilibrium deformation in the twodimensional potential map. This strongly suggests that it is essentially a barrierpenetrating type of fission rather than the overbarrier fission.
Journal

 Journal of Nuclear Science and Technology

Journal of Nuclear Science and Technology 34(9), 871881, 19970925
Atomic Energy Society of Japan