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The structures in the total kinetic energy (TKE) distributions in cold fission of 234U and 236U are interpreted in terms of the Coulomb interaction energy (C) between fragments at the scission point. The maximal value of C, Ca,x, corresponding to the most compact scission configuration, is calculated for several mass fragmentations. It is shown that with Q being constant, Cmax increases if one increases the charge asymmetry for a given primary fragmentation. This condition produces oscillations with a period of approximately 5 amu of Cmax as a function of the light fragment mass which are correlated with the observed oscillations of the maximal value of TKE. Moreover, the enhancement of the yields of the more asymmetric charge fragmentation for a given fragmentation is explained.

The time-of-flight technique was used to measure the mass and kinetic energy distribution of fragments from fission of 233U, 235U and 239pu, induced by thermal neutrons at the Grenoble High Flux Reactor. The data array is presented as equal probability lines in the high kinetic energy regions. The fluctuations observed in those experimental lines are explained by a static scission configuration model, in which the most important influence comes from the Coulomb interaction energy between the two fragments. The highest values of total kinetic energy are obtained for fragmentations with heavy fragments Z = 50-52, N = 80-82 and light fragments Z = 40-42, N = 60-64.

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