Theoretical investigation on shell and deformation effects on most probable charge in nuclear fission

The most probable charge Z sub(P) is obtained from Myers and Swiatecki mass formula by analytical method and the Z sub(P) is expressed in terms of the part of simple liquid drop model, the shell and deformation effects. The deviation of the predicted Z sub(P)-value from the Z sub(P)sup(UCD) based on the unchanged charge distribution can be well interpreted by these terms. The shell effect shows the saw-tooth curve and the deformation effect shows a hump on the range of mass numbers where the shell function S(N, Z) exceeds the critical value Scrit introduced by Myers and Swiatecki. The predicted Z sub(P)-values fairly well agree with the semi-empirical result obtained by Wahl and the fine structure is well reproduced. The magnitudes of the shell and deformation effects in the thermal neutron fission of 235U are about 0.7 and 0.25 charge units, respectively and both effects act so as to cancell each other. (auth.)