Systematic on fission fragment mass distribution of ²³⁵U fission

Abstract
Based on the fission fragment mass distribution data up to 20 MeV measured by Hambsch with double kinetic energy method (KEM) and other chain yield data measured with radio active method (RAM), the systematic of fission fragment mass distribution was investigated by using 5 Gaussian model. A code of nonlinear least squares method was developed and the parameters, called discrete parameters, were deduced by fitting the experimental data at each energy point measured. The discrete parameters as functions of energy were fitted with second order functions by least squares method, so that the parameters, called systematic parameters, can be calculated at any energy point. With the systematic, the yields of any mass A at any energy in the region from 0 to 20 MeV can be calculated. The calculated results could reproduce the experimental data measured with KEM well, but show somewhat systematical difference from the data measured by RAM, which reflects there is some systematical difference between the two kinds of measured data. The possible reason is that the data measured by KEM need more complicated accurate corrections.