PRIMARY CHARGE OF FISSION PRODUCTS FROM THERMAL NEUTRON FISSION OF 235U

The average primary charge Zp of fission products from thermal neutron fission of 235U is determined by measuring the number of β-decays suffered by the fission products, which are mass separated with the gas-filled mass separator of the research reactor FRJ-2. The measurement is performed with a 4π plastic detector to avoid errors caused by conversion electrons and γ-rays emitted in coincidence with β-decays It is extended over the mass ranges 86 < A < 104 and 137 < A < 143 for light and heavy fission products, respectively. The results are represented by a linear relationship between Zp and the mass Ap of the fission products before prompt neutron emission The mean deviation of Zp from the unchanged charge density charge amounts to +0 41 and -0 41 charge units for light and heavy fission products, respectively. The standard deviation for the primary charge distribution for all fission products with equal mass averaged over all fission product masses is estimated to be σ = 0 59 ± 0.03 charge units. © 1969.