Nuclear charge dispersion of light-mass fission products in the fission of 235U and 238U by medium-energy protons

Abstract

Independent fission yields for ⁹⁰Y^m, ⁹⁰Y^m+g, ⁹¹Y^m, ⁹¹Y^m+g, and ⁹²Y and cumulative yields for ⁹¹Sr, ⁹²Sr, and ⁹³Y in the fission of ²³⁵U and ²³⁸U by protons of energy from 20–85 MeV have been determined. Excitation functions and charge dispersion curves have been obtained. The most probable charge, Z_p, moves closer to stability, Z_A, with increasing energy. The values of Z_A − Z_p for the two fissioning systems are identical, unlike the situation in the heavy-mass region. The values of Z_A − Z_p for the light- and heavy-mass regions differ considerably, showing that the equal charge displacement hypothesis does not hold even at these moderate energies.