Experimental estimation of the “scission” neutron yield in the thermal neutron induced fission of 233U and 235U

The analysis of angular and energy distributions of prompt neutrons from the thermal neutron induced fission of 233 U and 235 U measured recently in the WWR-M research reactor (Gatchina, Russia) have been performed. The yield of “scission” neutrons has been estimated by comparing the measured distributions with calculations within the model of emission of neutrons from completely accelerated fragments. Besides taking into account “scission” neutrons, for the best description of measured angular and energy distributions of fission neutrons, the calculation should be performed under the assumption that neutrons with a higher (7-9%) probability are emitted along the fission axis in the center-of-mass system of fission fragments.