Pre-saddle neutron multiplicity for fission reactions induced by heavy ions and light particles

Abstract

Pre-saddle neutron multiplicity has been calculated for several fission reactions induced by heavy ions and light particles. Experimentally, it is impossible to determine the contribution of neutrons being emitted before the saddle point and those emitted between the saddle and the scission points.Determination of the pre-saddle neutron multiplicity in our research is based on the comparison between the experimental anisotropies and those predicted by the standard saddle-point statistical model. Analysis of the results shows that the pre-saddle neutron multiplicity depends on the fission barrier height and stability of the compound nucleus. In heavy ion induced fission, the number of pre-saddle neutrons decreases with increasing the excitation energy of the compound nucleus.A main cause of this behavior is due to a reduction in the ground state-to-saddle point transition time with increasing the excitation energy of the compound nucleus. Whereas in induced fission by light particles, the number of pre-saddle neutrons increases with increasing the excitation energy of the compound nucleus.

Fission fragment mass distribution studies inSi30+Hf180reaction

“…a is the level density parameter, calculated as a = A CN /10, where A CN is the mass of the CN. E sad pre is given by [46] E sad pre = N sad pre × (B n + E n ) (4) where N sad pre is the pre-saddle neutron multiplicity, B n is the neutron binding energy and E n = 2 × T cn is the average kinetic energy of emitted neutrons where T cn is the temperature of the CN.…”