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

TL;DR

This paper calculates pre-saddle neutron multiplicity in fission reactions induced by heavy ions and light particles, revealing its dependence on excitation energy and nuclear stability through comparison with experimental anisotropies.

Contribution

It introduces a method to estimate pre-saddle neutron multiplicity using anisotropy data and the saddle-point statistical model, highlighting its dependence on excitation energy and nuclear properties.

Findings

Pre-saddle neutron multiplicity decreases with excitation energy in heavy ion fission.

Pre-saddle neutron multiplicity increases with excitation energy in light particle fission.

The multiplicity depends on fission barrier height and compound nucleus stability.

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.