No influence of a N=126 Neutron Shell Closure in Fission Fragment Mass Distributions

TL;DR

This study measures fission fragment mass distributions in $^{206}$Po and $^{210}$Po, finding no evidence of shell effects at N=126, challenging previous assumptions and providing data for testing fission models.

Contribution

It provides the first direct experimental comparison of mass distributions in nuclei with and without the N=126 shell closure, showing no shell correction at the saddle point.

Findings

No significant difference in mass distributions between $^{206}$Po and $^{210}$Po.

Contradicts previous reports of shell effects at N=126.

Offers benchmark data for fission dynamical models.

Abstract

Mass distributions of the fragments in the fission of $^{206}$Po and the N=126 neutron shell closed nucleus $^{210}$Po have been measured. No significant deviation of mass distributions has been found between $^{206}$Po and $^{210}$Po, indicating the absence of shell correction at the saddle point in both the nuclei, contrary to the reported angular anisotropy and pre-scission neutron multiplicity results. This new result provides benchmark data to test the new fission dynamical models to study the effect of shell correction on the potential energy surface at saddle point.