Isospin conservation in compound nuclear fusion–fission reactions – empirical evidence

Isospin symmetry has gained importance in nuclear phenomena involving heavy nuclei in recent years. We present empirical evidence of isospin dependence in the compound nuclear fission cross-sections and fission widths, which suggests the idea that the compound nucleus (CN) possibly retains the memory of the isospin when it is formed and affects the CN fission. This idea was first proposed by E.L. Yadrovsky [E.L. Yadrovsky, Phys. Lett. 55B, 157 (1975)]. An observable difference between the fission branching ratios in two different isospin states suggests that the CN seems to remember its isospin at the point of formation. Further, the data also suggest a possible new signature of weakening of the CN process and gradual transition to non-compound processes as the energy rises. This is a very interesting and useful observation which needs to be confirmed by further and more precise experiments.