Isospin dependence of scission-neutron multiplicities in Pu isotopes

In contrast to prompt neutrons, scission neutrons are expected to mostly depend on the characteristics of the fissioning nucleus and, in particular, on its neutron number N. We have studied this effect for a series of plutonium isotopes in the framework of the sudden approximation. We have found a continuous nonnegligible increase of scission-neutron multiplicities from 236Pu (νsc = 0.318 n/fission) to 256Pu (νsc = 0.597 n/fission) reflecting the increase in the amount of available neutrons in the system. This increase is irregular owing to the dependence of the partial emission probability on the quantum numbers of the single-neutron states involved