Point-by-point model calculation of the prompt neutron multiplicity distribution ν(A) in the incident neutron energy range of multi-chance fission

Prompt neutron multiplicity distributions ν(A) are required for prompt emission correction of double energy (2E) measurements of fission fragments to determine pre-neutron fragment properties. The lack of experimental ν(A) data especially at incident neutron energies (En) where multiple fission chances are involved impose the use of ν(A) predicted by models. The PbP model of prompt emission is able to provide the individual ν(A) of the compound nuclei of the main and secondary nucleus chains undergoing fission at a given En. The total ν(A) is obtained by averaging these individual ν(A) over the fission chance probabilities (expressed as total and partial fission cross-section ratios). An indirect validation of the total ν(A) results is proposed. At high En, above 70 MeV, the PbP results of individual ν(A) of the first few nuclei of the main and secondary nucleus chains exhibit an almost linear increase. This shape is explained by the damping of shell effects entering the super-fluid expression of the level density parameters. They tend to approach the asymptotic values for a great part of the fragments. This fact leads to a smooth and almost linear increase of fragment excitation energy with the mass number that is reflected in a smooth and almost linear behaviour of ν(A).

TUDORA A.;  HAMBSCH Franz-Josef;  TOBOSARU V.; 

2017-10-25

EDP Sciences

JRC103418

2100 014X,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC103418,   

10.1051/epjconf/201714604004,