Modeling Fission-Fragment Properties

We are one year into an LDRD-DR entitled "Advancing the Fundamental Understanding of Fission." The goals of this work are to advance our ability to measure the fission fragments as a function of the neutron incident energy causing fission, to improve the theoretical modeling of the same and to test the modeling against the new data. The status of the experimental work will be presented elsewhere (next up 9AM Monday 12/17 at the Rosen auditorium at LANSCE). Today's talk will outline the work to date and plans associated with the theoretical modeling.

Starting from the very successful global nuclear structure model developed by Moller and Nix, we are developing a dynamical model of fission. We will outline why we think a predictive dynamical model is feasible, the method of calculation, and the observables which will be calculated. These include distributions of and correlations among: fission-fragment Z, A, final kinetic energies, and excitation energies when neutron emission begins.

In addition to the more complete model described above, heuristic methods have been developed to extrapolate measured first-chance fission-product yields and average fragment total kinetic energies to higher incident-neutron energies where second, third, and forth chance fission are of importance. Predictions are made for the energy dependence of plutonium fission-product yields and the average total kinetic energy of 239Pu(n,f) fission fragments, up to a neutron energy of 20 MeV.