Correlated fission fragment spin dynamics

The Langevin treatment of the dissipative nuclear shape evolution is used to generate large samples of events for a number of fission cases. Within the nucleon-exchange model, the resulting time-dependent shape parameters, as well as the nuclear temperature, determine the drift and diffusion coefficients for the correlated evolution of the angular momenta carried by the two fledging binary parts of the fissioning system. The associated Fokker-Planck transport equation is then solved for the evolving spin-spin covariance tensor for the fission cases considered. The character of the final correlated spin-spin distribution depends on the magnitudes of the relaxation times for the various dinuclear rotational modes, relative to the saddle-to-scission time in each event, resulting in scenarios ranging from only partially to fully equilibrated.