Fragment angular distribution as a probe of fission dynamics in nuclei with two classes of excited states

Abstract

The fragment angular distribution from the multichance fission of excited nuclei with a double humped fission barrier is considered. It is shown that the fragment angular distribution is determined by contributions related to both the saddle points. The relative weights of these contributions are calculated in the framework of the diffusion model. The possibility of determining the nuclear dissipation is discussed. A comparison of the experimental data with the calculations leads to a value of the reduced dissipation coefficient β = (0.2 − 0.5) × 10 21 s −1 for the Pu isotopes produced in the 238 U + α reaction at E α = 37 and 43 MeV.

Role of asymmetry parameter and dissipation coefficient ofKcoordinate in angular distribution of fission fragments

“…Therefore, theoretical analysis of different experimental data related to nuclear dissipation becomes of extreme importance. An observable of fission reaction such as the angular distribution of fission fragments also depends on the durations of the different stages of the evolution of a fissioning system and its analysis makes it possible to obtain information about the mechanism of nuclear dissipation [7].…”