Influence of angular momentum on fission fragment mass distribution: Interpretation within Langevin dynamics

Dependence of fission fragments mass distribution on the angular momentum within Langevin dynamics is studied. The calculations are performed in the framework of the rotating temperature-dependent finite-range liquid drop model. The calculations are done for the five nuclei, representing heavy fissioning nuclei, medium fissioning nuclei and light fissioning one with the angular momentum varied in the wide range from l = 0 to l = 70h. The dependence coefficients d sigma(2)(M)/dl(2) for the investigated nuclei are extracted. The comparison of the extracted values with the experimental data reveals a good agreement for all the cases (the heavy, medium, and light fissioning nuclei). It is found out that the obtained dependence of sigma(2)(M) on l can be explained with the help of temperature at scission as a function of l. The latter dependence is determined by dependence of the mean prescission neutron multiplicity on l. The analysis of this dependence is done as a competition between fission process and neutron evaporation. Remembering of the former large fluctuations of mass asymmetry coordinate during descent from the saddle to scission is considered. It is shown that the remembering effect takes place, but does not play a crucial role for the investigated dependence of sigma(2)(M) on l. (c) 2005 Elsevier B.V. All rights reserved.