Backstreaming effects on probing postsaddle dissipation with light particle multiplicity

Abstract

Nuclear dissipation retards fission. Using the stochastic Langevin model, we study pre- and post-saddle emitted neutrons, protons and α particles of heavy 245Cf nuclei as a function of the postsaddle dissipation strength (β) in the absence and presence of backstreaming around the saddle point. It is shown that the backstreaming effects (BEs) cause the fissioning system to return back inside saddle, which increases presaddle light particles but decreases postsaddle emission. Moreover, the BEs on pre- and post-saddle evaporation are found to become greater with increasing β and excitation energy. These findings demonstrate a significant role of BEs in tightly constraining the postsaddle dissipation strength with light particle multiplicity. Furthermore, we analyze the measured prescission neutron number in the reaction 16O (Elab=104 MeV) +232Th ⟶248Cf, and find that, after accounting for the BEs, the best-fit value of the β required to satisfactorily describe the experimental data changes from 9.6 ×1021 s−1 to 6×1021 s−1, showing a strong influence of backstreaming on accurately probing the postsaddle dissipation strength.