Nuclear fission is hindered by dissipation. Using the stochastic Langevin model, we study postsaddle emitted neutrons, protons, and $\alpha$ particles of heavy ${}^{240}\mathrm{Am}$ nuclei as a function of postsaddle dissipation strength $\left(\beta \right)$ at different excitation energies and angular momenta. It is shown that the sensitivity of these particles to $\beta$ is significantly enhanced at a high energy and a large angular momentum. Furthermore, we calculate the evolution of postsaddle particles with $\beta$ under two contrasting initial conditions for the produced heavy nuclei ${}^{240}\mathrm{Am}$: (i) high excitation energy but low angular momentum (available in intermediate-energy heavy-ion collisions) and (ii) low excitation energy but high angular momentum (available via fusion reactions). We find that the former type of conditions not only significantly enhances the influence of dissipation on particle evaporation but also substantially increases the sensitivity of light charged particles to $\beta$. Our findings suggest that on the experimental side, to accurately probe postsaddle dissipation strength by measuring particle emission, in particular light charged particle multiplicity, it is optimal to choose the intermediate-energy heavy-ion collision approach as a way to populate excited heavy nuclear systems.

• Received 30 June 2018
• Revised 30 August 2018

DOI:https://doi.org/10.1103/PhysRevC.98.034614