Constraining presaddle dissipation with fission cross sections of light nuclear systems

Nuclear fission is hindered by dissipation. Based on the stochastic Langevin model, we calculate the drop of fission cross section caused by friction with respect to its standard statistical-model value, σfᵈʳᵒᵖ, as a function of the presaddle friction strength (β) for fissioning nuclei ²⁰⁵Bi, ²¹⁵Fr, ²²⁵Pa, and ²³⁰Np at different angular momenta and excitation energies. It is found that with increasing the size of fissioning systems, the sensitivity of σfᵈʳᵒᵖ to β is reduced substantially, and it disappears for the ²³⁰Np system. Our findings suggest that on the experimental side, to more stringently constrain the presaddle dissipation strength by measuring fission excitation functions, it is optimal to yield those fissioning systems with a small size.