Neutron multiplicities in fission viewed as a diffusion process

Using a diffusion model for the fission process and a simple cascade scheme for the de-excitation of the compound nucleus, we show that multiplicities of pre-fission neutrons depend sensitively on the nuclear friction β. With respect to predictions of the statistical model, enhancement by factors 2 to 5 are obtained in the excitation energy range 100 to 200 MeV, depending on the value of β. (orig.)