Cold events in thermal-neutron-induced fission of heavy nuclei

An interpretation of the cold fission events in thermal-neutron-induced fission of heavy nuclei is given. The descent from the saddle point is considered as a dynamical process with reversible coupling between collective and intrinsic degrees of freedom. The distribution function for the collective variables is expressed as a product of two terms: the adiabatical and the dynamical factors. A simple model for symmetric fission to study the mass distribution is presented. As example, the calculations are performed for the nucleus ²⁶⁴Fm. Gross features of the cold fission are discussed as well as the dependence of the theoretical mass distribution on the parameters of the model. Received: 29 April 1998 / Revised version: 11 September 1998