Dynamical model of surrogate reactions

Aritomo, Yoshihiro; Chiba, Satoshi; Nishio, Katsuhisa   

A new dynamical model is developed to describe the whole process of surrogate reactions; the transfer of several nucleons at an initial stage, thermal equilibration of residues leading to washing out of shell effects and decay of populated compound nuclei are treated in a unified framework. Multi-dimensional Langevin equations are employed to describe time-evolution of the system. The new model is capable of calculating the spin distribution of the compound nuclei, one of the most important quantities in the surrogate technique. Furthermore, observable of surrogate reactions can be calculated. It is found that spin distributions of compound nuclei produced in O+U O+U reactions are equivalent and much less than 10, therefore satisfy conditions proposed by Chiba and Iwamoto if they are used as a pair in the surrogate ratio method.