SEMICLASSICAL APPROACH TO THE DESCRIPTION OF NUCLEAR-REACTIONS WITH FAST PARTICLES

An approach to the description of nuclear reactions has been formulated based on the solution of the Dyson equations for the single-particle Green functions and the separation of the particle-nucleus interaction processes into coherent and incoherent parts. It is shown that in the quasiclassical approximation this approach admits a kinetic interpretation. In this case, to describe nuclear reactions, we can use generalized Boltzmann equations for the Green functions, these equations being a self-consistent generalization of the classical kinetic equation for the distribution function. An algorithm of the solution of the generalized Boltzmann equations is proposed which allows us to take into account nonlocal features of the interaction of fast particles with nuclei, i.e. the dependence of the mass operator on energy and momentum. The mean free paths of pions and nucleons in nuclei, l, obtained by means of this method, agree with the results of the analysis of experimental data in the framework of various phenomenological models. It is shown that within the limits of accuracy defined by the parameter #38; {combining short stroke overlay}lambda;/l ( #38; {combining short stroke overlay}lambda; the de Broglie wavelength of the particles involved) the quasiclassical approach allows us to describe both nuclear reactions with nucleons having energy below the threshold of pion production, and the processes involving pions without any free parameters. This fact allows us to analyze various processes such as inelastic interaction of pions with nuclei, processes of pion production and subthreshold kaon production in proton-nucleus collisions, and nuclear reactions with cumulative particle production. The possible expansions of this method are discussed. © 1990.