Nuclear reactions as an example of the quantum theory of irreversible processes

Abstract

A density matrix formalism is developed for nuclear reactions, where the nuclear system is described by an effective Hamiltonian in second quantisation, including potential scattering and different compound nucleus reactions. On the other hand, the nuclear system is coupled to reservoirs injecting and absorbing particles, such that the stationary solution of the irreversible density matrix equation describes a “fluxequilibrium”. Taking appropriate expectationvalues, the set of coupled equations is solved for potential scattering and especially for a compound nucleus reaction. The cross-sections are calculated, showing the Breit-Wigner resonance structure in the latter case, where the level width is expressed in terms of the matrix elements contained in the fundamental Hamiltonian.