Atomic effects in nuclear reactions

The dependence of nuclear reaction observables on excitation of the surrounding atom is developed in a systematic way. Considerations are confined to those excitations of the atomic electrons arising from changes in the nuclear charge and velocity as a result of the nuclear reaction. The analysis is divided into two distinct parts. In the first, a general time-dependent semiclassical formalism of atomic excitation as a result of a nuclear reaction is derived and sum rules for the moments of the electron excitation-energy distribution are obtained. Reasonable procedures for modifying nuclear reaction observables by atomic transition amplitudes and energies are applied to calculate atomic corrections to Q values in #betta#+ decay, (p,n) threshold, and (3He,t) reactions, as well as to an analysis of a nuclear resonance reaction. In the second part, a time-independent R-matrix theory is developed and the dependence on atomic excitation of quantities characterizing a nuclear reaction is derived. The R-matrix formalism, generalized to include atomic excitation, retains all the utility of the usual nuclear R-matrix theory. The results of the second part are applied to an analysis of resonant elastic scattering in 4He(α,α)4He