Inclusive γ and π0 cross sections in heavy-ion reactions

Perturbation theory in a time-dependent basis is used to derive formal expressions for pion and gamma emission in heavy-ion reactions. The structure of the theory motivates an external mean-field phenomenology as a representation of the actual mean field plus lowest-order collision dynamics. The source function for the emission process is identified as a Wigner function constructed from the time Fourier transform of the nuclear wavefunctions. A simple model of the Wigner function is constructed and used to relate the production cross section for πsup(0) and γ in the reaction 14N + Ni at a laboratory bombarding energy per nucleon of 35 MeV. A direct relation between π0 and γ cross sections is predicted to hold in the region of high gamma ray energy where the gamma emission is dominated by spin currents. (author)