Classical photon production in neutron-proton collisions

The classical theory of bremsstrahlung is applied to neutron-proton scattering in order to obtain the elementary photon-production cross section. The so-called ''internal radiation'' from the Feynman diagrams is classically evaluated in the charged one-pion exchange hypothesis. The introduction of such a contribution produces a substantial enhancement of the pnγ yield for photon energies higher than 30 MeV. The results are compared with quantum calculations, which use a parametrization of the nucleon-nucleon T-matrix in terms of OBE amplitudes and with few available experimental bremsstrahlung data. ((orig.))