High-energy photons in neutron-proton and proton-nucleus collisions

K. Nakayama
Phys. Rev. C 39, 1475 – Published 1 April 1989
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Abstract

In an effort to better understand the dynamics of nucleon-nucleon bremsstrahlung in producing energetic photons, we have investigated the contribution of each part of the current associated with the different terms in the nuclear Hamiltonian to the neutron-proton bremsstrahlung cross sections. In the range of photon energy investigated here, we find meson-exchange currents to be the dominant source of high-energy photons (ω≳50 MeV). Although the one-body current contribution is small for such energetic photons, its interference with the two-body current is important and enhances the cross section. At low photon energy the convection current dominates. We find that the bremsstrahlung cross section is very sensitive to the 3(SD)1 states and offers a potential means of investigating short-range correlation effects. Off-energy-shell effects are estimated to have only a small influence on the neutron-proton bremsstrahlung inclusive cross section. In connection with the neutron-proton bremsstrahlung process, the nucleon-nucleon collisional mechanism in producing high-energy photons in proton-induced reactions has been also investigated within the nuclear matter approximation. Nuclear medium effects in intermediate states are shown to have a minor influence on the photon cross section; therefore, the use of a free nucleon-nucleon T matrix instead of a G matrix seems to be well justified. However, the results are found to be very sensitive to medium effects in the initial and final states.

  • Received 11 July 1988

DOI:https://doi.org/10.1103/PhysRevC.39.1475

©1989 American Physical Society

Authors & Affiliations

K. Nakayama

  • Department of Physics and Astronomy, University of Georgia, Athens, Georgia 30602

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Vol. 39, Iss. 4 — April 1989

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