Nuclear structure effects in bremsstrahlung

Abstract

The cross section for bremsstrahlung is calculated in the Born approximation, taking into account the emission by the nucleus of the bremsstrahlung photon, as well as the emission of the bremsstrahlung photon by the electron. The formal results, which are expressed in terms of various form factors, are applicable to an arbitrary nucleus. Nuclear matrix elements for the specific case of 16O are evaluated in the long wavelength limit, using the j− j coupling particle- hole model. Excited states included in evaluating the summations over intermediate nuclear states are limited to one-particle, one-hole configurations coupled by electric dipole transitions to the ground state. Effects in the bremsstrahlung spectrum due to the intrinsic structure of the 16O nucleus are found to be strikingly apparent, at least in the coincidence arrangement in which scattered electron and photon are observed simultaneously, in the form of peaks superimposed on the background from electron bremsstrahlung. The relative magnitude of the nuclear effects depends strongly on the scattering angles and on the photon energy, essentially a resonance effect, and varies over a wide range from one nuclear level to another.