Photoprotons from Oxygen

Abstract

The cross section and angular distribution of the ${\mathrm{O}}^{16}(\gamma , p){\mathrm{N}}^{15}$ reaction have been obtained for photon energies between 13.5 and 18.7 Mev, i.e., below the expected position of the giant resonance. The angular distribution indicated that the reaction proceeded predominantly through electric quadrupole or magnetic dipole absorption of photons, even though electric dipole transitions are allowed by isotopic spin selection rules. Suggestions are made regarding this forbiddenness of electric dipole absorption.