Radiative capture by 19F: The giant dipole resonances in 20Ne

Abstract

The radiative capture of protons by 19F has been studied over the range of proton bombarding energies from 2.88 MeV to 12.80 MeV. The most intense capture gamma rays are γ 0 to the ground state and γ 1 to the first excited state in 20Ne. The yield curves for both γ 0 and γ 1 are dominated by the E1 giant resonance with the γ 1 giant resonance displaced upward in excitation energy from the γ 0 giant resonance. Strong, well correlated structure is present in the yield curves; the structure has a characteristic width of about 175 keV. Extensive angular-distribution measurements showed that the angular distributions do not vary greatly with energy. The angular distributions are incompatible with γ 0 and γ 1 emanating from the same levels of the compound nucleus. The integrated yields, structure and angular distributions are compared with the results of other (p, γ) studies of the E1 giant resonance and some of the features of this and other radiative-capture experiments are discussed in terms of the shell model.