Gamma-Ray Production Cross Sections of Neutron-Induced Reactions in Oxygen

Abstract

The gamma-ray production cross section of oxygen has been measured at incident neutron energies between 7 and 10.5 MeV. The production of the 6.13-, 6.92-, and 7.12-MeV gamma rays by the (n,n′γ) reaction in 16O and the 3.09-, 3.68-, and 3.85-MeV gamma rays by the (n,αγ) reaction has been studied. In addition, the production cross section of the 4.44-MeV gamma ray from inelastic neutron scattering on carbon has been measured at one neutron energy, since many earlier measurements of gamma-ray production cross sections have been performed relative to this cross section. Monoenergetic neutrons were produced by the 2H(d,n)3He and 3H(p,n)3He reactions. The gamma radiation was detected by a large Nal(Tl) scintillator using time-of-flight techniques. The neutron flux was measured by means of a proton-recoil telescope using the n-p scattering cross section. The differential gamma-ray production cross sections were measured at 90 deg. In addition, the angular distribution for the 6.13-MeV gamma ray was determined at one neutron energy. The results for oxygen, which show pronounced structure of the cross section for the 6.13-MeV gamma ray over the whole energy region, are in disagreement with current data files, whereas the results for carbon are in agreement with a number of recent investigations of the 12C(n,n′γ)12C and 12C(n,n′)12C reactions.