The Photodisintegration of Nitrogen

Abstract

The (γ, p), (γ, pn), (γ, α), (γ, αα) and (γ, αp) reactions in 14N have been studied by passing the X-ray beam from a 23 MeV synchrotron through a Wilson cloud chamber. The range distribution of protons of energy up to 3 MeV shows sharp well-defined peaks at energies of 0.51, 1.63 and 2.92 MeV. These energies correspond closely to the energies of the resonances reported for the 13C(p, γ)14N (ground state) reaction. For these resonances the ratios of the cross sections for the (γ, p) and (p, γ) reactions are in good agreement with the predictions of the principle of detailed balancing. At higher energies the following measurements were made: (i) the (γ, p) process was investigated by measuring the range distribution of the 13C nuclei, (ii) both (γ, p) and (γ, pn) processes were studied by measuring the numbers of events at three different synchrotron peak energies. These measurements showed that both the (γ, p) and (γ, pn) cross sections are small at energies up to 15 MeV and large in neighbourhood of 20 MeV. The estimated values of the integrated cross sections up to 23 MeV for the (γ, p) and the (γ, pn) reactions are both approximately 0.02 MeV barn. The (γ, α), (γ, αα) and (γ, αp) cross sections are each about 0.1 millibarn. The implications of these results are discussed in some detail.