Reactions with Protons on Nitrogen

Abstract

The yields and angular distributions of the charged particles produced on bombardment of nitrogen by protons have been studied in the range of 6- to 9-MeV incident proton energy. The cross section of the ($p,\ensuremath{\alpha}$) reaction is much larger than that of the reaction producing$\phantom{\rule{0ex}{0ex}}^{3}\mathrm{He}$ or inelastic scattering of protons to the first four excited states of $^{14}\mathrm{N}$. A broad resonance (roughly 800 keV in width) was found in the ($p,\ensuremath{\alpha}$) reaction centered at a proton bombarding energy of 7.5 MeV. The angular distribution of the ${p}_{1}$ proton group (leading to the first excited state of $^{14}\mathrm{N}$) shows that the spin and parity of this resonant state is ${\frac{3}{2}}^{\ensuremath{-}}$. There is evidence for an additional broad ${\frac{3}{2}}^{+}$ state centered at 6.6 MeV. Sharp resonances appear superposed on these broad resonances in the ($p,\ensuremath{\alpha}$) reaction; for most of these the $\ensuremath{\alpha}$-particle yield is much larger than the proton yield. Some sharp resonances appear only in the ($p,\ensuremath{\alpha}$) reaction. The reduced $\ensuremath{\alpha}$-particle widths are usually of the order of a few percent of the Wigner limit, and 10 times higher than the reduced widths to the Wigner limit for neutron and proton emission.