Energy Levels inF18from Alpha-Particle Reactions in Nitrogen

Abstract

We have examined both the elastic scattering of alpha particles in nitrogen as a function of the energy between 1.5 and 3.5 Mev at 90°, 125°16′, 137°43′ and 156°20′ (center of mass), and the cross section for the ${\mathrm{N}}^{14}(\alpha , p){\mathrm{O}}^{17}$ reaction at 90° (lab) in the same energy region. Two new resonances at $E_{\alpha }=2.935\mathrm{}$ Mev and $E_{\alpha }=3.140\mathrm{}$ Mev correspond to levels in ${\mathrm{F}}^{18}$ at excitation energies of 6.69 Mev and 6.85 Mev, respectively. These same levels were found to emit protons as well, leading to the ground state of ${\mathrm{O}}^{17}$. The ($\alpha , p$) reaction has a relative probability of about 5 percent for the upper level and 0.3 percent for the lower level, compared to the elastic scattering.