The Angular Distributions of the Alpha-Particles and of the Gamma-Rays from the Disintegration of Fluorine by Protons

Abstract

The theoretical angular distributions of the alpha-particles and of the gamma-rays from the fluorine +proton reactions are given. They are compared with the experimental data, and the following results are obtained: (1) Both angular distributions of the ${\ensuremath{\alpha}}_{\ensuremath{\pi}}$-group and of the ${\ensuremath{\alpha}}_{0}$-group favor the assumption of even parity of ${\mathrm{F}}^{19}$. (2) If the parity of ${\mathrm{F}}^{19}$ is taken as even, then (a) the isotropic angular distribution of the gamma-rays at the resonances of 340 and 669 kev can be interpreted as due to the formation of ${\mathrm{Ne}}^{20}$ compound states of $J={1}^{+}$ by the capture of $s$-protons, (b) the slightly anisotropic angular distribution of the gamma-rays at the resonances of 598, 874, and 1381 kev can be interpreted as due to the formation of ${\mathrm{Ne}}^{20}$ states of $J={1}^{+}$ by a mixture of $s$- and $d$-protons, or of $J={2}^{\ensuremath{-}}$ by $p$-protons, (c) the highly anisotropic distribution of the gamma-rays observed at 1290 and 1355 kev can be interpreted as due to the formation of ${\mathrm{Ne}}^{20}$ states of $J={3}^{+}$, and (d) the experimental data of the gamma-ray angular distribution and of the ratio $\frac{{I(\ensuremath{\alpha})}_{140\ifmmode^\circ\else\textdegree\fi{}}}{{I(\ensuremath{\gamma})}_{90\ifmmode^\circ\else\textdegree\fi{}}}$ are compatible with the assignment ${j}^{\ensuremath{'}}={3}^{\ensuremath{-}}$ for the ${\ensuremath{\gamma}}_{1}$-level of ${\mathrm{O}}^{16}$. In general it is possible to make spectroscopic assignments consistent with the experimental data but unique assignments will await further experimental results.