Angular Distributions ofαParticles from theNa23(p, α)Ne20Reaction

Abstract

The angular distribution of $\alpha$ particles produced by the ${\mathrm{Na}}^{23}(p, \alpha ){\mathrm{Ne}}^{20}$ reaction and leading to the ground state of the residual ${\mathrm{Ne}}^{20}$ nucleus has been measured at six resonances occurring in the region $E_p=1\mathrm{} \mathrm{to} 2$ Mev. The measured distributions are compared to the calculated angular distributions. In many cases the calculated angular distribution for a given type of compound state is not unique in that an unknown mixture of channel spins enters as well as possible admixtures of higher $l$ values. The best assignments for the resonances at 1.137, 1.012, and 1.166 Mev are respectively $0^{+}$, $3^{-}$, and $2^{+}$. A large anisotropy is observed for the resonance at 1.288 Mev which is not predicted by any simple assignment. It can, however, be fitted by a $1^{-}$ assignment in which there is a rather large admixture of $f$-wave to the $p$-wave protons. The resonance at 1.804 Mev is found to be complex.