The Scattering of Alpha-Particles by Argon, Oxygen and Neon

Abstract

Data on the scattering of alpha-particles by argon, oxygen and neon have been obtained with a novel experimental arrangement developed for the purpose. Anomalies were found in the scattering by all three elements. Irregularities in the course of the anomalies in the cases of oxygen and neon have been interpreted as resonance phenomena. Estimates of the radii of the various nuclear barriers, based on the assumption that the penetrability of the barrier is appreciable at the lowest energy for which an anomaly is apparent, give the values ${4.5(10}^{-13\mathrm{}}$) cm for ${\mathrm{O}}^{16}$, ${4.6(10}^{-13\mathrm{}}$) cm for ${\mathrm{Ne}}^{20}$, and ${7.5(10}^{-13\mathrm{}}$) cm for ${\mathrm{A}}^{40}$. The first two are lower than values calculated from the formula $R=2.05\left({10}^{-13\mathrm{}}\right){\mathrm{A}}^{\frac{1}{3}}$ and the last is somewhat higher. The latter result agrees with deductions of Pollard, Schultz, and Brubaker from data on the $\mathrm{A}-\alpha -n$ reaction.