Straight-Back Elastic Alpha Scattering fromTi48,Cr52,Cr53, andNi58

Abstract

Cross sections are reported for $\alpha$ particles scattered from ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$. For the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ target, both elastic and inelastic (to the first excited state) data are presented for $\alpha$ particles of 12 incident energies between 13 and 29 MeV scattered into the angular range from 152° through 180° to -172°. Elastic excitation functions at 180° are given for $\alpha$ particles of six energies between 20 and 29 MeV scattered from ${}_{}{}^{52}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{53}{}_{}{}^{}\mathrm{Cr}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$. The elastic angular distributions exhibit a narrow "glory peak" at 180° for each energy, and the peak cross section at 180° is sensitively dependent on both the bombarding energy and the target mass. For the case of ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, the measured elastic cross sections at 180° are about an order of magnitude larger than values predicted from optical-model calculations with a potential that fits $\alpha$ scattering data forward of 140°.