Scattering of 64.3-MeV Alpha Particles from Nickel-58 and Iron-58

Abstract

For 64.3-MeV $\alpha$ particles the differential cross sections for elastic scattering and excitation of the first $2^{+}$ collective state have been measured for the ${\mathrm{Ni}}^{58}$ and ${\mathrm{Fe}}^{58}$ isobars at approximately 0.5° intervals between 10° and 82° in the center-of-mass system. The measurements were made with sufficient precision to follow the rapid variations and deep minima in the angular distributions, and the data have been exhaustively studied for possible errors; an extensive discussion of the uncertainties is given. An analyzed beam (energy spread ${\mathrm{Fe}}^{58}$, about half as intense as from ${\mathrm{Ni}}^{58}$, can be qualitatively described by using a deeper absorptive potential for ${\mathrm{Fe}}^{58}$. Analysis of the elastic- and inelastic-scattering cross sections for ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}<50\mathrm{}°$ using the smooth cutoff model of Blair, Sharp, and Wilets gives the quadrupole deformation parameter $\beta$ as 0.15 (${\mathrm{Ni}}^{58}$) and 0.17 (${\mathrm{Fe}}^{58}$).