Direct-Interaction (p,α) Reactions inY89andZr90

Abstract

Alpha-particle energy spectra from ($p,\alpha$) reactions in ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$ and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ were obtained at 5-deg intervals between 15 and 90 deg. Bombarding energies of 20.2 and 22.5 MeV were used. Differential cross sections for reactions leading to the ground states and first excited states were determined. Distorted-wave calculations were done for the angular distributions for the reactions leading to each of the ground states and the 0.38-MeV first excited state in ${}_{}{}^{87}{}_{}{}^{}\mathrm{Y}$. The calculated angular distributions reproduce the general features of the experimental angular distributions. Spectroscopic factors, obtained from normalization of the calculated angular distributions to the experimental data, are consistent with triton pickup as the dominant mechanism for direct-interaction ($p,\alpha$) reactions. The normalization factors also indicate the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ ground-state proton configuration to be 70% ${\left(2\mathrm{}{p}_{\frac{1}{2}}\right)}^2$ and 30% ${\left(1\mathrm{}{g}_{\frac{9}{2}}\right)}^2$.