Resonant rate for 15O( alpha, gamma )19Ne.

Abstract

We have measured angular distributions for the ${}^{15}\mathrm{N}{(}^{6}\mathrm{Li},d{)}^{19}$F and ${}^{16}\mathrm{O}{(}^{6}\mathrm{Li},d{)}^{20}$Ne reactions at a bombarding energy of 22 MeV. Distorted-wave Born-approximation and Hauser-Feshbach calculations were used to analyze the data. Ratios of $\ensuremath{\alpha}$-transfer cross sections in ${}^{19}\mathrm{F}$ and ${}^{20}$Ne, plus isospin invariance, provide ratios of $\ensuremath{\alpha}$ widths in ${}^{19}$Ne and ${}^{20}$Ne. Using ${}^{20}$Ne ( ${1}^{\ensuremath{-}}$, 5.788 MeV) as a standard allows the determination of the $\ensuremath{\alpha}$-particle width for the state at 4.033 MeV in ${}^{19}$Ne, and hence the resonant rate for the ${}^{15}$O $(\ensuremath{\alpha},\ensuremath{\gamma}{)}^{19}$Ne reaction, contributed from the 504 keV, ${\frac{3}{2}}^{+}$ resonance, at temperatures of astrophysical interest.