The neutron-capture cross sections of ${}^{64}$Zn, ${}^{68}$Zn, and ${}^{70}$Zn have been measured with the activation technique in a quasistellar neutron spectrum corresponding to a thermal energy of $kT=25$ keV. By a series of repeated irradiations with different experimental conditions, an uncertainty of 3$\%$ could be achieved for the ${}^{64}$Zn($n,\gamma$)${}^{65}$Zn cross section and for the partial cross section ${}^{68}$Zn($n,\gamma$)${}^{69}$Zn${}^m$ feeding the isomeric state in ${}^{69}$Zn. For the partial cross sections ${}^{70}$Zn($n,\gamma$)${}^{71}$Zn${}^m$ and ${}^{70}$Zn($n,\gamma$)${}^{71}$Zn${}^g$, which had not been measured so far, uncertainties of only 16$\%$ and 6$\%$ could be reached because of limited counting statistics and decay intensities. Compared to previous measurements on ${}^{64,68}$Zn, the uncertainties could be significantly improved, while the ${}^{70}$Zn cross section was found to be two times smaller than existing model calculations. From these results Maxwellian average cross sections were determined between 5 and 100 keV. Additionally, the $\beta$-decay half-life of ${}^{71}$Zn${}^m$ could be determined with significantly improved accuracy. The consequences of these data have been studied by network calculations for convective core He burning and convective shell C burning in massive stars.

• Received 22 December 2011

DOI:https://doi.org/10.1103/PhysRevC.85.035802