Activation Cross Sections of Germanium for 14.4-MeV Neutrons

Abstract

${\mathrm{Ge}}^{69,75}$, ${\mathrm{Ga}}^{72,73,74}$, and ${\mathrm{Zn}}^{60m,71m}$ were produced by irradiating natural germanium with 14.4±0.3-MeV neutrons. Two mixtures of powders containing Ge${\mathrm{O}}_2$+Al+Fe and Ge${\mathrm{O}}_2$+Al+Cu also were irradiated. The activities were identified from gamma spectra taken with a Ge(Li) detector and the cross sections were measured using the improved technique described by Rao and Fink. The reactions for which cross sections were measured are: ${\mathrm{Ge}}^{70}(n, 2n){\mathrm{Ge}}^{69}$, 447±45 mb; ${\mathrm{Ge}}^{76}(n, 2n){\mathrm{Ge}}^{75}$, 1236±120 mb; ${\mathrm{Ge}}^{72}(n, p){\mathrm{Ga}}^{72}$, 47.4±4.7 mb; ${\mathrm{Ge}}^{73}(n, p){\mathrm{Ga}}^{73}$, 26.4±2.6 mb; ${\mathrm{Ge}}^{74}(n, p){\mathrm{Ga}}^{74}$, 13.2±1.3 mb; ${\mathrm{Ge}}^{72}(n, \alpha ){\mathrm{Zn}}^{69m+g}$, 15.2±1.5 mb; and ${\mathrm{Ge}}^{74}(n, \alpha ){\mathrm{Zn}}^{71m+g}$, 13.3±1.3 mb. For all cases where isomers exist, the cross-section value is total for $m+g$. The ${\mathrm{Ge}}^{76}(n, 2n){\mathrm{Ge}}^{75}$ (82-min) cross section also was checked by beta counting, which is independent of decay-scheme assumptions. The results are compared with the systematics of ($n, 2n$), ($n, p$), and ($n, \alpha$) cross sections at 14-15 MeV.