Radiative strength functions of germanium from thermal neutron capture

Thermal neutron capture gamma rays from germanium have been studied using an internal irradiation facility and a pair spectrometer. Energy and intensity of transitions in four germanium isotopes were determined and their level and separation energies inferred. The separation energies are ${\mathit{S}}_{\mathit{n}}$ ${(}^{71}$Ge)=7415.95±0.05 keV, ${\mathit{S}}_{\mathit{n}}$ ${(}^{73}$Ge)=6782.94±0.05 keV, ${\mathit{S}}_{\mathit{n}}$ ${(}^{74}$Ge)=10 196.31±0.07 keV, and ${\mathit{S}}_{\mathit{n}}$ ${(}^{75}$Ge)=6505.26±0.08 keV. The E1 reduced strength function, 〈${\mathrm{\Gamma }}_{\gamma \mathit{i}}$ ${\mathit{D}}^{\mathrm{-}1}$ ${\mathit{E}}_{\mathit{i}}^{\mathrm{-}3}$ ${\mathit{A}}^{\mathrm{-}2/3}$〉, of these germanium isotopes was found to be (1.8±0.5)×${10}^{\mathrm{-}9}$ ${\mathrm{MeV}}^{\mathrm{-}3}$, a value lower than the global average. The M1 strength function 〈${\mathrm{\Gamma }}_{\gamma \mathit{i}}$ ${\mathit{D}}^{\mathrm{-}1}$ ${\mathit{E}}_{\mathit{i}}^{\mathrm{-}3}$〉 of ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$ was estimated to be (20±9)×${10}^{\mathrm{-}9}$ ${\mathrm{MeV}}^{\mathrm{-}3}$ which agrees with the global average. The average B(E2)↓¯ of ${}_{}{}^{74}{}_{}{}^{}\mathrm{Ge}$ using the present thermal data and the previous resonance data from literature was found to be 18±10${\mathit{e}}^2$ ${\mathrm{fm}}^4$ MeV ${}_{}{}^{\mathrm{-}1}{}_{}{}^{}$ which agrees with the value predicted by the Axel-Brink hypothesis.