Hyperfine fields at Ga66 , Ge67,69 implanted into iron and gadolinium hosts at 6 K, and applications to g -factor measurements

Abstract

Isomers in $^{66}\mathrm{Ga}$, $^{67}\mathrm{Ge}$, and $^{69}\mathrm{Ge}$ were recoil implanted into ferromagnetic hosts of iron and gadolinium at $\ensuremath{\approx}6$ K, and the hyperfine magnetic fields were determined by time differential perturbed angular distribution (TDPAD) measurements. The hyperfine field strengths at $\ensuremath{\approx}6$ K are compared to the results of previous higher-temperature measurements and the amplitudes of the $R(t)$ functions are compared to empirical expectations. The results show that gadolinium can be a suitable host for high-precision in-beam $g$-factor measurements. The results of new $g$-factor measurements for isomers in $^{66}\mathrm{Ga}$ and $^{67}\mathrm{Ge}$ are $g(^{66}\mathrm{Ga}, {7}^{\ensuremath{-}})=+0.126(4)$, supporting a ${[{\ensuremath{\pi}}_{f5/2}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{9/2}]}_{{7}^{\ensuremath{-}}}$ configuration assignment, and $g(^{67}\mathrm{Ge}, 9/{2}^{+})=\ensuremath{-}0.1932(22)$, derived from a new measurement of the ratio $g{(}^{67}\mathrm{Ge})/g{(}^{69}\mathrm{Ge})=0.869(9)$. These values are in agreement with previous results. The $R(t)$ amplitudes indicate that the nuclear alignment produced in the isomeric states was significantly lower than the empirically expected $\ensuremath{\sigma}/I\ensuremath{\approx}0.35$.