Single Frenkel-Pair Production by Neutrino Recoil

Abstract

The decay of $^{111}\mathrm{Sn}$ to $^{111}\mathrm{In}$ via electron capture is employed for the first observation of a solid-state effect caused by nuclear recoil due to neutrino emission. The monoenergetic $^{111}\mathrm{In}$ recoil atoms of 29 eV start from substitutional lattice sites in copper and produce isolated, single Frenkel pairs. The effect is traced by observation of $\ensuremath{\gamma}\ensuremath{\gamma}$ perturbed angular correlations following the decay $^{111}\mathrm{In}$ to $^{111}\mathrm{Cd}$.