Search for transient electric field gradients acting on fast-moving ions in solids

In an attempt to explore a possible new technique for the measurement of quadrupole moments of short-lived states, we have searched for an internal quadrupole field induced by a possible transient electric field gradient acting on fast-moving ions in solids. In the measurement we attempted to detect perturbations of the angular correlation pattern of $\gamma$ rays deexciting the first $2^{+}$ states in ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, which were both Coulomb excited in the interaction of 125-MeV ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ with ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$. No electric field gradient effect was seen (≤${10}^{21}$ V/${\mathrm{cm}}^2$). As a by-product, some information was obtained on vacuum deorientation coefficients for ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$.