Precise measurements of lifetimes and deorientation in $^{92,94}$Zr using the Recoil Distance Doppler Shift method

The lifetime for the $2_{1}^{+}$ state in $^{94}$Zr is known with only 20\% accuracy. In this region, involving proton and neutron sub-shell closures, it is highly desirable to know this value to greater precision, especially since $^{94}$Zr has the extraordinary case where the E2 excitation strength of the $2_{2}^{+}$ appears to be greater than that of the $2_{1}^{+}$. Therefore, we performed a lifetime measurement using the Recoil Distance Doppler Shift (RDDS) method and the New Yale Plunger Device. Beams of $^{92,94}$Zr, at energies of 245 MeV and 250 MeV, respectively, were Coulomb excited on a $^{24}$Mg target and $\gamma$-rays were measured in coincidence with the forward scattered Mg ions. Nuclear deorientation effects, due to hyperfine interactions, become increasingly important at the high charge states of the recoiling ions. In parallel to the RDDS measurement, the attenuation coefficients of the angular distributions were measured. The time dependence of these coefficients was used to calculate relative magnetic moments.