Search for closed-shell effects on the E2/M1 mixing of transitions in 116Sn

Directional-correlation measurements of several cascades in ¹¹⁶Sn have been made with a NaI-Ge(Li) detector system. Of particular interest in the 819-keV, $2^{{+}^{\prime }}$ → 2⁺ transition which was classified earlier as 90% E2 and almost pure M1 by two different groups. The γ-γ(θ) measurements of the $2^{{+}^{\prime }}$(819-keV) → 2⁺ (1293-keV) → 0⁺ cascade yield A₂ and A₄ coefficients of 0.31(2) and 0.27(5), respectively. From these data a δ(E2/M1) of -1.8(2) is obtained for the 819-keV transition, which corresponds to 76.4 ± 3.7% E2 radiation. The γ- ray intensities were measured more precisely.[RADIOACTIVITY ${}^{116}{In}^m$; measured γ-γ(θ), $I_{\gamma }$; deduced δ. NaI-Ge(Li) detectors.]