Directional correlations of gamma rays in 152Sm and 152Gd measured by means of two Ge(Li) counters

Abstract

Directional correlation measurements have been performed with two Ge(Li) counters on several γ rays in coincidence with the 121.78 and 334.31 keV γ transitions which de-excite the first 2+ levels in 152Sm and 152Gd, respectively. A total of 20 γ−γ directional correlations, 13 in the 152Sm nucleus and 7 in the 152Gd nucleus, was measured simultaneously. Several of the γ−γ directional correlations involved gamma transitions of weak intensity, for example the (688.66−121.78), (1457.4−121.78), and (1528.16−121.78) keV cascades in 152Sm and the (586.29−334.31) and (1089.73−334.31) keV cascades in 152Gd. Among the various results which could be extracted from these measurements, the most interesting appears to be the determination of a nearly pure E2 character for the 688.66, 964.01, 1112.04, and 867.33 keV gamma transitions. The first two γ rays de-excite the 2+ β- and γ-vibrational levels to the 2+ ground-state rotational level at 121.78 keV in 152Sm, whereas the last two γ rays de-excite the3+ γ-vibrational level to the 2+ and 4+ (at 366.44 keV) ground-state rotational levels in 152Sm.