Directional Correlation of Gamma Rays in the Decay of 2·3 d 115Cd

Abstract

The gamma-gamma directional correlation of the 35-493 keY cascade in the decay of 2·3 d 116Cd has been studied by the coincidence method. The results seem to favour the spin and parity assignments 1/.+, 3/.+, and 1/.- for the levels at 864, 829, and 336 keY respectively, and indicate that the 35 keY transition is (96·5±0·5)% Ml and (3·5±0·5)% E2, with a mixing parameter 8 = -0·191± 0·014. These results agree with the recent I.C.C. measurements of Backlin, Fogelberg, and Malmskog but differ from those of earlier work. Computation of the partial lifetimes of the 35 keY radiation on this basis indicates that the Ml transition is retarded by a factor of ~ 23 and the E2 transition is enhanced by a factor of ~ 958. The E 1 component of 493 ke V radiation is estimated to be hindered by a factor of ~ 4 X 10-7, while the M2 component is retarded by a factor of ~ 3. The possible collective nature of the 829 keY level is discussed.