ELECTRON-CAPTURE DECAY OF GADOLINIUM-151

The photon and conversion electron spectra following electron-capture decay of Gd/sup 151/ were studied. Transitions of 21.59 (M1), 153.7, 175.0 (M2), 243.8 (E1), and 308.4 kev seen in these spectra and a very weak transitlon of 155 plus or minus 5 kev seen in coincidence with the 153.7-kev transition were assigned to the decay of Gd/sup 151/. Relative photon, conversionelectron, and transition intensities were determined for some of the transitions, and coincidence measurements were made at resolving times of 4 and 40 microseconds. The 175. 0-kev transition was observed to depopulate a metastable state with a half-life of 58 plus or minus 10 microseconds. A level scheme is proposed for Eu/sup 151/ including the levels populated by Coulomb excitation, BETA /sup -/ decay of Sm/sup 151/, and electron-capture decay of Gd/sup 151/. (auth)