EXPERIMENTAL INVESTIGATION OF VIBRATIONAL EXCITATIONS IN TH-230

Nuclear levels in Th-230 have been investigated in the beta decay of 2 30Pa, the Th-230(d, pn gamma) reaction and the Th-232 (p, t) reaction. The K(pi) = 0(1)+, 2(1)+, and 2(2)+ bands with band heads at 635, 781 , and 1010 keV were observed up to the 8+, 9+, and 7+ levels, respecti vely. A second excited 0+ level was identified at 1297 keV which might be interpreted as the usual beta shape-oscillation. The branching rat ios of the E2 transitions from the 0(1)+, 2(1)+, and 2(2)+ bands are e xplained in the framework of the rotational model by taking into accou nt the coupling of these bands with the ground-state band, and the cou pling between the 0(1)+ and 2(1)+ band. A strong enhancement of E2 tra nsitions from the 2(1)+ to the 0(1)+ band reported earlier is not conf irmed. For the octupole vibrations with K(pi) = 0-, 1-, and 2- the E1 branching ratios are analyzed in terms of the Coriolis coupling of the se bands. An almost complete experimental set of E1 transition moments from these negative-parity bands to the 0g+, 0(1)+, and 2(1)+ bands w as obtained. It is suggested that octupole correlations might be impor tant in explaining these E1 moments.