Coulomb excitation of vibrational states in Th-232 with O-16 projectiles -art. no. 064602

Excited states in Th-232 were populated by Coulomb excitation with 80MeV O- 16 ions. Gamma-gamma coincidences were detected with the detector array YRA ST Ball. The one-phonon quadrupole and octupole vibrations are most strongl y excited. These vibrations are in Th-232, particularly favorable cases for a study of their couplings, due to the small energy spacings of the beta a nd gamma bands and the K-pi=1(-) and 2(-) bands, respectively. The need for additional experimental information on the gamma-ray intensities and the l ocation of members of the octupole-vibrational bands is emphasized. The hig her-lying K-pi=0(+) bands with bandheads at 1079 and 1352 keV proposed prev iously are observed and some conflicting properties of these bands are disc ussed. The interpretation of the 1352 keV 0(+) band as two-octupole-phonon vibration is not supported by our data. A level at 1054 keV, previously ass igned as 2(+) or 2(-) level, is tentatively proposed to be the bandhead of a second-excited K-pi=2(+) band. Our gamma gamma coincidence data establish that the unusually enhanced E2 transitions from a 2(+) level at 1554 keV t o members of the beta and gamma bands proposed previously do not exist.