Octupole correlations in neutron-rich Ba-143,Ba-145 and a type of superdeformed band in Ba-145 - art. no. 051304

High spin states in neutron-rich odd-Z Ba-143,Ba-145 nuclei have been inves tigated from the study of prompt gamma rays in the spontaneous fission of C f-252 by using gamma-gamma- and gamma-gamma-gamma- coincidence techniques. Alternating parity bands are identified for the first time in Ba-145 and ex tended in Ba-143. A new side band, with equal, constant dynamic, and kineti c moments of inertia equal to the rigid body value, as found in superdeform ed bands, is discovered in Ba-145. Enhanced E1 transitions between the nega tive- and positive-parity bands in these nuclei give evidence for strong oc tupole deformation in Ba-143 and in Ba-145. These collective bands show com petition and coexistence between symmetric and asymmetric shapes in Ba-145. Evidence is found for crossing M1 and E1 transitions between the s = +i an d s= -i doublers in Ba-143. [S0556-2813(99)50810-8].