Parities and multipolarities of gamma rays in neutron-rich odd-mass Ba nuclei

The nuclei Ba-143,Ba-145,Ba-147 produced in the spontaneous fission of Cm-248 have been studied using the EUROGAM phase II array. The parities and multipolarities of gamma rays in these nuclei have been assigned from triple angular correlation, directional linear-polarisation correlation and internal conversion coefficient measurements. These data confirm an alternating-parity sequence connected by strong electric dipole transitions in Ba-143. They also reveal a more weakly populated, complementary alternating-parity sequence. The two sequences together exhibit some characteristics of parity-doubler bands. Interpreting the El strengths in terms of a rotating intrinsic dipole moment gives a moment similar in size to that observed in Ba-142 and Ba-144. No well-developed similar structure is seen in Ba-145, although El transitions are observed, from which a value of the dipole moment is obtained. This value is smaller than the moment observed in Ba-143. No features appropriate to strong octupole correlations were observed in Ba-147.