Quadrupole and octupole collectivity in $^{143}$Ba

Author(s): Morse, C; MacChiavelli, AO; Crawford, HL; Zhu, S; Wu, CY; Wang, YY; Meng, J; Back, BB; Bucher, B; Campbell, CM; Carpenter, MP; Chen, J; Clark, RM; Cromaz, M; Fallon, P; Henderson, J; Janssens, RVF; Jones, MD; Khoo, TL; Kondev, FG; Lauritsen, T; Lee, IY; Li, J; Potterveld, D; Santamaria, C; Savard, G; Seweryniak, D; Stolze, S; Weisshaar, D | Abstract: The neutron-rich barium nuclei have been the subject of intense interest due to the enhanced octupole correlations they are predicted to exhibit. The observation of enhanced octupole collectivity in Ba144,146 as measured in sub-barrier Coulomb excitation, consistent with static octupole deformation, has further heightened this interest. In the present work, these studies are extended to the neighboring odd-mass Ba143 to investigate the interplay between single-particle and collective octupole degrees of freedom. A new measurement of the first 92 - state lifetime is also presented. Reflection-Asymmetric Triaxial Particle Rotor Model calculations indicate that the negative-parity bands in Ba143 can be understood as a decoupled structure of νh9/2 parentage, while the positive-parity bands are built on a decoupled octupole phonon. No evidence for E3 excitation is observed in this work, but an upper limit is placed on the E3 matrix element to the lowest octupole band.