Backbending in the pear-shaped 223(90)Th nucleus: Evidence of a high-spin octupole to quadrupole shape transition in the actinides
Maquart, G., Augey, L., Chaix, L., Companis, I., Ducoin, C., Dudouet, J., . . . Uusitalo, J. (2017). Backbending in the pear-shaped 223(90)Th nucleus: Evidence of a high-spin octupole to quadrupole shape transition in the actinides. Physical Review C, 95 (3), 034304. doi:10.1103/PhysRevC.95.034304
Published inPhysical Review C
Gall, B. |
© 2017 American Physical Society. Published in this repository with the kind permission of the publisher.
Relatively neutron-rich thorium isotopes lie at the heart of a nuclear region of nuclei exhibiting octupole correlation effects. The detailed level structure of 223Th has been investigated in measurements of γ radiation following the fusion-evaporation channel of the 208Pb(18O ,3n) 223Th reaction at 85 MeV beam energy. The level structure has been extended up to spin 49/2, and 33 new γ rays have been added using triple-γ coincidence data. The spins and parities of the newly observed states have been confirmed by angular distribution ratios. In addition to the two known yrast bands based on a K = 5/2 configuration, a non-yrast band has been established up to spin 35/2. We interpret this new structure as based on the same configuration as the yrast band in 221Th having dominant K = 1/2 contribution. At the highest spin a backbending occurs around a rotational frequency of ¯hω = 0.23 MeV, very close to the one predicted in 222Th, where a sharp transition to a reflection-symmetric shape is expected. ...