Investigation Of Negative-Parity States In Dy-156: Search For Evidence Of Tetrahedral Symmetry

An experiment populating low/medium-spin states in Dy-156 was performed to investigate the possibility of tetrahedral symmetry in this nucleus. In particular, focus was placed on the low-spin, negative-parity states since recent theoretical studies suggest that these may be good candidates for this high-rank symmetry. The states were produced in the Nd-148(C-12, 4n) reaction and the Gammasphere array was utilized to detect the emitted. rays. B(E2)/B(E1) ratios of transition probabilities from the low-spin, negative-parity bands were determined and used to interpret whether these structures are best associated with tetrahedral symmetry or, as previously assigned, to octupole vibrations. In addition, several other negative-parity structures were observed to higher spin and two new sequences were established.