Transition Strength Ratios in the Tetrahedral Candidate $^{156}$Dy

A new symmetry has been recently proposed where nuclei may stabilize in a tetrahedral (pyramid) shape. One of the consequences of this symmetry is that the transition strength, $B(E2)$, of the inband transitions should approach zero in the ideal case. Thus, one signal of this exotic shape would be a rotational band where the inband $E2$ transitions are extremely weak or nonexistent. Such bands exist in many of the lowest negative-parity bands in the $N\approx 90$ nuclei, which is also a predicted ``magic" region for tetrahedral symmetry. A Gammasphere experiment was performed to measure the $B(E2)/B(E1)$ ratios of such a negative-parity band in $^{156}$Dy. The results (which are consistent with the theory) will be presented, as well as a discussion of the proposed follow-up experiment to directly measure the $B(E2)$ rates.