Relative spins and excitation energies of superdeformed bands inHg190: Further evidence for octupole vibration

An experiment using the Eurogam phase II \ensuremath{\gamma}-ray spectrometer confirms the existence of an excited superdeformed (SD) band in $^{190}\mathrm{Hg}$ and its very unusual decay into the lowest SD band over 3--4 transitions. The energies of the transitions linking the two SD bands have been firmly established, and their angular distributions are consistent with a dipole character. Comparisons with calculations using random-phase approximation indicate that the excited SD band can be interpreted as an octupole-vibrational structure.