Behavior of the Excited Deformed Band and Search for Shape Isomerism inHg184

Abstract

The new isotope ${}_{}{}^{184}{}_{}{}^{}\mathrm{Tl}$ has been identified with $T_{\frac{1}{2}}=11\mathrm{}\pm 1$ sec and the levels in ${}_{}{}^{184}{}_{}{}^{}\mathrm{Hg}$ investigated from its decay. The $0^{+}$ band head of a deformed band was found to drop to 375 keV in agreement with theoretical predictions. The mean life of the 375-keV $0^{+}$ level was measured to be 0.9 ± 0.3 nsec which is a factor of 10 faster than theoretically predicted for a shape-isomeric $E2\mathrm{}$ transition.