The lifetime measurements are done for different quasiparticle bands in neutron-deficient ${}^{187}\mathrm{Tl}$ nucleus through the recoil distance Doppler shift technique. A sudden change in the transition quadrupole moment is observed for both positive and negative parity prolate bands as one moves from lower spins to higher spins, indicating a major shape transitions in this nucleus. The prolate-oblate shape coexistence picture of this nucleus is discussed in the light of the extracted transition quadrupole moments. For the negative parity $\pi h_{9/2}$ band the transition quadrupole moment for the low K (3/2) prolate sequence is found to be higher than that of the high K (9/2) oblate sequence. The total Routhian surface calculations are done within the framework of the cranked Hartree-Fock-Bogoliubov model to analyze the shape coexistence picture theoretically. The theoretical predictions are found to be in close agreement with the experimental observations. The existence of a superdeformed band is also predicted for the nucleus.

• Received 25 March 2004

DOI:https://doi.org/10.1103/PhysRevC.71.054324