Different manifestations of triaxial shapes of the positive and negative parity bands in Os187

The excited states of $^{187}\mathrm{Os}$ have been studied via $^{186}\mathrm{W}(^{4}\mathrm{He},3n)^{187}\mathrm{Os}$ reaction at a beam energy of 36 MeV. The $\ensuremath{\gamma}$ rays were detected using the Indian National Gamma Array at the Variable Energy Cyclotron Centre having seven Compton-suppressed clover high-purity germanium (HPGe) detectors and one low-energy photon spectrometer (LEPS) detector with a digital data acquisition system. The level scheme of $^{187}\mathrm{Os}$ has been extended substantially up to $\ensuremath{\approx}$3.86 MeV of excitation energy and $37/2\phantom{\rule{0.16em}{0ex}}\ensuremath{\hbar}$ of spin with the placement of more than 90 new $\ensuremath{\gamma}$ rays. All known bands have been extended and new band structures have been identified. The results show evidence of triaxial shapes for different configurations of $^{187}\mathrm{Os}$ and different manifestations of nonaxial shape have been observed in the same nucleus. A comparison of the observed band crossing frequency in $^{187}\mathrm{Os}$ with neighboring nuclei gives evidence of a deformed shell gap at $N=110$. The experimental results are well explained using total Routhian surface calculations.