Different manifestations of triaxial shapes of the positive and negative parity bands in Os-187

The excited states of 187Os have been studied via 186W(4He, 3n) 187Os reaction at a beam energy of 36 MeV. The 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 187Os has been extended substantially up to approximate to 3.86 MeV of excitation energy and 37/2 h over bar of spin with the placement of more than 90 new 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 187Os and different manifestations of nonaxial shape have been observed in the same nucleus. A comparison of the observed band crossing frequency in 187Os with neighboring nuclei gives evidence of a deformed shell gap at N = 110. The experimental results are well explained using total Routhian surface calculations.