Nuclear structure near N =108 deformed shell gap: case of ¹⁸⁷Os

Osmium nuclei lie between the axially deformed prolate rare earth and spherical Pb nuclei. Many of the even-even Os isotopes are known to be γ-soft and odd-A Os isotopes show rotational bands based on different multi-quasiparticle configurations. The study of the dependence of different properties of these bands, e.g. the signature splitting, band crossing frequency, gain in alignment, etc., as a function of neutron and/or proton Fermi level is an important aspect in nuclear structure physics. The neutron Fermi levels in light Os nuclei lie in the mid-upper part of the i_13/2 orbital, so their shapes tend to take appreciable prolate deformation. However, as the Fermi level moves up to the upper part of the i_13/2 orbital, the oblate deformations are expected for the heavier ones. But the experimental data for heavier odd A Os isotopes are very scarce. We have performed an experiment to study the high spin state of ¹⁸⁷Os and have extended its earlier established level scheme through the observation of several new bands and band crossings for the first time. The band built on 7/2^-(503) configuration and its band crossing phenomenon have been discussed here