ALIGNMENT EFFECTS IN ODD-MASS CS ISOTOPES - SPECTROSCOPY OF CS-125

Several rotational bands have been populated in the Z = 55 nucleus 125Cs using the fusion evaporation reaction Pd-110(F-19,4n), at a beam energy of 74 MeV. The resultant gamma rays were detected using standard gamma-ray spectroscopic techniques with an array of six Compton-suppressed Ge detectors and a fourteen-element bismuth-germanate ball. The low-lying yrast structure is found to be dominated by the unique parity pi-h11/2 orbital, manifest as a decoupled band with a large signature splitting. A crossing occurs in this band at HBAR-omega-c = 0.42 MeV, which is interpreted as [nu-h11/2]2 pair alignment. In addition, a strongly coupled negative-parity structure with large B(M1)/B(E2) ratios is observed feeding both signatures of the pi-h11/2 band. Bands built on the normal-parity pi-g7/2 and pi-g9/2(-1) orbitals have also been confirmed and extended. These structures are compared to cranked-shell-model calculations and the systematics of the region.