Detailed spectroscopy of 195Bi

An experiment focused on the study of shape coexistence and new high-spin structures in 195Bi has been performed. The nucleus is in a transitional region of the bismuth isotope chain. A large number of new states have been found, resulting in a significant extension of the previously known level scheme. Several new collective structures have been identified. A strongly coupled rotational band built upon the 13/2+ isomeric state was extended up to Iπ=(49/2+) and an energy of 5706 keV. The Iπ=31/2+ member of the πi13/2 band was also found to feed a new long-lived isomeric state with an excitation energy of 2616 keV and a spin and parity of Iπ=29/2+. The half-life of the 29/2+ isomeric state was determined to be 1.49(1)μs. It decays via the emission of 457-keV E2 and 236-keV E1 transitions, respectively. A low-energy 46-keV E2 transition has been identified to depopulate the (29/2−) isomeric state, with a measured half-life of T1/2=614(5)ns. This transition allows the excitation energy of the isomeric state to be determined as 2381 keV. The feeding patterns of both 29/2+ and (29/2−) isomeric states have also been described. This is the first time collective structures have also been observed up to high spins and excitation energies in the neutron-deficient 195Bi nucleus. Evidence for the manifestation of shape coexistence in 195Bi is also discussed.