Detailed spectroscopy of 195Bi

Abstract

An experiment focused on the study of shape coexistence and new high-spin structures in 195 Bi 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 I π = ( 49 / 2 + ) and an energy of 5706 keV. The I π = 31 / 2 + member of the π i 13 / 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 I π = 29 / 2 + . The half-life of the 29 / 2 + isomeric state was determined to be 1.49 ( 1 ) μ s . It decays via the emission of 457-keV E 2 and 236-keV E 1 transitions, respectively. A low-energy 46-keV E 2 transition has been identified to depopulate the ( 29 / 2 − ) isomeric state, with a measured half-life of T 1 / 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 195 Bi nucleus. Evidence for the manifestation of shape coexistence in 195 Bi is also discussed.