Identification of new transitions and levels in Gd-163 from beta-decay studies

Background: Neutron-rich nuclei in the mass region around A = 160 have been and will continue to be of interest for the study of nuclear structure because of the rapid onset of deformation between 88 and 90 neutrons. The observation of detailed changes in nuclear structures within this mass region has provided and will continue to provide insight into the nuclear force. Purpose: Investigations of gamma rays emitted following Eu-163 beta-decay to Gd-163 have been performed for evaluation of the nuclear structure of Gd-163. Method: Data were collected at the LeRIBSS station of the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory with an array of four Clover HPGe detectors for gamma-rays and two plastic scintillators for beta detection. The gamma rays were identified as belonging to Gd-163 via mass selection and gamma-gamma-beta, x-ray-gamma, or gamma-gamma coincidences. Results: In total 107 new gamma -ray transitions were observed in Gd-163 from 53 newly identified levels. Conclusions: The structure of Gd-163 has been identified for the first time. This structure has been evaluated in comparison to projected shell model, and potential energy surface calculations with good agreement.