Spectroscopy of very neutron deficient Po isotopes utilizing the recoil-decay tagging method

Abstract

In this thesis an experimental setup, consisting of a gas-filled recoil separator RITU and varying germanium detector arrays has been commissioned at the accelerator laboratory of the University of Jyväskylä. The relevant analysis methods, including recoil gating and the recoil-decay tagging (RDT) method are discussed. The setup, combined with the ROT method has proven to be a very powerful tool in the study of heavy, very neutron-deficient nuclei. With this setup, prompt and delayed y rays from the neutron-deficient nuclei 192-195Po have been studied. The excited states in 192Po have been observed for the first time. New excited levels, including isomeric states in 192, 194Po and tentative unfavoured states in the odd-mass isotopes 193, 195Po, have been identified. The new data has been combined with the existing energy-level systematics. The new results have been used to test several nuclear models used in the description of the neutron-deficient Po isotopes. The data are in accordance with the scheme of the coexisting normal spherical and intruding oblate structures crossing each other in Po isotopes with N ≤114.