Isomer decay spectroscopy ofneutron-rich nuclei around A ∼210

ABSTRACT: This thesis presents the results of an experiment performed at the GSI Laboratory, Darmstadt, Germany. The experiment aimed at studying the nuclear structure of neutron-rich nuclei around the 208Pb double-shell closure nucleus. Isotopes were produced via projectile fragmentation, separated and selected through the FRS spectrometer and studied via the RISING setup in its "stopped beam" configuration. The experimental technique employed is the isomer-decay γ-ray spectroscopy. Ten different isotopes, ranging from Au to Po, have been studied: their partial level schemes have been reconstructed from γ- γ coincidences, while the lifetime of their isomeric states has been extracted from the time distribution of the de-excitation γ rays. A new transition of 533 keV in 212Po has been found, which has no counterpart in literature, and it is assigned to the long-sought 21- → 18+ E3. A strength between an upper value of 18 ± 4 W.u. and a lower bound of 12 ± 4 W.u. is deduced for this transition. The assignment is deduced from its isomeric ratio and systematics in the region. Results are compared to shell-model calculations.