Departmental Oral Examination (Thesis Title: “Decay Spectroscopy of Neutron-Rich Cadmium Around the N = 82 Shell Closure")

Abstract:
The neutron-rich cadmium isotopes around the well-known magic numbers at Z=50 and N=82 are prime candidates to study the evolving shell structure observed in exotic nuclei. Additionally, the extra binding energy observed around the nearby doubly-magic Sn-132 has direct implications for in astrophysical models, leading to the second r-process abundance peak at A~130 and the corresponding waiting-point nuclei around N=82. The beta-decay of the N=82 isotope Cd-130 into In-130 was investigated in 2002, but the information for states of the lighter indium isotope In-128 is still limited.

Detailed beta-gamma-spectroscopy of Cd-128,131,132 was accomplished using the GRIFFIN facility at TRIUMF. In In-128, 32 new transitions and 11 new states have been observed in addition to the four previously observed excited states. The Cd-128 half-life has also been remeasured via the time distribution of the strongest gamma-rays in the decay scheme with a higher precision. For the decay of Cd-131,132, results are compared with the recent EURICA data. These new results are compared with recent shell model and IMSRG calculations, highlighting the necessity to re-investigate even "well-known" decay schemes for missing transitions.