Date of Award

10-17-2024

Author's School

Graduate School of Arts and Sciences

Author's Department

Physics

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

The collection of proton decays observed via invariant-mass spectroscopy in this work have been applied to an array of topics in nuclear physics including the continuum effects on near-threshold resonances, the branching ratio for a quasi-bound system, and evidence for the evolution of shell structure. In the first experiment, the 6He(d,n)7Li* reaction was employed in an attempt to populate a resonance predicted by an ab initio calculation. No evidence of this resonance was found leading to a discussion on how the model needs to be improved in order to treat nuclear states above multiple thresholds. In a separate experiment, the p/gamma branching ratio for the first 2+ state of 36Ca was studied and measured to be Bp = 0.087(8). This branching ratio enabled the measurement of a B(E2, 0+_1 → 2+_1) strength of 36Ca [B(E2↑) = 131(20) e^2fm^4]. The B(E2) and branching-ratio values can be reproduced in the shell-model with the ZMB2 interaction, an interaction that predicts the Z=20 sd-shell closure is incomplete with large proton pf-shell occupancies in the ground state. This experiment also resulted in a set of reactions populating proton-rich nuclei including 35Ca and the first observations of 37Sc, 38Sc, and 34K. Proton decays for these nuclei were reconstructed, yielding three new ground-state masses and information on their low-lying structures. The newly-measured mass excesses are: ΔM(37Sc) = 3500(410) keV, ΔM(38Sc) = -4656(14) keV, and ΔM(34K) = -1487(17) keV. These masses enable us to look at trends in separation energies, which help elucidate how nuclear structure evolves, showing a fading of the Z=20 shell gap for N≤18 and indications of a N=16 subshell gap.

Language

English (en)

Chair and Committee

Lee Sobotka

Committee Members

Robert Charity, Manel Errando; Saori Pastore; Willem Dickhoff

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