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The level scheme in highly deformed 131Eu has been established for the first time, providing crucial constraints on theoretical models of deformed proton emitters.

One of the fundamental goals in nuclear physics is to determine the limits on the number of neutrons and protons that can be bound within an atomic nucleus. Drip lines represent the limit of nuclei beyond which the nucleus becomes unbound to direct nucleon emission. In nuclei with an odd number of protons, proton emission determines whether the nucleus will live long enough to be identified and studied. In heavier elements, the Coulomb barrier slows the process enough that some proton-emitting nuclei are able to be studied with current experimental techniques.

The best known cases of deformed proton emitters are located in the 130≤A≤140 region. The focus of this thesis is 131Eu which has a deformation among the largest in this mass region, with a prolate (rugby ball) shape. To understand proton emission in such deformed nuclei requires both the proton emission data and information regarding the structure of excited states. Theoretical models make predictions, however the experimental measurements carried out in this thesis work to deduce the deformation of the 131Eu nucleus are crucial to refine these models.

The first identification of gamma rays in 131Eu was made utilising the Gammasphere spectrometer array and FMA at Argonne National Lab. The work carried out in this thesis was conducted with the MARA recoil separator and the JUROGAM 3 spectrometer. Tann was heavily involved in the construction of the movable germanium detector system, JUROGAM 3, which is used to detect gamma radiation. The data from this study, taken in 2019, was highly fruitful and through gamma-ray correlations it was possible to build rotational band(s) in the nucleus for the first time. Tann was the Liaison for this experiment and analysed the data, which will form a future publication as part of a larger international research collaboration.

In 2015, Tann did an internship at CERN on the ALPHA experiment. She graduated with a Master’s degree in Physics (MPhys) from the University of Liverpool in 2017 and began a Dual Doctorate between the University of Liverpool and the Ģ��ֱ��. Tann worked as a Doctoral Researcher at the Ģ��ֱ��'s accelerator laboratory between 2018-2020, and graduated from the University of Liverpool as a Doctor of Philosophy in 2022. Tann is now one of the Directors of the humanitarian non-profit organisation Casus Pax, procuring and delivering medical aid to civilians on the frontlines in Ukraine.

Opponent Dr. Martin Venhart (Slovak Academy of Sciences) and custos Senior Researcher Juha Uusitalo (Ģ��ֱ��). The language of the dissertation is English.

The dissertation has been published in an online publication series and is available in the JYX publication archive: