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Title: Investigation of isospin symmetry breaking in the f7/2 region, studied through one-nucleon knockout and lifetime measurements
Author: Milne, Scott Alexander
ISNI:       0000 0004 6062 486X
Awarding Body: University of York
Current Institution: University of York
Date of Award: 2016
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In this thesis, the results of two experiments are presented. The first experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU), USA, while the second experiment was performed at the Gesellschaft für SchwerIonenforschung (GSI) facility near Darmstadt, Germany. For the experiment performed at MSU, γ-ray spectroscopy has been performed for both the mirror Tz=±3/2 pair 53Ni and 53Mn, produced via mirrored one-nucleon knockout, and the Tz=-1 nuclide 52Co, produced via one-neutron knockout. Several new transitions have been identified in both 53Ni and 52Co, from which new level schemes have been constructed. The presence of a high-spin isomeric state (Jπ=19/2-) in the 53Co beam facilitated the study of high-spin states up to and including the 11+ band termination state in 52Co, where this work also represents the first use of this new technique (isomer knockout) to study high-spin states in exotic nuclei. Relative cross sections for knockout have been analysed and compared with reaction model calculations, where a high level of agreement is observed, especially for states in 52Co. Mirror Energy Differences (MED) between Isobaric Analogue States (IAS) have been measured, compared to large scale shell-model calculations and interpreted in terms of INC effects for both the Tz=±1, A=52 and Tz=±3/2, A=53 mirror pairs. The analysis presented here demonstrates the importance of including a full set of J-dependent INC terms to explain the experimental observations. Finally, lifetimes for the long-lived Jπ=5/2- analogue states in both 53Mn and 53Ni have been extracted through lineshape analysis, giving half-lives of T1/2=120(14)ps and T1/2=198(12)ps, respectively. In the experiment performed at GSI, Coulex and lifetime measurements (using a novel 'stretched gold target' technique) were performed for the analogue 2+(T=1) → 0+(T=1) transition across the A=46, T=1 isobaric triplet 46Cr(Tz=-1), 46V(Tz=0) and 46Ti(Tz=+1). Preliminary Coulex cross sections have been obtained and a 'proof-of-principle' test has been performed for the new lifetime method.
Supervisor: Bentley, Michael Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available