Isospin symmetry investigated through one- and two-nucleon knockout reactions
Lead Research Organisation:
University of York
Department Name: Physics
Abstract
The project will investigate isospin symmetry through spectroscopy of proton-rich nuclei. The project will entail analysis of data from one- and two-nucleon knockout reactions from relativistic fragmentation beams at the NSCL Facility in Michigan USA and the RIKEN Facility in Japan. we will examine mirrored knockout reactions in the f7/2 to extract mirrored (analogue) spectroscopic strengths to examine the symmetry of the underlying analogue states. We will apply state-of-the-art theoretical models to analyse the data exploiting large scale shell-model calculations to predict both energy differences between the analogue states and the spectroscopic strength for each direct reaction. A number of nuclei near the drip line will be studied for the first time in the analysis - including 47Mn, 46Mn, 45Cr and 56Zn.
Organisations
People |
ORCID iD |
| Michael Bentley (Primary Supervisor) | |
| Sivahami Uthayakumaar (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| ST/R505213/1 | 01/10/2017 | 30/09/2021 | |||
| 2107063 | Studentship | ST/R505213/1 | 01/10/2018 | 31/03/2022 | Sivahami Uthayakumaar |
| ST/S50581X/1 | 01/10/2018 | 30/09/2022 | |||
| 2107063 | Studentship | ST/S50581X/1 | 01/10/2018 | 31/03/2022 | Sivahami Uthayakumaar |
| Description | The level-scheme of the proton-rich 47Mn and 45Cr nuclei have been constructed for the first time which details the decay of gamma-rays from higher energy states to low-lying states. The assignment of where these gamma-rays decay to has been compared to their respective mirror nuclei, 47Ti and 45Sc, found by interchanging the number of protons and neutrons by utilising a fundamental concept of isospin symmetry. Due to mirror symmetry arguments, it is assumed that the level schemes of both 47Mn/47Ti and 45Cr/45Sc mirror nuclei should be the same. However, in reality, this is not the case due to isospin breaking effects. These effects have been studied by utilising state-of-the-art shell-model calculations to explore mirror energy differences (MEDs) which have been compared to a recently developed density-functional theory (DFT) approach. A key measurement that has been made is the knockout cross-sections of the 47Mn/47Ti mirror pair for which the difference between the cross-sections were found to differ by a factor of 11. A reason for this large difference is due to the binding energy effects, where the large binding energy of 47Ti compared to the low proton separation energy in 47Mn, are shown to exhibit asymmetric behaviour. In addition, all fp- and deep-lying sd-shell removal paths are likely to contribute to the population of bound states in 47Ti which in turn leads to a large cross-section. The lifetime of the first-excited state in the 47Mn/47Ti mirror pair has also been measured to extract information about the transition strength, especially for the 47Mn case. The results have been compared to the shell-model calculations and are currently being understood. |
| Exploitation Route | This work will extend to nuclear astrophysics to develop our understanding of nuclear astronomical phenomenon such as the rapid-proton (rp) process and how these exotic proton-rich nuclei are produced during this process. |
| Sectors | Education |