Isospin symmetry investigated through one- and two-nucleon knockout reactions

Lead Research Organisation: University of York
Department Name: Physics

Abstract

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Publications

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Boso A (2019) Isospin dependence of electromagnetic transition strengths among an isobaric triplet in Physics Letters B

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Fernández A (2021) Mirror energy differences above the 0f7/2 shell: First ?-ray spectroscopy of the T = -2 nucleus 56Zn in Physics Letters B

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Yajzey R (2021) Spectroscopy of the T = 2 mirror nuclei 48Fe/48Ti using mirrored knockout reactions in Physics Letters B

Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/R505213/1 30/09/2017 29/09/2021
2107063 Studentship ST/R505213/1 30/09/2018 30/03/2022 Sivahami Uthayakumaar
ST/S50581X/1 30/09/2018 29/09/2022
2107063 Studentship ST/S50581X/1 30/09/2018 30/03/2022 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