Parr, Edward
Spectroscopy of excited states in 252No.
Doctor of Philosophy thesis, University of Liverpool.
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Abstract
A spectroscopic study of excited states in $^{252}$No was carried out to gain experimental evidence of the energies, orderings and assignments for the single particle levels in the region around the deformed shell gaps at N = 152 and Z = 100. Some of these energy levels are of particular interest as they lie close to the Fermi surface in the spherical region around the predicted next magic numbers. The $^{252}$No nuclei were produced at the accelerator laboratory in Jyv\"{a}skyl\"{a}, Finland, using the fusion evaporation reaction $^{206}$Pb($^{48}$Ca,2n)$^{252}$No and separated with the RITU gas filled separator. The JUROGAM and GREAT detector arrays were used for in-beam and focal plane spectroscopy respectively, allowing the recoils to be identified using recoil-decay tagging techniques. The previously identified $K$$^\pi$ = 8$^-$ $K$ isomer was investigated, with in-beam $\gamma$-ray spectra of rotational band transitions above this state being observed for the first time and the level scheme up to $I$$^\pi$ = 19$^-$ (and up to 22$^-$ tentatively) being found. As the spectra produced were of low statistics, new approaches were required in their analysis to assign a single particle structural configuration to the excited state. Two methods are described which act to utilise the low statistics fully, the results of which provide strong indications that the 8$^-$\{$\frac{7}{2}$$^+$[624]$_{\nu}$$\otimes$$\frac{9}{2}$$^-$[734]$_{\nu}$\} configuration is responsible for the isomer. These results are also compared with other excited states in nuclei around the deformed shell gaps to build up a picture of regional systematics. Their bearing on the predictions for the next spherical shell closures is also discussed.
| Item Type: | Thesis (Doctor of Philosophy) |
|---|---|
| Additional Information: | Date: 2011 (completed) |
| Uncontrolled Keywords: | superheavy nuclei, isomeric states |
| Subjects: | ?? QC ?? |
| Divisions: | Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 17 Jan 2013 10:17 |
| Last Modified: | 16 Dec 2022 04:37 |
| DOI: | 10.17638/00007813 |
| Supervisors: |
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| URI: | https://livrepository.liverpool.ac.uk/id/eprint/7813 |
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