Exotic Nuclear Deformation and the Evolution of Nuclear Structure with Angular Momentum and Excitation Energy in ¹⁵⁷Ho, ¹⁶⁶Er, and ¹⁶⁹,¹⁷⁰Yb
Nuclei in the light rare-earth, for values of N ≥ 90, are textbook examples of the evolution of nuclear structure with respect to excitation energy and angular momentum in deformed nuclei. In the high-spin region (J ≥ 10ħ), effects such as backbends and shape changes occur, ending with t...
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| Format: | Others |
| Language: | English English |
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Florida State University
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| Online Access: | http://purl.flvc.org/fsu/fd/2018_Fall_Baron_fsu_0071E_14887 |
| Summary: | Nuclei in the light rare-earth, for values of N ≥ 90, are textbook examples of the evolution of nuclear structure with respect to
excitation energy and angular momentum in deformed nuclei. In the high-spin region (J ≥ 10ħ), effects such as backbends and shape changes occur,
ending with termination of the lower energy collective structures. First backbends occur before 20ħ Findings also reflect a spectacular return
to collectivity in the "ultra-high spin" region (J ≥ 50ħ). Thanks to recent developments in both detectors and accelerators, gamma-ray
spectroscopy has been able to probe the upper ends of the high-spin region, and begin probing into the ultra-high spin regime. Data from two
experiments form the basis of this work. One study was an ultra-high-spin analysis of the Z=67, N=90 ¹⁵⁷Ho nucleus at Argonne National
Laboratory with Gammasphere. The findings were that remarkable correlations were observed to the neighboring isotone, ¹⁵⁸Er, in which
termination states and ultra-high spin structures had been previously observed. A high-spin investigation of Ytterbium (Yb) and Erbium (Er)
isotopes was performed at FSU. This study used an intense radioactive ¹⁴C beam, available at FSU, in order to study these heavy, neutron-rich
nuclei in regions of angular momentum and excitation energy not attainable with stable beams. The reactions of ¹⁷⁰Er(¹⁴C,5n/4n/α4n) generated
new information in ¹⁶⁹Yb, ¹⁷⁰Yb, and ¹⁶⁶Er, respectively. Due to the recently upgraded digital FSU Gamma-Ray Array, aided by JBSMILE, triple
ᵧ-ray coincidences were able to be viewed in these nuclei for the first time at FSU. The result was the investigation of rotational alignments
in both the yrast and non-yrast multi-quasiparticle bands in these nuclei. === A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree
of Doctor of Philosophy. === Fall Semester 2018. === November 19, 2018. === Includes bibliographical references. === Mark A. Riley, Professor Directing Dissertation; Oliver Steinbock, University Representative; Samuel L.
Tabor, Committee Member; Alexander Volya, Committee Member; Laura Reina, Committee Member. |
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