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Nuclear Structure and Exotic Decays; Doubly-Magic 56Ni and Semi-Magic 58Ni

Johansson, Emma LU (2009)
Abstract
The nuclear structure of two nuclei, 56Ni and 58Ni, has been studied using fusion-evaporation

reaction experiments. The experiments were performed at the Lawrence

Berkeley and Argonne National Laboratories in the U.S.A.



The number of known spherical and deformed states in 56Ni has been

significantly extended. One case of prompt proton emission from a

well-deformed excited state into the ground state of 55Co was established. The spherical excited states were interpreted within the

spherical shell model, revealing a good agreement between theory and

experiment, with one notable exception for the yrast and yrare 8+ states. The

deformed states were interpreted... (More)
The nuclear structure of two nuclei, 56Ni and 58Ni, has been studied using fusion-evaporation

reaction experiments. The experiments were performed at the Lawrence

Berkeley and Argonne National Laboratories in the U.S.A.



The number of known spherical and deformed states in 56Ni has been

significantly extended. One case of prompt proton emission from a

well-deformed excited state into the ground state of 55Co was established. The spherical excited states were interpreted within the

spherical shell model, revealing a good agreement between theory and

experiment, with one notable exception for the yrast and yrare 8+ states. The

deformed states were interpreted using Cranked Nilsson-Strutinsky

calculations, again with very accurate results.



A similar investigation was performed for 58Ni, resulting in one of the

most extensive level schemes known for nuclei. High-spin states including

several rotational bands were found, and a significant number of

spherical and normally deformed states were also discovered. The rotational

bands were interpreted through Cranked Nilsson-Strutinsky calculations,

which allowed the configurations of the bands to be determined. The

normally deformed states of 58Ni were investigated with spherical

shell-model calculations, using two different interactions. The

results are in general satisfactory. The results indicate, however,

that further improvements of the theoretical calculations demands an

increase of the number of

subshells, allowed in the effective interactions.

A total of 12 prompt proton decays and two prompt alpha decays were

discovered in 58Ni. This is the

highest number of known particle decays of this type for any nucleus,

to date. New aspects of the proton decays have been observed, for

instance, two cases of in-band decays and two levels which decay with

competing proton, alpha, and gamma branches. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Bruce, Alison, University of Brighton, Brighton, U.K.
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Doubly magic, semi magic, 56Ni, 58Ni, high-spin states, fusion-evaporation reactions, cranked Nilsson-Strutinsky calculations, shell-model calculations, prompt proton decay, prompt alpha decay
pages
117 pages
defense location
Sal B, Fysiska instutionen
defense date
2009-01-23 13:15
ISBN
978-91-628-7679-1
language
English
LU publication?
yes
id
bc06a528-ff1b-44fd-8ac1-1155e500f4c8 (old id 1275218)
date added to LUP
2009-01-14 10:17:16
date last changed
2016-09-19 08:45:16
@phdthesis{bc06a528-ff1b-44fd-8ac1-1155e500f4c8,
  abstract     = {The nuclear structure of two nuclei, 56Ni and 58Ni, has been studied using fusion-evaporation<br/><br>
reaction experiments. The experiments were performed at the Lawrence<br/><br>
Berkeley and Argonne National Laboratories in the U.S.A.<br/><br>
<br/><br>
The number of known spherical and deformed states in 56Ni has been<br/><br>
significantly extended. One case of prompt proton emission from a<br/><br>
well-deformed excited state into the ground state of 55Co was established. The spherical excited states were interpreted within the <br/><br>
spherical shell model, revealing a good agreement between theory and<br/><br>
experiment, with one notable exception for the yrast and yrare 8+ states. The<br/><br>
deformed states were interpreted using Cranked Nilsson-Strutinsky<br/><br>
calculations, again with very accurate results.<br/><br>
<br/><br>
A similar investigation was performed for 58Ni, resulting in one of the<br/><br>
most extensive level schemes known for nuclei. High-spin states including<br/><br>
several rotational bands were found, and a significant number of<br/><br>
spherical and normally deformed states were also discovered. The rotational<br/><br>
bands were interpreted through Cranked Nilsson-Strutinsky calculations,<br/><br>
which allowed the configurations of the bands to be determined. The<br/><br>
normally deformed states of 58Ni were investigated with spherical<br/><br>
shell-model calculations, using two different interactions. The<br/><br>
results are in general satisfactory. The results indicate, however,<br/><br>
that further improvements of the theoretical calculations demands an<br/><br>
increase of the number of<br/><br>
subshells, allowed in the effective interactions. <br/><br>
A total of 12 prompt proton decays and two prompt alpha decays were<br/><br>
discovered in 58Ni. This is the<br/><br>
highest number of known particle decays of this type for any nucleus,<br/><br>
to date. New aspects of the proton decays have been observed, for<br/><br>
instance, two cases of in-band decays and two levels which decay with<br/><br>
competing proton, alpha, and gamma branches.},
  author       = {Johansson, Emma},
  isbn         = {978-91-628-7679-1},
  keyword      = {Doubly magic,semi magic,56Ni,58Ni,high-spin states,fusion-evaporation
reactions,cranked Nilsson-Strutinsky calculations,shell-model
calculations,prompt proton decay,prompt alpha decay},
  language     = {eng},
  pages        = {117},
  school       = {Lund University},
  title        = {Nuclear Structure and Exotic Decays; Doubly-Magic 56Ni and Semi-Magic 58Ni},
  year         = {2009},
}