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The role of seniority-zero states in nuclear level densities

Åberg, Sven LU ; Carlsson, Gillis LU ; Dossing, Th. and Moller, P. (2015) In Nuclear Physics, Section A 941. p.97-120
Abstract
At low excitation energies seniority-zero states dominate the level density of K = 0 bands in deformed even even nuclei, while they play no role at higher excitation energies. We describe the level densities in a Fermi-gas model as well as in a combinatorial level-density model and compare to detailed experimental data for some rare-earth nuclei. An explanation is provided for recent observations of an odd even staggering in the spin-distribution function as an effect of r-symmetry of wave functions for deformed nuclei. The structure of 0(+) states in deformed nuclei is discussed in the model and compared to data, stressing the role of the seniority quantum number. The Fermi-gas model is utilized to obtain an overview of the odd even... (More)
At low excitation energies seniority-zero states dominate the level density of K = 0 bands in deformed even even nuclei, while they play no role at higher excitation energies. We describe the level densities in a Fermi-gas model as well as in a combinatorial level-density model and compare to detailed experimental data for some rare-earth nuclei. An explanation is provided for recent observations of an odd even staggering in the spin-distribution function as an effect of r-symmetry of wave functions for deformed nuclei. The structure of 0(+) states in deformed nuclei is discussed in the model and compared to data, stressing the role of the seniority quantum number. The Fermi-gas model is utilized to obtain an overview of the odd even staggering phenomenon in other mass regions. Odd even staggering in spherical nuclei, appearing in open-shell nuclei, is briefly discussed as caused by fermion exchange symmetry. (C) 2015 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Level-density, Seniority-zero states, Spin-distribution, 0(+)-states
in
Nuclear Physics, Section A
volume
941
pages
97 - 120
publisher
Elsevier
external identifiers
  • wos:000360515100008
  • scopus:84935010919
ISSN
0375-9474
DOI
10.1016/j.nuclphysa.2015.05.009
language
English
LU publication?
yes
id
2479b69f-f2f4-4682-81b5-5d45de85912f (old id 8077589)
date added to LUP
2015-10-26 14:13:52
date last changed
2017-04-02 03:41:36
@article{2479b69f-f2f4-4682-81b5-5d45de85912f,
  abstract     = {At low excitation energies seniority-zero states dominate the level density of K = 0 bands in deformed even even nuclei, while they play no role at higher excitation energies. We describe the level densities in a Fermi-gas model as well as in a combinatorial level-density model and compare to detailed experimental data for some rare-earth nuclei. An explanation is provided for recent observations of an odd even staggering in the spin-distribution function as an effect of r-symmetry of wave functions for deformed nuclei. The structure of 0(+) states in deformed nuclei is discussed in the model and compared to data, stressing the role of the seniority quantum number. The Fermi-gas model is utilized to obtain an overview of the odd even staggering phenomenon in other mass regions. Odd even staggering in spherical nuclei, appearing in open-shell nuclei, is briefly discussed as caused by fermion exchange symmetry. (C) 2015 Elsevier B.V. All rights reserved.},
  author       = {Åberg, Sven and Carlsson, Gillis and Dossing, Th. and Moller, P.},
  issn         = {0375-9474},
  keyword      = {Level-density,Seniority-zero states,Spin-distribution,0(+)-states},
  language     = {eng},
  pages        = {97--120},
  publisher    = {Elsevier},
  series       = {Nuclear Physics, Section A},
  title        = {The role of seniority-zero states in nuclear level densities},
  url          = {http://dx.doi.org/10.1016/j.nuclphysa.2015.05.009},
  volume       = {941},
  year         = {2015},
}