The role of seniority-zero states in nuclear level densities

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title = "The role of seniority-zero states in nuclear level densities",
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.",
keywords = "Level-density, Seniority-zero states, Spin-distribution, 0(+)-states",
author = "Sven {\AA}berg and Gillis Carlsson and Th. Dossing and P. Moller",
note = "The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Mathematical Physics (Faculty of Technology) (011040002)",
year = "2015",
doi = "10.1016/j.nuclphysa.2015.05.009",
language = "English",
volume = "941",
pages = "97--120",
journal = "Nuclear Physics A",
issn = "0375-9474",
publisher = "Elsevier",