The role of seniority-zero states in nuclear level densities

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The role of seniority-zero states in nuclear level densities. / Åberg, Sven; Carlsson, Gillis; Dossing, Th.; Moller, P.

I: Nuclear Physics, Section A, Vol. 941, 2015, s. 97-120.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - The role of seniority-zero states in nuclear level densities

AU - Åberg, Sven

AU - Carlsson, Gillis

AU - Dossing, Th.

AU - Moller, P.

N1 - 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)

PY - 2015

Y1 - 2015

N2 - 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.

AB - 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.

KW - Level-density

KW - Seniority-zero states

KW - Spin-distribution

KW - 0(+)-states

U2 - 10.1016/j.nuclphysa.2015.05.009

DO - 10.1016/j.nuclphysa.2015.05.009

M3 - Article

VL - 941

SP - 97

EP - 120

JO - Nuclear Physics A

JF - Nuclear Physics A

SN - 0375-9474

ER -