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Statistical theory of deformation distributions in nuclear spectra

Apr 4, 2018

12 pages

Published in:

Phys.Rev.C 98 (2018) 3, 034317

Published: Sep 22, 2018

e-Print:

1804.01617 [nucl-th]

DOI:

10.1103/PhysRevC.98.034317

Report number:

INT-PUB-18-024

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Abstract: (APS)

The dependence of the nuclear level density on intrinsic deformation is an important input to dynamical nuclear processes such as fission. The auxiliary-field Monte Carlo (AFMC) method is a powerful method for computing state densities. However, the statistical distribution of intrinsic shapes is not readily accessible due to the formulation of the AFMC method in a spherical configuration-interaction shell-model approach. Instead, the theory of deformation has largely relied on a mean-field approximation which breaks rotational symmetry. We show here how the distributions of the intrinsic quadrupole deformation parameters can be calculated within the AFMC method and present results for a chain of even-mass samarium nuclei (Sm148, Sm150, Sm152, Sm154) which includes spherical, transitional, and strongly deformed isotopes. The method relies on a Landau-like expansion of the Helmholtz free energy in invariant polynomials of the quadrupole tensor. We find that an expansion to fourth order provides an excellent description of the AFMC results.

Note:

13 pages, 11 figures

Nuclear Structure

References(34)

Figures(11)

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