Multidimensionally-constrained relativistic mean- field study of spontaneous fission: Coupling between shape and pairing degrees of freedom

Scientific paper - Original scientific paper

• Author: Jie Zhao
• Author: Bing-nan Lu
• Author: Tamara Nikšić; MBZ: 234533
• Author: Dario Vretenar; MBZ: 9570
• Author: Shan-Gui Zhou
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

Background: Studies of fission dynamics, based on nuclear energy density functionals, have shown that the coupling between shape and pairing degrees of freedom has a pronounced effect on the nonperturbative collective inertia and, therefore, on dynamic (least-action) spontaneous fission paths and half-lives. Purpose: The aim is to analyze the effects of particle-number fluctuation degrees of freedom on symmetric and asymmetric spontaneous fission (SF) dynamics, and to compare the findings with the results of recent studies based on the self-consistent Hartree-Fock-Bogoliubov (HFB) method. Methods: Collective potentials and nonperturbative cranking collective inertia tensors are calculated using the multidimensionally- constrained relativistic-mean-field (MDC-RMF) model. Pairing correlations are treated in the BCS approximation using a separable pairing force of finite range. Pairing fluctuations are included as a collective variable using a constraint on particle-number dispersion. Fission paths are determined with the dynamic programming method by minimizing the action in multidimensional collective spaces. Results: The dynamics of spontaneous fission of Fm264 and Fm250 are explored. Fission paths, action integrals, and corresponding half-lives computed in the three-dimensional collective space of shape and pairing coordinates, using the relativistic functional DD-PC1 and a separable pairing force of finite range, are compared with results obtained without pairing fluctuations. Results for Fm264 are also discussed in relation with those recently obtained using the HFB model. Conclusions: The inclusion of pairing correlations in the space of collective coordinates favors axially symmetric shapes along the dynamic path of the fissioning system, amplifies pairing as the path traverses the fission barriers, significantly reduces the action integral, and shortens the corresponding SF half-life.

• Keywords (english): fission; nuclear energy density functional
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review C
• Numbering: vol. 93, no. 4, 044315
• p-ISSN: 2469-9985
• e-ISSN: 2469-9993
• DOI: https://doi.org/10.1103/PhysRevC.93.044315
• URN:NBN: urn:nbn:hr:217:221722
• Publication: 2016
• Project: Number: IP-2014-09-9159; Title (croatian): Struktura i dinamika egzotičnih femto-sustava; Acronym: STRUDEF; Leader: Nils Paar; Jurisdiction: Croatia; Funding stream: IP
• Document URL: https://journals.aps.org/prc/abstract/10.1103/PhysRevC.93.044315
• Type of resource: Text
• Access conditions: Open access
• Public note: © 2016 American Physical Society. Received 29 February 2016; published 15 April 2016.
• Created on: 2020-02-23 14:07:13