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Title: Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory

Abstract

Background: The reactions with the neutron-rich 48Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104 118. The unambiguous identification of the new isotopes, however, still poses a problem because their -decay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between -decay and SF channels in SH nuclei is, therefore, of crucial importance for our ability to map the SH region and to assess its extent. Purpose: We perform self-consistent calculations of the competing decay modes of even-even SH isotopes with 108 Z 126 and 148 N 188. Methods: We use the state-of-the-art computational framework based on self-consistent symmetry-unrestricted nuclear density functional theory capable of describing the competition between nuclear attraction and electrostatic repulsion. We apply the SkM* Skyrme energy density functional. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (HFB) approach. This paper constitutes a systematic self-consistent study of spontaneous fission in the SH region, carried out at a full HFB level, that simultaneously takes into account both triaxiality and reflection asymmetry. Results: Breaking axial symmetry andmore » parity turns out to be crucial for a realistic estimate of collective action; it results in lowering SF lifetimes by more than 7 orders of magnitude in some cases. We predict two competing SF modes: reflection symmetric modes and reflection asymmetric modes. Conclusions: The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by 280Hs, 284Fl, and 118284Uuo that separates the regions of SH nuclei synthesized in cold-fusion and hot-fusion reactions. The region of long-lived SH nuclei is expected to be centered on 294Ds with a total half-life of 1.5 days. Our survey provides a solid benchmark for the future improvements of self-consistent SF calculations in the region of SH nuclei.« less

Authors:
 [1];  [1];  [2]
  1. UTK/ORNL/Inst. Physics, Maria Curie-Sklodowska University, Poland
  2. UTK/ORNL/University of Warsaw
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1092347
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 87; Journal Issue: 2; Journal ID: ISSN 0556--2813
Country of Publication:
United States
Language:
English

Citation Formats

Staszczak, A, Baran, A., and Nazarewicz, Witold. Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory. United States: N. p., 2013. Web. doi:10.1103/PhysRevC.87.024320.
Staszczak, A, Baran, A., & Nazarewicz, Witold. Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory. United States. https://doi.org/10.1103/PhysRevC.87.024320
Staszczak, A, Baran, A., and Nazarewicz, Witold. Tue . "Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory". United States. https://doi.org/10.1103/PhysRevC.87.024320.
@article{osti_1092347,
title = {Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory},
author = {Staszczak, A and Baran, A. and Nazarewicz, Witold},
abstractNote = {Background: The reactions with the neutron-rich 48Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104 118. The unambiguous identification of the new isotopes, however, still poses a problem because their -decay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between -decay and SF channels in SH nuclei is, therefore, of crucial importance for our ability to map the SH region and to assess its extent. Purpose: We perform self-consistent calculations of the competing decay modes of even-even SH isotopes with 108 Z 126 and 148 N 188. Methods: We use the state-of-the-art computational framework based on self-consistent symmetry-unrestricted nuclear density functional theory capable of describing the competition between nuclear attraction and electrostatic repulsion. We apply the SkM* Skyrme energy density functional. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (HFB) approach. This paper constitutes a systematic self-consistent study of spontaneous fission in the SH region, carried out at a full HFB level, that simultaneously takes into account both triaxiality and reflection asymmetry. Results: Breaking axial symmetry and parity turns out to be crucial for a realistic estimate of collective action; it results in lowering SF lifetimes by more than 7 orders of magnitude in some cases. We predict two competing SF modes: reflection symmetric modes and reflection asymmetric modes. Conclusions: The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by 280Hs, 284Fl, and 118284Uuo that separates the regions of SH nuclei synthesized in cold-fusion and hot-fusion reactions. The region of long-lived SH nuclei is expected to be centered on 294Ds with a total half-life of 1.5 days. Our survey provides a solid benchmark for the future improvements of self-consistent SF calculations in the region of SH nuclei.},
doi = {10.1103/PhysRevC.87.024320},
url = {https://www.osti.gov/biblio/1092347}, journal = {Physical Review C},
issn = {0556--2813},
number = 2,
volume = 87,
place = {United States},
year = {2013},
month = {1}
}