Spontaneous fission modes and lifetimes of superheavy elements in the nuclear density functional theory
Abstract
Background: The reactions with the neutronrich ^{48}Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104118. The unambiguous identification of the new isotopes, however, still poses a problem because their αdecay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between αdecay 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 selfconsistent calculations of the competing decay modes of eveneven SH isotopes with 108≤Z≤126 and 148≤N≤188.Methods: We use the stateoftheart computational framework based on selfconsistent symmetryunrestricted 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 timedependent HartreeFockBogoliubov (HFB) approach. This paper constitutes a systematic selfconsistent 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 shortestlived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by ^{280}Hs, ^{284}Fl, and _{118}^{284}Uuo that separates the regions of SH nuclei synthesized in “coldfusion” and “hotfusion” reactions. The region of longlived SH nuclei is expected to be centered on ^{294}Ds with a total halflife of ∼1.5days. Our survey provides a solid benchmark for the future improvements of selfconsistent SF calculations in the region of SH nuclei.
 Publication:

Physical Review C
 Pub Date:
 February 2013
 DOI:
 10.1103/PhysRevC.87.024320
 arXiv:
 arXiv:1208.1215
 Bibcode:
 2013PhRvC..87b4320S
 Keywords:

 24.75.+i;
 25.85.Ca;
 21.60.Jz;
 27.90.+b;
 General properties of fission;
 Spontaneous fission;
 HartreeFock and randomphase approximations;
 220<
 =A;
 Nuclear Theory;
 Nuclear Experiment
 EPrint:
 6 pages, 4 figures