Abstract
Weak decays in superheavy nuclei with proton numbers Z=118−120 and neutron numbers N=175−184 are studied within a microscopic formalism based on deformed self-consistent Skyrme Hartree-Fock mean-field calculations with pairing correlations. The half-lives of β+ decay and electron capture are compared with α-decay half-lives obtained from phenomenological formulas. The sensitivity of the half-lives to the unknown Q-energies is studied by comparing the results obtained from different approaches for the masses. It is shown that α-decay is always dominant in this mass region. The competition between α and β+/EC decay modes is studied in seven α-decay chains starting at different isotopes of Z=118, 119, and 120.
Highlights
The last decades have witnessed a lot of progress in the search and discovery of increasingly heavy elements and it is nowadays a very fruitful line of research [1,2,3,4,5]
Superheavy nuclei (SHN) with Z = 107 − 113 were synthesized from cold-fusion reactions by using target nuclei 208Pb and 209Bi and medium-mass stable isotopes of Ti, Cr, Fe, Ni, and Zn as projectiles [1,2,6]
Hot-fusion reactions involving long-lived actinide nuclei from 238U to249Cf as targets and the double magic nucleus 48Ca as projectiles were carried out to produce SHN with Z =112–118 in the neutron-evaporation channels [2,7,8,9]
Summary
The last decades have witnessed a lot of progress in the search and discovery of increasingly heavy elements and it is nowadays a very fruitful line of research [1,2,3,4,5]. The β+/EC -decay in SHN may open new pathways towards the predicted region of stability [26,27] This possibility is being studied experimentally [28,29]. The nuclear matrix elements of these transitions were assumed to be a constant value phenomenologically determined and valid for all nuclei This value can vary by almost two orders of magnitude (from log( f t) = 4.7 up to log( f t) = 6.5), depending on the reference. Half-lives for β+/EC -decay were evaluated within a proton-neutron quasiparticle random-phase approximation (pnQRPA) based on a phenomenological folded-Yukawa singleparticle Hamiltonian [33]. The method of calculation of the weak decays is based on the pnQRPA approach with a microscopic nuclear structure calculation consisting on a deformed self-consistent HartreeFock calculation with Skyrme interactions and pairing correlations in the BCS approximation (HF+BCS)
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