Xiao Jun Bao

Competition between α-decay and spontaneous fission for superheavy nuclei

The α-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated by employing a unified fission model (UFM) and Royers analytical formula (2000 J. Phys. G: Nucl. Part. Phys. 26 1149). The good agreement with the experimental data indicates the UFM and the analytical formula are useful tools to investigate these α-decays. A modified formula is proposed for determining the spontaneous fission half-lives based on Swiateckis formula, including the microscopic shell correction and isospin effect.The spontaneous fission half-lives for heavy and SHN in regions from Th to Fl are calculated systematically. Experimental data are well reproduced by the modified Swiatecki formula. The competition between α-decay and spontaneous fission is analyzed in detail and the decay modes are predicted for the unknown cases.

Half-lives of cluster radioactivity with a generalized liquid-drop model

Half-lives of cluster radioactivity treated as a very asymmetric spontaneous fission are investigated within the WKB barrier-penetration probability. The potential barrier is constructed using a generalized liquid-drop model (GLDM), taking into account the nuclear proximity energy, the mass asymmetry, an accurate nuclear radius, a phenomenological pairing correction and the microscopic shell corrections. The calculated cluster emission half-lives accurately reproduce the experimental data. Predictions are provided for possible cluster radioactivity within the GLDM using the up-to-date atomic mass table AME2011, which may be used for the future experiments.

Weizsäcker–Skyrme-type mass formula by considering radial basis function correction

By incorporating with the radial basis function correction, the Weizsacker-Skyrme-type nuclear mass formula was further improved. The root-mean-square (rms) deviation of the binding energies between the theoretical calculations and 2267 experimental masses has been significantly reduced from 493 keV to 323 keV. The alpha-decay energies Q(alpha) obtained from the binding energy by this hybrid formula also become more precise, i.e. the rms deviations for the Z = 74-118 even-even isotopes and for the 46 superheavy nuclei fall from 420 keV to 161 keV and from 501 keV to 230 keV, respectively. With the above calculated Q(alpha) values as inputs, the calculated alpha-decay half-lives for the even-even (Z = 74-118) nuclei agree with the experimental ones very well, especially for the superheavy nuclei. Thus the further improved Weizsacker-Skyrme-type nuclear mass formula is useful for predicting nuclear properties associated with mass evaluation systematically.

Nucleon mean free path in asymmetric nuclear matter at finite temperature

The nucleon mean free path in symmetric and asymmetric nuclear matter is investigated in the framework of the finite temperature Brueckner theory. The realistic Bonn B two-body nucleon–nucleon interaction in combination with a consistent microscopic three-body force is adopted in the calculations. The results of the nucleon mean free path at zero temperature are in good agreement with the experimental data. The temperature and density and isospin dependence of the mean free path are studied systematically in asymmetric nuclear matter.