Alpha-decay of superheavy nuclei is a hot topic in nuclear physics both theoretically and experimentally. Superheavy nuclei (SHN) with atomic numbers beyond 110 predominantly undergo sequential alpha-decay and one efficient approach to identify new superheavy nucleus is the observation of alpha-decay chain. Because the experimentalists have to evaluate the values of the alpha-decay half-lives during the experimental design, it is quite important and necessary to investigate the alpha-decay of SHN theoretically.

The researchers of the theory group in Institute of Modern Physics, Chinese Academy of Sciences(IMP), have proposed a new approach for predicting the alpha-decay half-lives of SHN in terms of the correlation between the alpha-decay half-lives of neighboring SHN. By using the proposed scenario and based on the Royer's and VSS formulae. The results are found to be in excellent agreement with the experimental data (see Tab.1) which indicates the predictive power of the new method. According to the present calculations, an important conclusion is that the experimental half-lives are themselves consistent with each other confirming the reliability of the experimental observations and measurements to a great extent.

The researchers have also tested the applicability of the WKB approximation for quantum mechanical tunneling probabilities. The barrier penetrability for alpha decay, proton and cluster emission have been calculated accurately with the recursion formulae by a numerical method to solve one-dimensional Schrodinger equation for unbound state, and the results are compared with those of the WKB approximation. The relative deviation of the penetrability produced by the WKB approximation for alpha-decay is shown in Fig.1. It is found that the WKB approximation underestimates the penetrability by -40%～-30% for alpha-decay, -40%～-20% for proton emission and -5%～15% for cluster radioactivity. The deviation caused by the WKB approximation turns out to depend only weakly on atomic number for each decay mode and it can be compensated by other quantities such as a phenomenological assault frequency within the WKB framework. Therefore, the WKB method works well for these decays.

The work has been published in Nucl. Phys. A861 (2011) 1. The paper can be found on the webpage:

http://www.sciencedirect.com/science/article/pii/S0375947411004404

Tab.1 Calculated alpha-decay half-lives of SHN in comparison with the experimental data(Image by IMP)

Fig.1 Relative deviation of penetrability caused by the WKB approximation for alpha-decay(Image by IMP)