Yan-Zhao Wang

Branching ratios of {alpha} decay to excited states of even-even nuclei

Branching ratios of α-decay to members of the ground state rotational band and excited 0 states of even-even nuclei are calculated in the framework of the generalized liquid drop model (GLDM) by taking into account the angular momentum of the α-particle and the excitation probability of the daughter nucleus. The calculation covers isotopic chains from Hg to Fm in the mass regions 180 < A < 202 and A≥ 224. The calculated branching ratios of the α-transitions are in good agreement with the experimental data and some useful predictions are provided for future experiments.

Alpha-decay half-lives and Q_alpha values of superheavy nuclei

The alpha-decay half-lives of recently synthesized superheavy nuclei (SHN) are investigated based on a unified fission model (UFM) where a new method to calculate the assault frequency of alpha-emission is used. The excellent agreement with the experimental data indicates the UFM is a useful tool to investigate these alpha-decays. It is found that the half-lives become more and more insensitive to the Q_alpha values as the atomic number increases on the whole, which is favorable for us to predict the half-lives of SHN. In addition, a formula is suggested to compute the Q_alpha values for the nuclei with Z > 92 and N > 140 with a good accuracy, according to which the long-lived SHN should be neutron rich. With Q_alpha values from this formula as inputs, we predict the half-lives of isotopes of Z = 117, which may be useful for experimental identication in the future.

Effects of tensor interaction on pseudospin energy splitting and shell correction

In the framework of a Skyrme-Hartree-Fock approach combined with Bardeen-Cooper-Schrieffer (BCS) method, the role of the tensor force on the pseudospin energy splitting for tin isotope chain is investigated. The tensor force turns out to obviously affect the pseudospin energy splitting of the spin-unsaturated nuclei. Since the tensor force shifts the single-particle levels, it modifies the single-particle level density and the shell correction energy thereof. The influence of the tensor interaction on shell correction energy is considerable according to our analysis taking a magic nucleus {sup 132}Sn as well as a superheavy nucleus {sup 298}114 as examples. This modification of the shell correction energy due to the tensor component affects the stability of the superheavy nuclei.

ALPHA DECAY HALF-LIVES OF EXOTIC NUCLEI AROUND SHELL CLOSURES

In the framework of the generalized liquid drop model (GLDM) and improved Royers formula with a set of new coefficients derived by N. D. Schubert et al. [Eur. Phys. J. A42 (2009) 121], the favored and unfavored α-decay half-lives of exotic nuclei around closed shells Z = 82 and N = 126 are investigated. The calculated results are in good agreement with the experimental data. It is shown that our method can be used to study the α-decay half-lives of exotic nuclei around shell closures successfully and is helpful for future research on superheavy nuclei around the next proton and neutron shell closures. In addition, some α-decay half-lives for the cases where the experimental values are unavailable are predicted. We hope our predicted results are useful for future experiments.

Correlation between muonic levels and nuclear structure in muonic atoms

Abstract A method that deals with the nucleons and the muon unitedly is employed to investigate the muonic lead, with which the correlation between the muon and nucleus can be studied distinctly. A “kink” appears in the muonic isotope shift at a neutron magic number where the nuclear shell structure plays a key role. This behavior may have very important implications for the experimentally probing the shell structure of the nuclei far away from the β -stable line. We investigate the variations of the nuclear structure due to the interaction with the muon in the muonic atom and find that the nuclear structure remains basically unaltered. Therefore, the muon is a clean and reliable probe for studying the nuclear structure. In addition, a correction that the muon-induced slight change in the proton density distribution in turn shifts the muonic levels is investigated. This correction to muonic level is as important as the Lamb shift and high order vacuum polarization correction, but is larger than anomalous magnetic moment and electron shielding correction.

Tensor force effect on incompressibility of bubble nucleus

The tensor force effect on the isoscalar giant monopole resonance (ISGMR) of 46Ar is investigated in the framework of Hartree–Fock (HF) + random phase approximation (RPA) approach with the Skyrme interactions SLy5, SLy5+T and SLy5+Tw. By using the ISGMR excitation energy, the incompressibility value of 46Ar is extracted. It is shown that the incompressibility is enhanced with the SLy5+T interaction compared to the one with the SLy5 interaction. However, the SLy5+Tw interaction makes the incompressibility smaller because of the bubble structure of 46Ar.

Fine structure of alpha decay to rotational states of heavy nuclei

To gain a better insight into alpha-decay fine structure, we calculate the relative intensities of alpha decay to 2{sup +} and 4{sup +} rotational states in the framework of the generalized liquid drop model (GLDM) and improved Royers formula. The calculated relative intensities of alpha decay to 2{sup +} states are in good agreement with the experimental data. For the relative intensities of alpha decay to 4{sup +} states, a good agreement with experimental data is achieved for Th and U isotopes. The formula we obtain is useful for the analysis of experimental data of alpha-decay fine structure. In addition, some predicted relative intensities which are still not measured are provided for future experiments.