Observation of the Superheavy Nuclide ^(271)Ds

With the recent commissioning of a gas-filled recoil separator at Institute of Modern Physics (IMP) in Lanzhou,the decay properties of 271Ds (Z =110) were studied via the 20sPb(64Ni,n) reaction at a beam energy of 313.3 MeV.Based on the separator coupled with a position sensitive silicon strip detector,we carried out the energy-position-time correlation measurements for the implanted nucleus and its subsequent decay α's.One α-decay chain for 271Ds was established.The α energy and decay time of the 27iDs nucleus were measured to be 10.644 MeV and 96.8ms,which are consistent with the values reported in the literature.

Benford's Law and β-Decay Half-Lives

The experimental values of 2059 β-decay half-lives are systematically analyzed and investigated. We have found that they are in satisfactory agreement with Benford＇s law, which states that the frequency of occurrence of each figure, 1-9, as the first significant digit in a surprisingly large number of different data sets follows a logarithmic distribution favoring the smaller ones. Benford＇s logarithmic distribution of β-deeay half-lives can be explained in terms of Neweomb＇s justification of Benford＇s law and empirical exponential law of β-decay half-lives. Moreover, we test the calculated values of 6721 β-decay half-lives with the aid of Benford＇s law. This indicates that Benford＇s law is useful for theoretical physicists to test their methods for calculating β-decay half-lives.

Ground State Properties of Superheavy Nuclei in Macroscopic-Microscopic Model

The ground state properties of superheavy nuclei are systematically calculated by the macroscopic-microscopic (MM) model with the Nilsson potential.The calculations well produced the ground state binding energies,α-decay energies,and half lives of superheavy nuclei.The calculated results are systematically compared with availableexperimental data.The calculated results are also compared with theoretical results from other MM models and fromrelativistic mean-field model.The calculations and comparisons show that the MM model is reliable in superheavy regionand that the MM model results are not very sensitive to the choice of microscopic single-particle potential.

Coordinate Transformation and Exact Solutions of Schrodinger Equation with Position-Dependent Effective Mass

Using the coordinate transformation method, we solve the one-dimensional Schrodinger equation with position-dependent mass. The explicit expressions for the potentials, energy eigenvalues, and eigenfunctions of the systems are given. The eigenfunctions can be expressed in terms of the Jacobi, Hermite, and generalized Laguerre polynomials. All potentials for these solvable systems have an extra term Vm, which is produced from the dependence of mass on the position, compared with those for the systems of constant mass. The properties of Vm for several mass functions are discussed.

Theoretical Study on Alpha-Decay Chains of 294 117 117 and 293 176 117

The newly synthesized element 117 and its alpha-decay chains are systematically investigated in the framework of the relativistic mean field theory with parameter sets NL-Z2 and TMA. The ground-state properties of the superheavy nuclei on the alpha-decay chains of 294 117 and 293 117 are calculated. The experimental alpha-decay energies and ha Jr-lives of the two alpha-decay chains are reasonably reproduced by the model The detailed discussions on the binding energies, alpha-decay energies, half-lives, quadrupole deformations, potential energy curves, and single particle levels of the two alpha-decay chains are made.

Theoretical Study on N=126 Shell Evolution

The nuclei around magic number N=126 are investigated in the deformed relativistic mean field (RMF)model with effective interactions TMA.We focus investigations on the N=126 isotonic chain.The N=126 shellevolution is studied by analyzing the variations of two-neutron (proton) separation energies,quadruple deformations,single particle levels etc.The good agreement of two-neutron separation energies between experimental data and calculatedvalues is reached.The RMF theory predicts that the sizes of N=126 shell become smaller and smaller withthe increasing of proton number Z.However,the N=126 shell exists in our calculated region all along.According tothe calculated two-proton separation energies,the RMF theory suggests ^(220)Pu is a two-proton drip-line nucleus in theN=126 isotonic chain.

Generalized Harmonic Oscillator and the Schrdinger Equation with Position-Dependent Mass

We study the generalized harmonic oscillator that has both the position-dependent mass and the potential depending on the form of mass function in a more general framework. The explicit expressions of the eigenvalue and eigenfunction for such a system are given, they have the same forms as those for the usual harmonic oscillator with constant mass. The coherent state and its properties corresponding effective potentials for several mass functions, for the system with PDM are also discussed. We give the the systems with such potentials are isospectral to the usual harmonic oscillator.

Anomalously Large Deformation in Some Medium and Heavy Nuclei

We investigate the properties of the Ce isotopes with neutron number N =60 - 90 and the properties of the heavy nuclei near 242Am within the framework of deformed relativistic mean-field （RMF） theory. A systematic comparison between theoretical results and experimental data is made. The calculated binding energies, two-neutron separation energies, and two-proton separation energies are in good agreement with experimental ones. The variation trend of experimental quadrupole deformation parameters on the Ce isotopes can be approximately reproduced by the RMF model. It is found that there exists an abnormally large deformation in the ground state of proton-rich Ce isotopes. This phenomenon can be the general behavior of proton-rich nuclei on the neighboring isotopic chains such as Nd and Sin isotopes. For the heavy nuclei near ^242 Am the properties of the ground state and superdeformed isomeric state can be approximately reproduced by the RMF model. The mechanism of the appearance of anomalously large deformation or superdeformation is analyzed and its influence on nuclear properties is discussed. Parther experiments to study the anomalously large deformation in some proton-rich nuclei are suggested.

Properties of A=7-9 Drip-Line Nuclei in RMF Theory

The relativistic mean-field （RMF） theory is used to calculate the properties of A =7-9 drip-line nuclei ^7Li, ^7;9Be, ^8;9B, and ^9C. Systematic deviations between experimental and theoretical binding energies are found. Possible reasons of these systematic deviations are discussed in terms of pairing energy. The root-mean-square （rms） radii of matter distributions for these nuclei agree with the experimental data quite well. The one-proton halo structure in ^8B is reproduced well, and the two-proton halo in ^9C is predicted. The calculations show that the RMF theory is valid in studying the properties of light drip-line nuclei.

Description of N=7～9 Isotones with a Modified Single-Particle Potential

We study the level structures of N = 7 - 9 isotones and their mirror nuclei in the framework of the single-particle potential model. Considering the limitation of the conventional potential-model calculation, the isospindependent 12 coupling is newly introduced in the average potential. The modified model gives a unified description for the structures of all studied nuclei. Galculations self-consistently produce the s-d level inversion in N = 9 isotones and their mirror nuclei. Meanwhile, the s-p level inversion in the mirror nuclei ^11Be and ^11N is reproduced. The study confirms the neutron halo structures in ^11Be（2s1/2）, ^11Be（1p1/2）, ^12B（2s1/2）, ^14B（2s1/2）, ^13C（2sl/2）, ^15C（2s1/2） and the proton halo structure in ^17F（2s1/2）. The agreement between theory and experiment indicates that the inclusion of the i2 coupling is a feasible way to explain the abnormal structures of exotic light nuclei.

Bound 0^(+) Excited States of Three-Body Systems with Short-Range Two-Body Interactions

The Faddeev equations are solved to investigate the bound states of three-body systems with short-range two-body interactions. Different bound 0^(+) excited states are obtained depending on the mass ratios of particles, when there is no bound state for two-body sub-systems. On the one hand, a number of bound 0^(+) excited states appear in the system with two heavy particles and a light particle. On the other hand, a weakly bound 0^(+) excited state is obtained in the system with two light particles and a heavy particle, which has not been reported in previous works as far as we know.

Alpha-Decay Study of Unfavored Transitions in Bismuth Isotopes

The unfavoredαtransitions of bismuth isotopes,including the newly observedα-decay fine structure in 209Bi[Beeman et al.,Phys.Rev.Lett.108(2012)062501]are investigated by the generalized density-dependent cluster model(GDDCM).Instead of the Wentzel-Kramers-Brillouin barrier penetration probability,the exact solution of the Schr?dinger equation under outgoing Coulomb wave boundary conditions is presented.The calculatedα-decay half-lives are found to be in good agreement with the experimental data for both odd-A and odd-odd nuclei.This indicates that the GDDCM has good applicability for unfavoredαtransitions in addition to favored ones.Some predictions onα-decay half-lives are also made for reference in future experiments.

Effect of Short-Range and Tensor Force Correlations on High-Density Behavior of Symmetry Energy

The effect of short-range and tensor correlations on nuclear symmetry energy is investigated by using realistic nuclear momentum distribution n(k).For finite nuclei,the n(k)is discussed in detail within an analytical model that allows inclusion of both short-range and tensor correlation effects in a physically very transparent way.The equation of state of symmetric nuclear matter is calculated by using realistic n(k)parameterization.The tensor-force induced short-range correlations are shown to have a significant impact on the behavior of symmetry energy.

Deformed-Skyrme-Hartree-Fock Calculation on C Isotope

The ground state properties of deformed nuclei of C isotope are investigated by the Skyrme-Hartree-Fock theory with new force parameters SKI4 of Reinhard and Flocard[Nucl.Phys.A 584(1995)467].Calculations show that the deformed-Skyrme-Hartree-Fock theory with above force parameters provides a good description on the binding energy,the various radii and deformation parameters of C isotope.The figure of the evolution of deformation for whole C isotope chain is plotted.A detailed discussion on numerical results is provided in the paper.

Ground State Properties of Z=114 Isotopes in the Relativistic Mean-Field Theory

The ground state properties of even-even Z=114 nuclei have been investigated in the relativistic mean-field theory with inclusion of deformations.The calculated binding energies agree well with values from macroscopic mass models.Calculations show that there exists a spherical shell.at N=184,because the quadrupole deformation at N=184 is zero.For nuclei near N=162,there are small prolate deformations.

Quantum Inequality Bounds for Free Rarita-Schwinger Field in Flat Spacetime

Although quantum field theory allows the local energy density negative, it also places severe restrictions on the negative energy. One of the restrictions is the quantum energy inequality （QEI）, in which the energy density is averaged over time, or space, or over space and time. By now temporal QEIs have been established for various quantum fields, but less work has been done for the spacetime quantum energy inequality. In this paper we deal with the free Rarita-Schwinger field and present a quantum inequality bound on the energy density averaged over space and time. Comparison with the QEI for the Rarita-Schwinger field shows that the lower bound is the same with the QEI. At the same time, we find the quantum inequality for the Rarita-Schwinger field is weaker than those for the scalar and Dirac fields. This fact gives further support to the conjecture that the more freedom the field has, the more easily the field displays negative energy density and the weaker the quantum inequality becomes.