Deformed odd-mass nuclei are ideal examples where the interplay between single-particle and collective degrees of freedom can be studied. Inspired by the recent experimental high-spin data in the odd-proton nuclide 171 Tm, we perform projected shell model(PSM) calculations to investigate structure of the ground band and other bands based on isomeric states. In addi- tion to the usual quadrupole-quadrupole force in the Hamiltonian, we employ the hexadecapole-hexadecapole(HH) interac- tion, in a self-consistent way with the hexadecapole deformation of the deformed basis. It is found that the known experi- mental data can be well described by the PSM calculation. The effect of the HH force on the quasiparticle isomeric states is discussed.
The N≈Z nuclei in the mass A^80 region has been researched because of an abundance of nuclear structure phenomena.The projected shell model(PSM)was adopted to investigate the structure of high spin state in proton-rich 74,76,78Kr isotopes including yrast spectra,moment of inertia,electric quadrupole transitions and the behavior of single particle.The calculated results are in good agreement with available data and the shape coexistence in low-spin is also discussed.
The time evolution of protons and 3He fragments from Au＋Au/Pb＋Pb reactions at 0.25, 2, and 20 GeV/nucleon is investigated with the potential version of the Ultrarelativistic Quantum Molecular Dynamics （UrQMD） model combined with the traditional coalescence afterburner. In the coalescence process, the relative distance R0 and relative momentum P0 are surveyed in the range of 3-4 fm and 0.25-0.35 GeV/c, respectively. For both clusters, a strong reversed correlation between R0 and Po is seen and it is time-dependent as well. For protons, the accepted （R0, P0） bands lie in the time interval 30-60 fm/c, while for 3He, a longer time evolution （at about 60-90 fm/c） is needed. Otherwise, much smaller R0 and P0 values should be chosen. If we further look at the rapidity distributions from both central and semi-central collisions, it is found that the accepted [tout, （R0, P0）] assemble can provide consistent results for proton yield and collective flows especially at mid-rapdities, while for 3He, the consistency is destroyed at both middle and projectile-target rapidities.
A potential version of the UrQMD （UrQMD/M） transport model and a traditional coalescence model are combined to calculate the production of 3He fragments in central Pb＋Pb collisions at SPS energies 20-80 GeV/nucleon. It is found that the Lorentz transformation in the afterburner influences visibly the 3He yield and should be considered in calculations. The rapidity distribution of 3He multiplicities （including the concave shape） can be described well with UrQMD/M when it stops during tout=（100＋25） fm/c and the coalescence afterburner with one parameter set of （R0,P0）=（3.8 fm, 0.3 GeV/c） is taken into use afterwards.
Qing Feng LiYong Jia WangXiao Bao WangCai Wan Shen
The projected total energy surface(PTES)approach has been developed based on the triaxial projected shell model(TPSM)hybridized with the macroscopic–microscopic method.The total energy of an atomic nucleus is decomposed into macroscopic,microscopic and rotational terms.The macroscopic and microscopic components are described with the liquid drop model and Strutinsky method,respectively,and the rotational energy is given by the TPSM,the term beyond the mean field.To test theory,the PTES calculations have been carried out for the yrast states of the well deformed rare earth nucleus172W,and the theoretical results are in good agreement with the experimental data.By using the equilibrium quardrupole deformations(ε2andγ)determined by the PTES,the calculation of the transition quardrupole moment(Qt)in function of spin also reproduces the experimental data.A comparison between the PTES and TRS methods has been made for theoretical and application uses.
Inspired by the recent experimental identification of the new isomer with a half-life of （620±150） ns in the very neutron-rich nucleus 180SZr, we apply the projected shell model with axially-deformed bases to discuss possible shapes near the ground state and the nature of the isomer. The structure of the new isomer is investigated by restricting the calculation to prolate and oblate shapes. It is shown that the isomer can be understood as a K-isomer. Meanwhile, the calculation predicts more low-lying high-K configurations, which may be confirmed by future experiments,
In this review article,we first briefty introduce the transport theory and quantum molecular dynamics model applied in the study of the heavy ion collisions from low to intermediate energies.The developments of improved quantum molecular dynamics model(ImQMD)and ultra-relativistic quantum molecular dynamics model(UrQMD),are reviewed.The reaction mechanism and phenomena related to the fusion,multinucleon transrer,fragmentation,collective flow and particle production are reviewed and discussed within the framework of the two models.The constraints on the isospin asymmetric muclear equation of state and in-medium nucleon nucleon cross sections by comparing the heavy ion collision data with transport models calculations in last decades are also discussed,and the uncertainties of these constraints are analyzed as well.Finally,we discuss the future direction of the development of the transport models for improving the understanding of the reaction mechanism,the descriptions of various observables,the constraint on the nuclear equation of state,as well as for the constraint on in-medium nucleon-nucleon cross sections.
Ying-Xun ZhangNing WangQing-Feng LiLi OuJun-Long TianMin LiuKai ZhaoXi-Zhen WuZhu-Xia Li
The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.
Fragment mass distributions of quasifission induced by 238U on 160, 26Mg, 32S, 35C1, 40Ca and 65Zn targets at several bombarding energies have been calculated with the two-step model. The experimental data are reproduced consistently, and the mechanism of the distribution shape is also analyzed by investigating the different incident channels.
