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Collision dynamics of He@C_(60)+He@C_(60) at low energies

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Science china(physics,Mechanics & Astronomy) 2008年第7期51卷 765-772页

作者： ZHAO Qiang1,2, ZHANG FengShou1,2,3 & ZHOU HongYu1,2 1 Key laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy nuclear physics, Beijing Normal University, Beijing 100875, china 2 Beijing Radiation center, Beijing 100875, china 3 center of theoretical nuclear physics, national laboratory of heavy ion accelerator of lanzhou, lanzhou 73.000, china 1. Key laboratory of Beam Technology and Material Modification of Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. Beijing Radiation center Beijing 100875 China 3. center of theoretical nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

关键词： C60 He@C60 collision molecular dynamics

Higher order bulk characteristic parameters of asymmetric nuclear matter

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 124-129页

作者： CHEN LieWen1,2 1Department of physics, Shanghai Jiao Tong University, Shanghai 200240, china 2center of theoretical nuclear physics, national laboratory of heavy ion accelerator, lanzhou 73.000, china 1. Department of physics Shanghai Jiao Tong University Shanghai 200240 China 2. center of theoretical nuclear physics National Laboratory of Heavy Ion Accelerator Lanzhou 730000 China

The bulk parameters characterizing the energy of symmetric nuclear matter and the symmetry energy defined at normal nuclear density ρ0 provide important information on the equation of state (EOS) of isospin asymmetric nuclear matter. While significant progress has been made in determining some lower order bulk characteristic parameters, such as the energy E0(ρ0) and incompress ibility K0 of symmetric nuclear matter as well as the symmetry energy Esym(ρ0) and its slope parameter L, yet the higher order bulk characteristic parameters are still poorly known. Here, we analyze the correlations between the lower and higher order bulk char acteristic parameters within the framework of Skyrme Hartree-Fock energy density functional and then estimate the values of some higher order bulk characteristic parameters. In particular, we obtain J0 = (-355±95) MeV and I0 = (1473±680) MeV for the third order and fourth-order derivative parameters of symmetric nuclear matter at ρ0 and Ksym = (-100 ± 165) MeV, Jsym = (224 ± 385) MeV, Isym = (-1309 ± 2025) MeV for the curvature parameter, third-order and fourth-order derivative parameters of the symmetry energy at ρ0, using the empirical constraints on E0(ρ0), K0, Esym(ρ0), L, and the isoscalar and isovector nucleon effective masses. Furthermore, our results indicate that the three parameters E0(ρ0), K0, and J0 can reasonably characterize the EOS of symmetric nuclear matter up to 2ρ0 while the symmetry energy up to 2ρ0 can be well described by Esym(ρ0), L, and Ksym.

关键词： equations of state of nuclear matter forces in hadronic systems and effective interactions symmetry energy nuclear density functional theory and extensions asymmetric matter neutron matter

Profile of the composition fractions in neutron stars

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Chinese Science Bulletin 2002年第8期47卷 632-634页

作者： LI Wenfei, ZHANG Fengshou & CHEN Liewencenter of theoretical nuclear physics, national laboratory of heavy ion accelerator, lanzhou 73.000, china Institute of Modern physics, Chinese Academy of Sciences, lanzhou 73.000, china Department of physics, Shangh center of theoretical nuclear physics National Laboratory of Heavy Ion Accelerator Lanzhou China Institute of Modern physics Chinese Academy of Sciences Lanzhou China Department of physics Shanghai Jiao Tong University Shanghai China

The composition fractions of β-stable neutron stars and their radial distributions are investigated based on Skyrme-Hartree-Fock theory and Tolman-Oppenheimer-Volkoff (TOV) equation. It is found that a pure neutron interior with a radius of 3.5 km can exist in the neutron stars. When the radius is greater than 3.5 km, the fractions of the proton, electron and μ- appear and increase with the increment of the radius, then decrease after reaching their maximum at the radius of 8 km. These results make it possible to further study the thermal evolution and magnetic properties of the neutron stars.

关键词： neutron stars compositon fractions asymmetric nuclear matter equation of state Tolman-Oppenheimer-Volkoff equation.

The relativistic consistent angular-momentum projected shell model study of the N=Z nucleus ^(52)Fe

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Science china(physics,Mechanics & Astronomy) 2009年第10期52卷 1471-1476页

作者： LI YanSong1,2 & LONG GuiLu1,2 1 Department of physics,Tsinghua University,Beijing 100084,china 2 center of nuclear Theory,national laboratory of heavy ion accelerator of lanzhou,lanzhou 73.000,china 1. Department of physics Tsinghua University Beijing 100084 China 2. center of nuclear Theory National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The relativistic consistent angular-momentum projected shell model(ReCAPS) is used in the study of the structure and electromagnetic transitions of the low-lying states in the N=Z nucleus *** model calculations show a reasonably good agreement with the *** backbending at 12+ is reproduced and the energy level structure suggests that neutron-proton interactions play important roles.

关键词： ReCAPS relativistic mean field angular-momentum projection method 52Fe neutron-proton interaction

Criterion for reducible hydrodynamic equations of baryon-rich quark-gluon plasma

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nuclear Science and Techniques 2000年第1期11卷 41-44页

作者： AI Xiao-Bai (Hsiao-bat AI) (center of theoretical nuclear physics, national laboratory of heavy ion accelerator, lanzhou 73.000 Shanghai Institule of nuclear Research, the Chinese Academy of Sciences, Shanghai 201800) 兰州原子核理论研究中心重离子加速器国家实验室甘肃兰州 730000

Besides the state equation there exists another cubic algebraic equation about μf in the form of μf3 + pμf + q = 0, which relates parameters, temperature T, chemical potential μf, and net quark number nff （flavor f） for a baryon-rich quark-gluon plasma （QGP）. A criterion may be acquired simply according to Cardan formula of the solution of the above equation, which gives naturally a condition: if n ion of specific entropy, and then the set of hydrodynamic equation of baryon-rich QGP may be reduced to the set of hydrodynamic equation for baryon-free QGP.

关键词：重子夸克胶子粒子物理学简化流体动力学方程等离子体 QGP

Analysis of the negative-parity yrast band in ^(155)Tb

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nuclear Science and Techniques 2000年第1期11卷 55-59页

作者： WU Xing-Ju XU Jin-Zhang CHEN Xing-Qu (center of theoretical nuclear physics, national laboratory of heavy ion accelerator, lanzhou 73.000 physics Department,Lu-an Teacher’s College,Lu-an, Anhui 237012 Department of Modern physics, lanzhou University, 六安师范专科学校重离子加速器国家实验室安徽六安 237012 兰州大学现代物理系重离子加速器国家实验室甘肃兰州 730000

Using the particle-rotor model, the energy spectrum and the B（MI）/B（E2） ratio of the negative-parity yrast band in 155Tb are investigated and compared with the experimental data before and after the band-crossing. It is noted that before and after the band-crossing the moment of inertia of the core is a smooth function of the total angular momentum I and can be described by the ah formula. The yrast band of 155Tb with negative parity may be triaxially deformed （γ=-13°） before and an axially symmetric shape （γ=0°） after the band-crossing.

关键词：铽155 原子核高自旋态结构性质负跃迁晕转态核子

The low-lying rotational bands of the neutron-rich nucleus ^(172)Tm

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Science china(physics,Mechanics & Astronomy) 2009年第10期52卷 1542-1547页

作者： CHEN BaoRen1,LI Tao1 & LIU ShuXin1,2 1 School of physics,Peking University,Beijing 100871,china 2 center of theoretical nuclear physics,national laboratory of heavy ion Collisions,lanzhou 73.000,china School of physics Peking University Beijing 100871 China center of theoretical nuclear physics National Laboratory of Heavy Ion Collisions Lanzhou 730000 China

The microscopic mechanism of four experimentally observed bands in 172Tm is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring *** experimental results,including the moments of inertia and angular momentum alignments of four bands in 172Tm are reproduced well by the particle-number conserving *** ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are *** unobserved low-lying bands of 2-quansiparticles in 172Tm are predicted.

关键词： neutron-rich nucleus rare earth rotational band

Shell effect and capture cross sections in the synthesis of superheavy nuclei

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Science china(physics,Mechanics & Astronomy) 2009年第10期52卷 1489-1493页

作者： DU SaiSai1,2,BIAN BaoAn1,2,3,LIU Min1,2,4,FENG ZhaoQing5,6 & ZHANG FengShou1,2,6 1 Key laboratory of Beam Technology and Material Modification of Ministry of Education,College of nuclear Science and Technology,Beijing Normal University,Beijing 100875,china 2 Beijing Radiation center,Beijing 100875,china 3 School of Science,Jiangnan University,Wuxi 214122,china 4 College of physics and Technology,Guangxi Normal University,Guilin 541004,china 5 Institute of Modern physics,Chinese Academy of Sciences,lanzhou 73.000,china 6 center of theoretical nuclear physics,national laboratory of heavy ion accelerator of lanzhou,lanzhou 73.000,china Key laboratory of Beam Technology and Material Modification of Ministry of Education College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China Beijing Radiation center Beijing 100875 China School of Science Jiangnan University Wuxi 214122 China College of physics and Technology Guangxi Normal University Guilin 541004 China Institute of Modern physics Chinese Academy of Sciences Lanzhou 730000 China center of theoretical nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The shell effect is included in the improved isospin dependent quantum molecular dynamics model in which the shell correction energy of the system is calculated by using the deformed two-center shell model. A switch function is introduced to connect the shell correction energy of the projectile and the target with that of the compound nucleus during the dynamical fusion process. It is found that the calculated capture cross sections reproduce the experimental data quantitatively at the energy near the Coulomb barrier. The capture cross sections for reaction 35 80 Br + 82 208 Pb → 117 288 X are also calculated and discussed.

关键词： superheavy nuclei transport theory shell effect cross sections

Shape phase transitions in nuclei:Effective order parameters and trajectories

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Science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHANG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3 1Department of physics, Liaoning Normal University, Dalian 116029, china 2Department of physics and the State Key laboratory of nuclear physics and Technology, Peking University, Beijing 100871, china 3center of theoretical nuclear physics, national laboratory of heavy ion accelerator, lanzhou 720000, china 1. Department of physics Liaoning Normal University Dalian 116029 China2. Department of Physics and the State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China3. Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou 720000 China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory