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Selected issues at the interface between nuclear physics and astrophysics as well as the standard model

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中国科学：物理学、力学、天文学英文版 2011年第S1期54卷 119-123页

作者： MENG Jie1,2,3, NIU ZhongMing1, LIANG HaoZhao1 & SUN BaoHua2,4 1State Key Laboratory of Nuclear physics and Technology, school of physics, Peking University, Beijing 100871, China 2school of physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China 3Department of physics, University of Stellenbosch, Stellenbosch, South Africa 4Justus-Liebig-Universita¨t Giessen, Heinrich-Buff-Ring 14, Giessen 35392, Germany 1. State Key Laboratory of Nuclear physics and Technology School of Physics Peking University Beijing 100871 China 2. school of physics and Nuclear Energy Engineering Beihang University Beijing 100191 China 3. Department of physics University of Stellenbosch Stellenbosch South Africa 4. Justus-Liebig-Universit?t Giessen Heinrich-Buff-Ring 14 Giessen 35392 Germany

The density functional theory (DFT) with a minimal number of parameters allows a very successful phenomenological description of ground state properties of nuclei all over the periodic table. The recent developments on the application of the covariant density functional theory as well as its extensions by the group in Beijing for a series of interests and hot topics in nuclear astrophysics and nuclear structure are reviewed, including the rapid neutron-capture process, Th/U chronometer, and isospin corrections for superallowed β transitions.

关键词： rapid neutron-capture process nuclear chronometer isospin symmetry-breaking corrections

A note on the discovery of a 2M_⊙ pulsar

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Research in Astronomy and Astrophysics 2011年第6期11卷 687-691页

作者： Xiao-Yu Lai Ren-Xin Xu school of physics and State Key Laboratory of Nuclear physics and Technology Peking University Beijing 100871 China

It is conventionally thought that the state equation of dense matter softens and thus cannot result in high maximum mass if pulsars are quark stars and that a recently discovered 2M⊙ pulsar （PSR J1614–2230） may make pulsars unlikely to be quark stars. However, this standard point of view would be revisited and updated if quark clustering could occur in cold quark matter because of the strong coupling be- tween quarks at realistic baryon densities in compact stars. It can be argued that the state equation of clustered quark matter stiffens to support compact stars with maxi- mum mass Mmax 2M⊙. In this brief note, it is demonstrated that large parameter space ranges are allowed for Mmax 2M⊙ in a Lennard-Jones model of clustered quark matter and the newly measured highest mass of PSR J1614–2230 would be meaningful for constraining the number of quarks inside a single quark-cluster to be Nq ≤ 103.

关键词： dense matter — elementary particles — pulsars: general — stars: neutron

Temperature dependence of surface enhanced Raman scattering on C70

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Science Bulletin 2005年第1期50卷 1-4页

作者： GAO Ying, Zhang Zhenlong, DU Yinxiao, DONG Hua & MO Yujun school of physics and Information Optoelectronics, Henan University, Kaifeng 475001, China school of physics and Information Optoelectronics Henan University Kaifeng China

The temperature dependence of surface en-hanced Raman scattering of the C70 molecule is reported. The Raman scattering of C70 molecules adsorbed on the sur-face of a silver mirror was measured at different tempera-tures. The experimental results indicate that the relative in-tensities of the Raman features vary with the temperature of the sample. When the temperature decreases from room temperature to 0℃, the relative intensities of certain Raman bands decrease abruptly. If we take the strongest band 1565 cm-1 as a standard value 100, the greatest decrease ap-proaches to 43%. However, with the further decrease in the temperature these relative intensities increase and resume the value at room temperature. And such a temperature de-pendence is reversible. Our results show that the adsorption state of the C70 molecules on the silver surface around 0℃ changes greatly with the temperature, resulting in a decrease in relative intensities for some main Raman features of C70 molecule. When the temperature is lower than 0℃, the ad-sorption state changes continually and more slowly. Syn-chronously, eight new Raman features, which have not ever been reported in literature, are observed in our experiment and this enriches the basic information of the vibrational modes for C70 molecule.

关键词： C70 Raman spectrum temperature silver mirror fullerene.

Evidence of Positron Trapping into Defects in Zn-Doped GaAs

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Wuhan University Journal of Natural Sciences 2003年第4A期8卷 1103-1106页

作者： Wang Zhu, Zheng Zi-yao, Su Ben-fa, Hu Wei-guo school of physics and Technology, Wuhan University , Wuhan 430072, Hubei, China Wuhan University

The defect properties in as-grown and deformed p-type GaAs with different concentration of dopants and different growth method have investigated by positron lifetime measurement. The result indicates that no positron trapping was observed in LEC-grown Zn-doped p-type GaAs. However, in HB- and FZ-grown Zn-doped GaAs, positron trapping into vacancy type defects was observed. In deformed samples, clusters were formed during deformation. Positron detected shallow positron traps and the dominant shallow positron traps were attributed to Zn acceptors in Zn-doped GaAs.

关键词： positron annihilation defect semiconductor deformation p-type GaAs

An atomistic simulation of site preference and vibrational properties of UMxAl12-x (M = Fe, Co, Ni, Cr and Mn) and UMxAl12-xHx

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Progress in Natural Science:Materials International 2009年第8期19卷 983-989页

作者： Huijun Tian a,b, Ping Qian a, Jiang Shen a, Nanxian Chen a,c a Institute of Applied physics, Beijing University of Science and Technology, Beijing 100083, China b school of physics, Beijing University of Chemical Technology, Beijing 100029, China c Department of physics, Tsinghua University, Beijing 100084, China [a]Institute of Applied physics Beijing University of Science and Technology Beijing 100083 China [b]School of Physics Beijing University of Chemical Technology Beijing 100029 China [c]Department of Physics Tsinghua University Beijing 100084 China

A series of lattice inversion pair potentials are used to evaluate the phase stability and site preference for uranium intermetallics UMxAl12 x (M = Fe, Co, Ni, Cr and Mn) and their related hydrides. Calculated results show that Fe, Co, Ni, Cr or Mn atoms preferentially substitute Al at the 8f site. Interstitial H atoms only occupy 2b interstitial sites in UMxAl12 x. Calculated lattice constants are found to agree with a report in the literature. Elastic constants and bulk modulus of UMxAl12 x and UMxAl12 xH were also investigated. In particular, the phonon densities of states (DOS) of these actinide compounds were evaluated for the first time.

关键词： Interatomic potentials Site preference Lattice vibration

Convergence for Imaginary Time Step evolution in the Fermi and Dirac seas

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Science China(physics,Mechanics & Astronomy) 2010年第2期53卷 327-330页

作者： LI FangQiong1,ZHANG Ying2 & MENG Jie2,3,4 1Guizhou University for Nationalities,Guiyang 550025,China 2State Key Lab Nucl. Phys. & Tech.,school of physics,Peking University,Beijing 100871,China 3school of physics and Nuclear Energy Engineering,Beihang University,Beijing 100191,China 4Department of physics,University of Stellenbosch,Stellenbosch,South Africa 1. Guizhou University for Nationalities Guiyang 550025 China2. State Key Lab Nucl. Phys. & Tech. School of Physics Peking University Beijing 100871 China3. School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China4. Department of Physics University of Stellenbosch Stellenbosch South Africa

The convergence for the Imaginary Time Step (ITS) evolution with time step is investigated by performing the ITS evolution for the Schrdinger-like equation and the charge-conjugate Schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITS evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.

关键词： Dirac equation Schrdinger-like equation Imaginary Time Step method convergence

Laser-induced convenient fabrication of CdS nanocages with super-adsorption capability for methyl blue solution

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Chinese physics B 2017年第8期26卷 293-298页

作者：刘乐徐林林张华陈明 Shandong Univ Sch PhysJinan 250100ShandongPeoples R China

We report on the successful synthesis of cadmium sulfide （CdS） nanocages by laser ablation of bulk Cd target in thioacetamide （TAA） solution. The CdS nanocages exhibit obvious interior hollow spaces and distinctive porous-shell structures. After laser ablation of Cd target in liquid condition, the unique structure should be attributed to the initial forma- tion of Cd micro-gas bubble via a model of micro-explosive boiling model. Surprisingly, the obtained CdS nanocages can provide a super-adsorption of methyl blue （MB） solution. The maximum adsorption capacity reaches up to 11813.3 mg/g, which is much higher than that reported in many previous researches. Without using any complicated stabilizers or soft directing agents, the pure CdS nanocages fabricated by laser ablation will serve as advanced absorbents in further research.

关键词： laser-induced fabrication CdS nanocages

Surface characteristics of rapidly solidified nickel-based superalloy pow-ders prepared by PREP

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Rare Metals 2003年第4期22卷 309-314页

作者： CHEN Huanming , HU Benfu , and LI Huiying1) school of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China2) school of physics and Electrical Information Engineering, Ningxia University, Yinchuan 750021, China school of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 Chins

The surface microstructure and the surface segregation of FGH 95 nickel-basedsuperalloy powders prepared through plasma rotating electrode processing (PREP) have beeninvestigated by using SEM and AES. The results indicate that the surface microstructure of powderschanges from dendrite into cellular stricture as the particle size of powders decrease, and thepredominant precipitates solidified on the particle surfaces were identified as MC' type carbidesenriched with Nb and Ti. It was also indicated that along with the depth of particle surfaces, thesegregation layer of S, C and O elements are thick, and that of Ti, Cr elements are thin for largesire powders while they are in reverse for median size particles.

关键词： FGH 95 nickel-based superalloy powders surface characteristics microstructure plasma rotating electrode processing

Energy dissipation and angular momentum transfer within a magnetically torqued accretion disc

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Science China(physics,Mechanics & Astronomy) 2010年第S1期53卷 106-109页

作者： GAN ZhaoMing,WANG DingXiong,LEI WeiHua & LI Yang school of physics,Huazhong University of Science and Technology,Wuhan 430074,China 1. school of physics Huazhong University of Science and Technology Wuhan 430074 China

We discuss transportation and redistribution of energy and angular momentum in the magnetic connection(MC) process and Blandford-Payne(BP) *** results in readjusting the interior viscous torque,and its effects are operative not only in but also beyond the MC *** BP process is invoked to transfer the "excessive" angular momentum from an accretion *** addition,we derive a criterion for the interior viscous torque to resolve the puzzle of the overall equilibrium of angular momentum in disc *** turns out that the efficiency of BP at extracting angular momentum and the intensity of the outflow are required to be greater than some critical values.

关键词： accretion:accretion discs black hole physics magnetic field angular momentum transfer