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Search Results: 1 - 10 of 9376 matches for " Jianzhong Gu "
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Coulomb Excitation of Double Giant Dipole Resonances
Jianzhong Gu,H. A. Weidenmueller
Physics , 2000, DOI: 10.1016/S0375-9474(01)00356-6
Abstract: We implement the Brink-Axel hypothesis for the excitation of the double giant dipole resonance (DGDR): The background states which couple to the one-phonon giant dipole resonance are themselves capable of dipole absorption. These states (and the ones which couple to the two-phonon resonance) are described in terms of the Gaussian Orthogonal Ensemble of random matrices. We use second-order time-dependent perturbation theory and calculate analytically the ensemble-averaged cross section for excitation of the DGDR. Numerical calculations illuminate the mechanism and the dependence of the cross section on the various parameters of the theory, and are specifically performed for the reaction $^{208}$Pb + $^{208}$Pb at a projectile energy of 640 MeV/nucleon. We show that the contribution of the background states to the excitation of the DGDR is significant. We find that the width of the DGDR, the energy-integrated cross section and the ratio of this quantity over the energy-integrated cross section for the single giant dipole resonance, all agree with experiment within experimental errors. We compare our approach with that of Carlson {\it et al.} who have used a similar physical picture.
Magnetization of neutron star matter
Jianmin Dong,Wei Zuo,Jianzhong Gu
Physics , 2013, DOI: 10.1103/PhysRevD.87.103010
Abstract: The magnetization of neutron star matter in magnetic fields is studied by employing the FSUGold interaction. It is found that the magnetic susceptibilities of the charged particles (proton, electron and muon) can be larger than that of neutron. The effects of the anomalous magnetic moments (AMM) of each component on the magnetic susceptibility are examined in detail. It is found that the proton and electron AMM affect their respective magnetic susceptibility evidently in strong magnetic fields. In addition, they are the protons instead of the electrons that contribute most significantly to the magnetization of the neutron star matter in a relative weak magnetic field, and the induced magnetic field due to the magnetization can be appear to be very large. Finally, the effect of the density-dependent symmetry energy on the magnetization is discussed.
Constraints on neutron skin thickness in 208Pb and density-dependent symmetry energy
Jianmin Dong,Wei Zuo,Jianzhong Gu
Physics , 2015, DOI: 10.1103/PhysRevC.91.034315
Abstract: Accurate knowledge about the neutron skin thickness $\Delta R_{np}$ in $^{208}$Pb has far-reaching implications for different communities of nuclear physics and astrophysics. Yet, the novel Lead Radius Experiment (PREX) did not yield stringent constraint on the $\Delta R_{np}$ recently. We employ a more practicable strategy currently to probe the neutron skin thickness of $^{208}$Pb based on a high linear correlation between the $\Delta R_{np}$ and $J-a_{\text{sym}}$, where $J$ and $a_{\text{sym}}$ are the symmetry energy (coefficient) of nuclear matter at saturation density and of $^{208}$Pb. An accurate $J-a_{\text{sym}}$ thus places a strong constraint on the $\Delta R_{np}$. Compared with the parity-violating asymmetry $A_{\text{PV}}$ in the PREX, the reliably experimental information on the $J-a_{\text{sym}}$ is much more easily available attributed to a wealth of measured data on nuclear masses and on decay energies. The density dependence of the symmetry energy is also well constrained with the $J-a_{\text{sym}}$. Finally, with a `tomoscan' method, we find that one just needs to measure the nucleon densities in $^{208}$Pb starting from $R_{m} = 7.61\pm0.04$ fm to obtain the $\Delta R_{np}$ in hadron scattering experiments, regardless of its interior profile that is hampered by the strong absorption.
Origin of symmetry energy in finite nuclei and density dependence of nuclear matter symmetry energy from measured alpha-decay energies
Jianmin Dong,Wei Zuo,Jianzhong Gu
Physics , 2012, DOI: 10.1103/PhysRevC.87.014303
Abstract: Based on the Skyrme energy density functional, the spatial distribution of the symmetry energy of a finite nucleus is derived in order to examine whether the symmetry energy of a finite nucleus originates from its interior or from its surface. It is found that the surface part of a heavy nucleus contributes dominantly to its symmetry energy compared to its inner part. The symmetry energy coefficient $a_{\text{sym}}({A})$ is then directly extracted and the ratio of the surface symmetry coefficient to the volume symmetry coefficient $\kappa$ is estimated. Meanwhile, with the help of experimental alpha decay energies, a macroscopic method is developed to determine the symmetry energy coefficient of heavy nuclei. The resultant $a_{\text{sym}}({A})$ is used to analyze the density dependence of the symmetry energy coefficient of nuclear matter around the saturation density, and furthermore, the neutron skin thickness of $^{208}\text{Pb}$ is deduced which is consistent with the pygmy dipole resonance analysis. In addition, it is shown that the ratio $\kappa$ obtained from the macroscopic method is in agreement with that from the Skyrme energy density functional. Thus the two completely different approaches may validate each other to achieve more compelling results.
The NO2 sensing ITO thin films prepared by ultrasonic spray pyrolysis
Zheng Jiao,Minghong Wu,Zheng Qin,Minghua Lu,Jianzhong Gu
Sensors , 2003, DOI: 10.3390/s30800285
Abstract: In this paper ITO thin films were deposited on alumina substrates by ultrasonic spray pyrolysis. The NO2 sensing properties of ITO thin films were investigated. The results show ITO thin films have good sensitivity to nitrogen dioxide.
Alpha-decay half-lives and Q_alpha values of superheavy nuclei
Jianmin Dong,Wei Zuo,Jianzhong Gu,Yanzhao Wang,Bangbao Peng
Physics , 2010, DOI: 10.1103/PhysRevC.81.064309
Abstract: 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.
Density dependence of nuclear symmetry energy constrained by mean-field calculations
Jianmin Dong,Wei Zuo,Jianzhong Gu,Umberto Lombardo
Physics , 2012, DOI: 10.1103/PhysRevC.85.034308
Abstract: We establish a correlation for the symmetry energy at saturation density $S_{0}$, slope parameter $L$ and curvature parameter $K_{\text{sym}}$ based on widely different mean field interactions. With the help of this correlation and available empirical and theoretical information, the density dependent behavior around the saturation density is determined. We compare the results obtained with the present approach with those by other analyses. With this obtained density dependent behavior of the symmetry energy, the neutron skin thickness of $^{208}$Pb and some properties of neutron stars are investigated. In addition, it is found that the expression $S(\rho)=S_{0}(\rho /\rho_{0})^{\gamma}$ or $S(\rho)=12.5(\rho /\rho_{0}) ^{2/3}+C_{p}(\rho /\rho_{0}) ^{\gamma}$ does not reproduce the density dependence of the symmetry energy as predicted by the mean-field approach around nuclear saturation density.
Statistical Properties of Charmonium Spectrum and a New Mechanism of J/ψSuppression
Jianzhong Gu,Hongshi Zong,Yuxin Liu,Enguang Zhao
Physics , 1999, DOI: 10.1103/PhysRevC.60.035211
Abstract: The statistical properties of Charmonium energy spectrum determined by the Bethe-Salpeter equation are investigated. It is found that the regular motion of the $c\bar{c}$ system can be expected at a small value of color screening mass but the chaotic motion at a large one. It is shown that the level mixing due to color screening serves as a new mechanism resulting in the J/$\psi$ suppression. Moreover, this kind of suppression can occur before the color screening mass reaches its critical value for J/$\psi$ dissociation. It implies that a strong J/$\psi$ suppression is possible in the absence of dissociation of J/$\psi$.
Nonlinear Modeling Approach to Human Promoter Sequences
Huijie Yang,Fangcui Zhao,Jianzhong Gu,Binghong Wang
Quantitative Biology , 2005,
Abstract: By means of the nonlinear modeling technique (NM technique), we find the nonlinear deterministic structures in the promoter regions (PPRs) of DNA sequences, called deterministic valleys (DVs) in this paper. These DVs prefer to occur much more outside of a special region around TSS. The number, positions and shapes of the DVs are basically different for different PPRs. Generally, these DVs do not occur in the CpG islands, which tells us that they should be special structures with new biological functions rather than the CpG islands. PACS numbers: 87.14.Gg, 87.10.1e, 05.45.2a
Prediction of Landscape Pattern of Soft Sandstone Area (SSA) after Seabuckthorn Planting  [PDF]
Jianzhong Hu
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.31020
Abstract: As a pioneer plant in the gully slopes in the Soft Sandstone Area (SSA) for eco-economical consideration, ten years (1999-2008) planting of seabuckthorn has made 1642.83 km2, or 9.84%, of the total area of SSA change into seabuckthorn coverage. In SSA the landscape has been divided into 9 types, such as seabuckthorn, sand, water, settlement, bush, open vegetation, forest, grassland and unused land. Seabuckthorn type is separated from the bush type for estimating the role of seabuckthron planting. By means of the Markov model, the developing trends of every landscape types can be determined to support the seabuckthorn project which influences the landscape pattern deeply in SSA. The prediction shows that the optimism ratio of seabuckthorn in the future should be 10.21%, the open vegetation 32.25%, and the forest percentage under 10%, which is a very wise tactics to avoid the serious death of various vegetations in SSA to match the local arid eco-environment.
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