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共有20条相似文献,以下是第1-20项 搜索用时 93 毫秒

1.  Isoscaling behavior studied by HIPSE model  
   傅瑶  方德清  马余刚  蔡翔舟  郭威  马春旺  田文栋  王宏伟  王鲲《中国物理C(英文版)》,2009年第33卷第Z1期
   The isoscaling behavior in the reaction system of 58,64Ni + 9Be has been studied by using the heavy-ion phase-space exploration(HIPSE) model. The extracted isoscaling parameters α and β for both heavy and light fragments for HIPSE model calculations are in good agreement with recent experimental data. The investigation shows that the parameters in the HIPSE model have some effect on the isoscaling parameter. The isoscaling parameters for hot and cold fragments have been extracted.    

2.  Isoscaling behavior studied by HIPSE model  
   傅瑶  方德清  马余刚  蔡翔舟  郭威  马春旺  田文栋  王宏伟  王鲲《中国物理 C》,2009年第33卷第Z1期
   The isoscaling behavior in the reaction system of 58,64Ni+9Be has been studied by using the heavy-ion phase-space exploration(HIPSE) model. The extracted isoscaling parameters α and β for both heavy and light fragments for HIPSE model calculations are in good agreement with recent experimental data. The investigation shows that the parameters in the HIPSE model have some effect on the isoscaling parameter. The isoscaling parameters for hot and cold fragments have been extracted.    

3.  Isoscaling Behavior in ^48,40Ca+^9Be Collisions at Intermediate Energy Investigated by the HIPSE Model  
   傅瑶  方德清  马余刚  蔡翔舟  田文栋  王宏伟  郭威《中国物理快报》,2009年第8期
   The fragment production cross sections for 140 Me V/nucleon ^48,40 Ca^+9 Be reactions are calculated by the heavyion phase space exploration (HIPSE) model. Isoscaling behavior is observed. The isoscaling parameters a and β for both heavy and light fragments from the HIPSE model calculations are in good agreement with the experimental data. It is shown that the potential parameters in the HIPSE model have very little effect on the isoscaling parameters. The effect of the excitation energy and evaporation on the isoscaling behavior is also discussed.    

4.  Isoscaling in Statistical Sequential Decay Model  
   田文栋 马余刚 蔡翔舟 方德清 郭威 马春旺 刘贵华 沈文庆 石钰 苏前敏 王宏伟 王鲲 颜廷志《中国物理快报》,2007年第24卷第2期
   A sequential decay model is used to study isoscaling, i.e. the factorization of the isotope ratios from sources of different isospins and sizes over a broad range of excitation energies, into fugacity terms of proton and neutron number, R21(N, Z) = Y2( N, Z)/Y1( N, Z) = Cexp(αN -βZ). It is found that the isoscaling parameters α and β have a strong dependence on the isospin difference of equilibrated source and excitation energy, no significant influence of the source size on α andβ has been observed. It is found that α and β decrease with the excitation energy and are linear functions of 1/T and △(Z/A)2 or△(N/A)2 of the sources. Symmetry energy coefticient Gsym is constrained from the relationship of a and source △(Z/A)2, /3 and source △(N/A)2.    

5.  Isoscaling of the Fission Fragments with Langevin Equation  
   王鲲 马余刚 魏义彬 蔡翔舟 陈金根 方德清 郭威 马国亮 沈文庆 田文栋 钟晨 周星飞《中国物理快报》,2005年第22卷第1期
   The Langevin equation is used to simulate the fission process of ^112Sn ^112Sn and ^116Sn ^116Sn. The mass distribution of the fission fragments are given by assuming the process of symmetric fission or asymmetric fission with the Gaussian probability sampling. The isoscaling behaviour has been observed from the analysis of fission fragments of both the reactions, and the isoscaling parameter α seems to be sensitive to the width of fission probability and the beam energy.    

6.  Projectile fragment emission in the fragmentation of 56Fe on C,Al and CH2 targets at 471 A MeV  
   李彦晶  张东海  晏世伟  王立春  程锦霞  李俊生  S. Kodaira  N. Yasuda《中国物理C(英文版)》,2014年第1期
   The emission angle and the transverse momentum distributions of projectile fragments produced in the fragmentation of 56Fe on CHs, C and A1 targets at 471 A MeV are measured. It is found that for the same target, the average value and width of the angular distribution decrease with an increase of the projectile fragment charge; for the same projectile fragment, the average value of the distribution increases and the width of the distribution decreases with increasing the target charge number. The transverse momentum distribution of a projectile fragment can be explained by a single Gaussian distribution and the averaged transverse momentum per nucleon decreases with the increase of the charge of projectile fragment. The cumulated squared transverse momentum distribution of a projectile fragment can be explained well by a single Rayleigh distribution. The temperature parameter of the emission source of the projectile fragment, calculated from the cumulated squared transverse momentum distribution, decreases with the increase of the size of the projectile fragment.    

7.  Production of helium projectile fragments in {16O-emulsion interactions at 4.5 A GeV/c  
   张东海  李振宇  李俊生  吴凤娟《中国物理》,2004年第13卷第8期
   The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O-Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O-Em interactions at different energies exhibit Koba-Nielson-Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions.    

8.  Isoscaling Behaviour in the Isospin-Dependent Quantum Molecular Dynamics Model  
   田文栋 马余刚 蔡翔舟 陈金根 陈金辉 方德清 郭威 马春旺 马国亮 沈文庆 王鲲 魏义彬 颜廷志 钟晨 左嘉旭《中国物理快报》,2005年第22卷第2期
   The isoscaling behaviour is investigated in a frame of isospin-dependent quantum molecular dynamics models. The isotopic yields ratio Y2/Y1 for reactions ^48Ca ^48Ca and ^40 Ca ^4oCa at different entrance channels are simulated and presented, the relationship between the isoscaling parameter and the entrance channel is analysed, the results show that a and β reduce with the rise of incident energies and increase with the impact parameter b, which can be attributed to the temperature varying of the pre-fragments in different entrance channels. The relation of a and symmetry-term coefficient Csym reveals that the chemical potential difference △μ is sensitive to thesymmetry-term coefficient Csym, and raises with the increasing Csym.    

9.  Preparation and Reactions of Amino Acid Ester Sulfones as New Remote Asymmetrical Induced Reagents  
   ZHOU  Cheng-He  BAI  Xue  LI  Tan-Qing  WU  Jun  Alfred Hassner《有机化学》,2004年第24卷第Z1期
   The development of chiral auxiliary-controlled asymmetric synthesis has been receiving increasing interest in recent yearsfi,2] Various chiral auxiliary reagents have been observed[3] and a lot of results showed that variation of the chiral auxiliary could influence asymmetric induction. Recently, it has been reported the reaction of the aminated sulfones as a remote chiral auxiliary with α,β-unsaturated carbonyl compounds.[4] Here we would like to report the preparation of amino acid ester sulfones as new remote asymmetrical induced reagents and their reactions with α,β-unsaturated esters.    

10.  DSC study of cold and heat denaturation processes of β-lactoglobulin A with guanidine hydrochloride  
   王邦宁  谈夫《中国科学B辑(英文版)》,1997年第3期
   The cold and heat denaturations of bovine β-lactoglobuhn A (β-lg A) has been studied in solutions of guanidine hydrochloride (GuHCl) by differential scanning calorimelry (DSC) The experimental results are presented and discussed.It is shown that the number of protons bound by the monomeric molecules of β-lg A was unchanged before and after its heat denaturation below pH 3,and that the activation energy of the heat denaturation was depressed owing to the presence of GuHCl.In the solutions with 2.50 and 3.06 mol/L of GuHCl,both the cold and heat denat-urations of β-lg A were observed.In comparison with the heat denaturation,the activation energy of cold denaturation was far lower and the number of GuHCl molecules bound by the unfolded polypeptide chains after cold denaturation increased a lot.The absolute value of the enthalpy of cold denaturation was larger than that of heat denaturation It was found by the analysis that the contribution to the total denaturational enthalpy of conformational change i    

11.  Projectile fragment emission in the fragmentation of 56Fe on C,Al and CH2 targets at 471 A MeV  
   李彦晶  张东海  晏世伟  王立春  程锦霞  李俊生  S. Kodaira  N. Yasuda《中国物理 C》,2014年第38卷第1期
   The emission angle and the transverse momentum distributions of projectile fragments produced in the fragmentation of 56Fe on CH2, C and Al targets at 471 A MeV are measured. It is found that for the same target, the average value and width of the angular distribution decrease with an increase of the projectile fragment charge; for the same projectile fragment, the average value of the distribution increases and the width of the distribution decreases with increasing the target charge number. The transverse momentum distribution of a projectile fragment can be explained by a single Gaussian distribution and the averaged transverse momentum per nucleon decreases with the increase of the charge of projectile fragment. The cumulated squared transverse momentum distribution of a projectile fragment can be explained well by a single Rayleigh distribution. The temperature parameter of the emission source of the projectile fragment, calculated from the cumulated squared transverse momentum distribution, decreases with the increase of the size of the projectile fragment.    

12.  Simple Approach to the Solution of a Trapped and Radiated Cold Ion Beyond the Lamb—Dicke Limit  
   FENGMang SHILei 等《理论物理通讯》,2002年第37卷第4期
   Trapping ions outside the Lamb-Dicke limit have been proven to be useful for the laser-cooling and quantum computing.Under the supposition of the Radi frequency much smaller than the Lamb-Dicke parameter,we can use a simple method to analytically solve the system with a single cold ion trapped and radiated beyond the Lamb-Dicke limit,in the absence of the rotating-wave approximation(RWA).Discussion has been made for the limitation of our approach and the comparison of our results with the solutions under the RWA.    

13.  Isospin dependence of nuclear multifragmentation in statistical model  
   张蕾  谢东珠  张艳萍  高远《中国物理 C》,2011年第35卷第6期
   The evolution of nuclear disintegration mechanisms with increasing excitation energy, from compound nucleus to multifragmentation, has been studied by using the Statistical Multifragmentation Model (SMM) within a micro-canonical ensemble. We discuss the observable characteristics as functions of excitation energy in multifragmentation, concentrating on the isospin dependence of the model in its decaying mechanism and break-up fragment configuration by comparing the A0=200, Z0=78 and A0=200, Z0=100 systems. The calculations indicate that the neutron-rich system (Z0=78) translates to a fission-like process from evaporation later than the symmetric nucleus at a lower excitation energy, but gets a larger average multiplicity as the excitation energy increases above 1.0 MeV/u.    

14.  Density and Symmetric Potential Dependences of Isoscaling Behaviour in the Lattice Gas Model  
   SU Qian-Min  MA Yu-Gang  TIAN Wen-Dong  FANG De-Qing  CAI Xiang-Zhou  WANG Kun《中国物理快报》,2008年第25卷第6期
   Isoscaling behaviour of the statistical emission fragments from the equilibrated sources with Z=30 and N=30, 33, 36 and 39 is investigated in the framework of the isospin-dependent lattice gas model. The dependences of isoscaling parameters α on source isospin asymmetry, temperature andfreeze-out density are studied, and the `symmetry energy' is deduced from isoscaling parameters. The results show that symmetry energy Csym is insensitive to the change of temperature but follows the power-law dependence on the freeze-out density ρ. The effect of strength of asymmetry of nucleon--nucleon interaction potential on the density dependence of the symmetry energy is discussed.    

15.  Isoscaling Parameter α as a Possible Probe of Medium Effect of Nucleon--Nucleon Cross Section  
   刘建业 郝焕锋 邢永忠 左维 李希国《中国物理快报》,2007年第24卷第7期
   The medium effect of nucleon-nucleon cross section reed σ^medNN (αm) on the isoscaling parameter α is investigated for two central nuclear reactions ^40 Ca+ ^40Ca, ^60Ca+^60Ca within isospin-dependent quantum molecular dynamics at beam energies from 40 to 50 MeV/nucleon. It is found that there is the very obvious medium effects of nucleonreed nucleon cross section σ^medNN (αm) on the isoscaling parameters a. In this case the isoscaling parameter a is a possible probe of the medium effect of nucleon-nucleon cross section σ^medNN (αm) in the heavy ion collisions. The mechanism of the above-mentioned properties is studied and discussed.    

16.  Electromagnetic dissociation of 3.7 A GeV^16O in nuclear emulsion  
   李俊生  张东海  李振宇  吴凤娟《中国物理》,2004年第13卷第6期
   The electromagnetic dissociation (ED) of 3.7 A GeV {}^{16}O in nuclear emulsion is investigated with high statistics. It is found that the electromagnetically dissociated cross section increases with increasing beam energy, the charge distribution of projectile fragments is the same as the results at 60 and 200 A GeV, and the production probability of projectile fragments with charge 3≤Z≤5 is less than that of the other projectile fragments. These results can be well explained by use of Weizsacker and Williams method for calculating the ED contributions. The percentile abundance of various decay modes for ED at 3.7 A GeV is close to the result at 60 and 200 A GeV, but it is different from the result at 14.6 A GeV. The ED of 3.7 A GeV is mainly caused by the giant dipole and quadrupole resonance of E1 and E2, which can be qualitatively explained by the multiplicity distribution of projectile proton in ED. The multiplicity distribution of the α fragments in ED and nuclear events have different functional forms. This difference may be a consequence of the different reaction mechanism involved.    

17.  Two—phase flow in correlated pore—throat random porous media  
   田巨平  姚凯伦《中国物理》,2002年第11卷第4期
   We have constructed a porous media model in which there are percolation clusters with varying percolation probability P and correlated site-bonds. Taking into account both the pore and the throat geometry, the viscous fingering (VF) in porous media has been investigated by using the standard over-relaxed Gauss-Seidel scheme. The simulation results show that the VF structure varies with the correlation parameter ε, the viscosity ratio M and the percolation probability P. The smaller the correlation parameter ε, the greater the deviation of the normalized size distribution of the invaded throat Ninv(r) from the truncated Rayleigh distribution. For a larger viscosity ratio M, the VF pattern looks like a diffusion-limited-aggregation structure in percolation clusters. The fractal dimension D increases with the increase of the percolation probability P and the correlation parameter ε. The velocity distribution f(α) of VF in percolation clusters is of a parabola-like curve. The tail of the distribution (large α) is longer for a larger correlation parameter ε. For a smaller ε, the distribution is very sharp. The sweep efficiency E decreases along with the decrease of the correlation parameter ε and the increase of the network size Lnz. E has a minimum as Lnz increases up to the maximum no matter what the values of P, M and ε. The E~ Lnz curve has a frozen zone and an active zone. The geometry and the topology of the porous media have strong effects on the displacement processes and the structure of VF.    

18.  Saturation of biphoton generation near atomic resonance  
   陈鹏  钱军  胡正峰  王育竹《中国物理 B》,2012年第11期
   We have numerically investigated the biphoton generation rate as a function of several parameters in the spontaneous four-wave mixing in cold atoms.It has been found that the biphoton generation rate can easily reach saturation with the intensity of the coupling laser increasing.The saturation intensity is mainly dependent on the dephasing rate of the ground states,unrelated to the pumping laser.It implies that though the biphoton waveform can be manipulated by the coupling laser,the generation rate of the biphoton cannot increase markedly after the saturation.The saturation effect also suggests that there is an optimal coupling laser for obtaining the largest biphoton generation rate with a sufficiently long coherence time.    

19.  Research on a novel compact linac  
   罗小为  相新蕾  谢家麟《中国物理 C》,2011年第35卷第1期
   This work looks at a new type of electron linear accelerator. Compared with the traditional electron linac, it has only two main parts: a klystron and an accelerating tube, without the electron gun element. This new kind of linac could perform just like its predecesors but reduce cost and space. The preliminary design and simulation have been accomplished. In this paper, an overview discussion about the performance tests and some improvements to increase the beam current are presented.    

20.  Weak-Coupling Theory for Semiclassical Periodically Driven Two-Level Systems: Beyond Rotating-Wave Approximation  
   YANG Xiao-Xue WU Ying《理论物理通讯》,2007年第47卷第2期
   In this paper,(2 1)-dimensional electron acoustic waves (EAW) in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique,respectively.The dispersion relation and a modified Kadomtsev-Petviashvili (KP) equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons.It is found from some numerical results that the parameter β (the ratio of the free hot electron temperature to the hot trapped electron temperature) effects on the amplitude and the width of the electron acoustic solitary waves (EASW).It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.    

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