中能重离子核反应同位素分布的统计模型计算

用统计擦去模型,引入新的介质中的核子一核子碰撞截面和核物质密度分布弥散度,对中能区由不同质量的重离子引起的核反应的同位素分布进行了研究,探讨了介质效应和核物质密度分布弥散度对同位素分布的影响.     

相对论重离子碰撞的温度涨落与热容

使用LUCIAE3.0模型模拟了SPS能区Pb+Pb和C+C在不同能量(E_lab=20—200A GeV)和不同中心度下的重离子碰撞.并通过逐个事件的粒子温度涨落提取出了相应粒子的热容,发现对于同一碰撞系统,单位发射粒子的热容随碰撞能量的升高而下降直至饱和,随着碰撞参数b的增大而减小,而且发现单位发射粒子的热容具有随粒子质量的变大而变大的关系.同时还发现不同碰撞系统中同一种粒子具有相同的单位发射粒子热容,并给出了相应的解释.     

Simulation of energy scan of pion interferometry in central Au＋Au collisions at relativistic energies

We present a systematic analysis of two-pion interferometry for the central Au＋Au collisions at √SNN=3, 5, 7, 11, 17, 27, 39, 62, 130 and 200 GeV/c with the help of a multiphase transport （AMPT） model. Emission source-size radius parameters Rlong, Rout, Rside and the chaotic parameter A are extracted and compared with the experimental data. Transverse momentum and azimuthal angle dependencies of the HBT radii are also discussed for central Au＋Au collisions at 200 GeV/c. The results show that the HBT radii in central collisions do not change much above 7 GeV/c. For central collisions at 200 GeV/c, the radii decrease with the increasing of transverse momentum PT but are not sensitive to the azimuthal angle. These results provide a theoretical reference for the energy scan program of the RHIC-STAR experiment.     

Isoscaling behavior studied by HIPSE model

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.     

奇异反超核和反物质

文章简要回顾了反物质研究历史,重点阐述了过去几年反物质研究领域的新结果,包括美国布鲁克海汶国家实验室的相对论重离子对撞机(RHIC)上观测到的首个反物质超核信号和迄今为止最重的反物质原子核——反氦4。同时,还介绍了欧洲核子中心(CERN)反氢原子捕捉的新结果以及宇宙空间站上α磁谱仪(AMS)二期的新进展等,并讨论了这些进展对认识物质结构的启示。     

超强激光与“霍金-安鲁辐射”实验研究进展综述

对利用激光进行霍金-安鲁辐射实验的研究现状和实验挑战点等方面进行综述。霍金-安鲁辐射是量子引力理论的重要推论之一。对其进行实验观测研究,将对量子引力理论、大统一理论、乃至万物终极理论的发展具有重要推动作用。霍金-安鲁辐射可以通过强激光、储存环、潘宁阱、声学、玻色-爱因斯坦凝聚等各种实验手段加以研究,其中借助强激光有两类方法:人工光学黑洞和强激光加速。前者是利用介质的非线性效应,产生一个光波传播的视界,进而对视界附近的量子现象,包括霍金-安鲁辐射,进行研究;后者是利用超强激光场对电子施加的超高加速度来研究电子的霍金-安鲁辐射等特性。     

中高能重离子碰撞中的电磁场效应和手征反常现象

重离子碰撞可以产生极强的电磁场和高温高密量子色动力学(QCD)物质,诱导很多重要手征反常现象,例如手征磁效应和手征磁波.本文围绕手征反常现象中的诸多物理要素,详细介绍包括相对论重离子碰撞中不同碰撞系统和能量下的电磁场特性、同质异位素碰撞中寻找手征磁效应、手征磁波特性、中低能重离子碰撞中磁场效应等一系列与电磁场和手征反常现象相关的理论研究成果.相关研究有助于实验中寻找强相互作用中的电荷宇称(CP)破缺的证据,加深对QCD真空涨落和宇宙中正反物质不对称问题的理解.     

Proton Halo or Skin in the Excited States of Light Nuclei

Properties of nuclei 13,15,N and 9B are investigated in the relativistic mean-field theory with NLz and NL3 force parameters.The calculated binding energies are very close to the experimental ones.The calculations show that the first excited state (1p1/2) in 9B,the first excited state (2s1/2)in 13 N and the second excited state(2s1/2) in 15N are weakly bound .In particular,for 13N and 15N,the proton density distributions in the two above excited states have a long tail and the rms radii of the last proton are greatly larger compared with their respective matter radii.It is predicted that a proton halo exists in the first excited state of 13N and in the second excited state of 15N,respectively.It also indicates that the first excited state in 9B is a proton skin state.     

Density effect of the neutron halo nucleus induced reactions in intermediate energy heavy ion collisions

Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the 15C induced reactions from 30-120 MeV/nucleon systematically. Here the valence neutron of 15C is assigned at both 1d5/2 and 2s1/2 states respectively in order to study the density effect of reaction mechanism. It is believed that the existent neutron halo structure at the 2s1/2 state of 15C will affect the light particle emission evidently. In our calculation, the different density distributions of 15C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons’ kinetic energy spectrum are sensitive to the initial density distribution.