Pronounced Fluctuations of Target Fragments in Forward Hemisphere Only in Ultra Relativistic Nuclear Collision

Dynamical fluctuation of target evaporated black particles is investigated in both forward and backward hemispheres within the framework of multi-dimensional factorial moment methodology using the brilliant concept of the Hurst exponent. We analyse the black particles emitted in ^32S-AgBr interactions at 200AGeV and it is evident that the dynamical fluctuation in the backward hemisphere is self-affine. In the forward hemisphere, dynamical fluctuation is self-similar but not self-affine. However, study indicates that the fluctuation in the forward hemisphere is more pronounced than that in backward hemisphere.     

Production of Ring-like Events in pp Collisions at 400GeV/c

The production mechanism of ring-like events has been investigated by using the data of pseudorapidity distribution of charged particles produced in pp collisions at 400GeV/c. The results show that the model of coherent gluon emission within a finite region of space-time is a possible production mechanism of ring-like events, but certainly not dominant.     

400GeV/c pp碰撞类环事例的产生

利用400GeV/c pp碰撞产生的带电粒子赝快度分布的实验数据,研究了类环事例的产生机制.结果表明在一有限的时间-空间范围内相干胶子辐射是类环事例的一种可能的产生机制,但肯定不是主要的.     

Nuclear Fragments in the Interactions of Carbon Nuclei with a Beryllium Target at the Energy of 0.95 GeV per Nucleon

The differential cross sections for the yields of nuclear fragments at an angle of 3.5? in the fragmentation of carbon nuclei with energy 0.95 GeV per nucleon on a beryllium target were measured in the FRAGM experiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of fragments were used to test the following four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD. For light fragments, the slope parameters of the kinetic-energy spectra were obtained in the cumulative region.     

Resonances and Fluctuations in Nuclear Reaction Cross Sections

On the basis of the continuum shell model, an expression for the S-matrix is derived. The external mixing between shape resonances and resonance states of complicated nuclear structure is investigated. It is shown that the doorway properties of the shape resonances may lead to an l-dependent transparency of the optical potential and, consequently, to an energy dependence of large back angle scattering if the unitarity of the S-matrix is taken into account.     

Position-Sensitive Scintillation Detector of Nucleons and Nuclear Fragments

Physics of Particles and Nuclei Letters - A scintillator detector of neutrons and nuclear fragments has been designed, manufactured, and tested on a cosmic-ray stand. The scintillation light is...     

超高能核作用中的晕事例

观测能量大于10¹⁵eV的γ族事例,在乳胶室中往往形成晕,给进一步观测超高能核作用的特征带来许多不便.目前只能给出一些粗糙的量来描述晕事例.然而晕事例的内部还有精细的结构,能提供更多的信息.作者对超高能族事例尽可能作逐个簇射测量,并用测量晕的方法进行重复测量,进行比较.并就某些特例作了分析与讨论.     

高能诱导核反应中的核碰撞几何与末态粒子的间歇行为

考虑到核碰撞几何,我们推导出高能诱发核反应中二阶阶乘矩与参加反应核子数涨落之间的关系.分析表明,在高能碰撞的射弹碎裂区,强子-核反应末态粒子的间歇性质决定于其强子-强子子过程的间歇特征;而在靶碎裂区,它却主要依赖于参加反应核子数的涨落.推广到核-核反应(B<相似文献   

On the Emission of Target Black Fragments in High Energy Nucleus-Nucleus Collisions

The mechanism of friction-evaporation process for target spectator contact layer in high energy nucleus-nucleus collisions is presented.The distribution of multiplicity,azimuthal and spatial angles,transverse and total momenta,as well as kinetic energy of target black fragments are calculated and compared with the experimental results of 200GeV/N ¹⁶O-Em interactions.     

Structure of Magnetic Plasma Fluctuations in the Uragan-3M Torsatron at Rare Collision Frequencies

Technical Physics - Fluctuations of the poloidal component of the plasma magnetic field in the frequency range of 0.5–50 kHz are studied in the Uragan-3M (U-3M) torsatron. Hydrogen plasma is...     

Nuclear Matter Density,Collision Number and Entropy in Dynamics Process of Intermediate High Energy Heavy Ion Collision

The nuclear matter density,collision number and entropy in the dynamic process of heavy ion collision ⁴⁰Ca+⁴⁰Ca at E_L=400MeV/A for very central collision were calculated.The results show that the nuclear spatial density distributions depend mainly on the mean field but rarely on the nucleonnucleon collisions.The density distribution in the momentum space,collision number and entropy are influenced by the mean field and nucleon-nucleon collision,especially the medium effects.     

碰撞打靶实验中的能量损失及不确定度估算

对碰撞打靶实验中的能量损失,先作理论估算,再通过实验验证.讨论二者不一致时如何获得修正值以及测量值的显著性检验问题.还讨论了实验的不确定度估算问题.得出的结论是碰撞打靶实验过程中的能量损失大部分源于非弹性碰撞,其余主要来自空气阻力.     

Operator of Effective Permittivity of a Statistically Inhomogeneous Medium with Strong Fluctuations

The majority of known works on the theory of multiple scattering of electromagnetic waves in media with strong fluctuations are constrained by the assumption of statistical homogeneity of a medium. In this paper, we consider an isotropic lossy random medium, for which the principle value and multipole moments of the permittivity are invariant with respect to arbitrary rotations about a fixed symmetry axis and translations along the axis and are inhomogeneous in the radial direction. This paper is aimed at calculating the effective permittivity operator (EPO) for such a medium for the case of strong permittivity fluctuations.     

500 AMeV 56Fe诱发乳胶核反应弹核碎裂研究

通过利用日本放射线医学综合研究所( NIRS ) 重离子医用加速器( HIMAC) 产生的束流照射国产的核-4型原子核乳胶,对500 AMeV 56Fe诱发乳胶核反应粒子产生进行了研究。讨论了500 AMeV 56Fe诱发乳胶核反应弹核碎片的多重数分布,并与其他结果进行了比较。结果表明,弹核碎片平均多重数随靶核质量的增加而增加,与入射能量无关。A stack of domestic N-4 nuclear emulsion was exposed to 56Fe ions at 500 AMeV at the HIMAC of NIRS. Particle production was investigated in 56Fe-Em interactions. The multiplicity distribution of projectile fragments was given in this paper and compared with other experimental results of heavy ion induced nuclear reactions in nuclear emulsion. The results show that the multiplicity of projectile fragments increase with the increasing target mass, and thereis no dependence on the projectile energy.     

On K-Factor's Non-Constancy for the Drell-Yan Process in Carbon-Carbon Nuclear Collision

The double Q²-rescaling model is used to compute the change of K-factor with x_A2 when the nucleus carbon-nucleus carbon collision occurs at different values of x_Al, where x are momentum fraction variables. In the calculation, the contributions of annihilations and Compton scattering have been considered for the Drell-Yan process. The calculated results show that the plots of K-factor versus X_A2 are very different for different values of x_Al. They are also compared with experimental data, which provides a test to the model of nuclear effect and the QCD theory itself     

AGS能量下核系统的强阻止性

本文给出了一个简单的相对论性强子级联模型,并用它模拟了Si(14.6A GeV/c)+Au的反应.研究了共振态对质子π的快度分布以及质子横质量分布的影响.在此模型中,碰撞粒子的纵动量变化(非弹情形)由阻止律给出;而粒子的横动量分布通过指数分布或高斯分布抽样.我们的结果与E810(814)数据和E802的新结果较好地符合.这表明:共振态△的引入能更好地反映碰撞的物理过程;AGS能量下核系统的强阻止性已无可非议.     

Determining the Centrality of a Nuclear Collision Using a Hadron Calorimeter

Physics of Atomic Nuclei - Determining the centrality of a collision, or the impact parameter, in heavy-nucleus collisions is important for the analysis of all experimental data and their...     

重离子碰撞复合体系碎化产生超重核可能性的探讨

讨论了通过重核碰撞形成的复合体系破裂产生超重核的问题。评述了两种主要的理论模型:即早期发展的在碎化理论框架下的量子涨落理论和本课题组尝试发展的微观输运理论模型。概括阐述了微观输运理论研究^197Au＋^197Au,^238U＋^238U和^244Pu＋^244Pu等反应的主要结果,即反应中产生的超重碎块的几率与入射能的关系,复合体系和超重碎块的衰变机制以及所形成的超重碎块的结合能和形状的分布。In this paper, the possibility of producing superheavy fragments through composite system breaking up in massive nuclear reactions is investigated. Two main theoretical models, which are the quantum fluctuations with in the fragmentation theory developed at 1980＇s and improved quantum molecular dynamics model developed recently by our group, are briefly reviewed. The dependence of the production probability of superheavy fragments on the incident energy, the decay mechanism of composite system and superheavy fragments, and the distribution of binding energy of Superheavy fragments are discussed for reactions of ^244Pu＋^244Pu, ^238U＋^238U, 197Au＋^197Au based on the improved quantum molecular dynamics model.     

Impact of Strong Magnetic Fields on Collision Mechanism for Transport of Charged Particles

One of the main applications in plasma physics concerns the energy production through thermo-nuclear fusion. The controlled fusion is achieved by magnetic confinement i.e., the plasma is confined into a toroidal domain (tokamak) under the action of huge magnetic fields. Several models exist for describing the evolution of strongly magnetized plasmas, most of them by neglecting the collisions between particles. The subject matter of this paper is to investigate the effect of large magnetic fields with respect to a collision mechanism. We consider here linear collision Boltzmann operators and derive, by averaging with respect to the fast cyclotronic motion due to strong magnetic forces, their effective collision kernels.