Nuclear shadowing and antishadowing in a unitarized BFKL equation

The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation.The Q2-and x-variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution.In particular,the asymptotical behavior of the unintegrated gluon distribution near the saturation limit in nuclear targets is studied. Our results in the nuclear targets are insensitive to the input distributions if the parameters are fixed by the data of a flee proton.     

Nuclear shadowing and antishadowing in a unitarized BFKL equation

The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation. The Q²- and x-variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution. In particular, the asymptotical behavior of the unintegrated gluon distribution near the saturation limit in nuclear targets is studied. Our results in the nuclear targets are insensitive to the input distributions if the parameters are fixed by the data of a free proton.     

Distribution angulaire des électrons secondaires émis par des monocristaux de cuivre sous bombardement ionique

Energy angular distributions of the secondary electronic emission from copper single crystals bombarded by 40 keV Ar⁺ ions are studied. These distributions, recorded as a function of the reception azimuth angle, with fixed polar angle, show an anisotropy which is both characteristic of the target cristalline structure and of the collected electron energy. We interpret these result in terms of bulk electron diffraction.     

Heavy quarks in polarized structure functions

Quark mass effects are included in the calculation of polarized structure functions. In particular, the validity of fixed order perturbation theory and of massless evolution is studied in the framework of heavy quarks structure functions. The polarized version of the ACOT and MRRS interpolating schemes for the evolution of massive quarks distributions is also developed and studied. The different behaviours of the various approaches in x and Q² are shown.     

以小区域内的离子数为控制信息实现束晕的有效控制

利用匹配半径外的某些固定区域内的离子数目提供控制信息,采用对数函数控制器对强流离子束进行束晕－混沌控制的数值模拟研究. 结果显示,该方法能够有效地抑制五种不同初始分布的离子束的束晕再生现象. 该方法由于控制信息的探测区域小且能固定,在实验上便于实施. 关键词： 束晕 控制 局部区域 信息     

On the linear chain with arbitrary masses and force constants. II. Ergodic properties

The ergodic properties of linear and quadratic phase functions of the classical linear chain are studied for the uniform statistical distributions on the energy surface and in the manifold belonging to fixed values of the energy and the total momentum. This is done for the finite chain by using the time dependent correlation functions studied in a previous paper¹). The thermodynamic limit is also discussed. As an example, sufficient conditions on the masses and force constants are given to ensure that the kinetic energy of a certain particle remains nonergodic in the thermodynamic limit, the conditions defining a non-exceptional set of chains.     

Two-particle Pseudorapidity Correlations in pp Collisions at 400GeV/c

The pseudorapidity distributions of charged produced in pp collisions at 400GeV/c have been measured using LEBC films.Two-particle pseudorapidity correlations at fixed multiplicity have been studied.The experimental data was fitted by cluster model.It is found that the average cluster multiplicities as well as the cluster decay widths both vary slightly with charged multiplicity.     

On hydromagnetic turbulent shear flow between moving parallel planes

Hydromagnetic turbulent shear flow of viscous, incompressible, electrically conducting fluid between two infinite uniformly porous moving parallel planes in the presence of axial and transverse magnetic field has been studied by the semi-empirical method. The expressions for the mean distributions for velocity and magnetic field for turbulent shear flow have been obtained for both the cases. As particular cases, the results have been obtained if the planes are fixed. The solutions obtained when the magnetic field is axial have been shown graphically for turbulent and laminar flows.     

颗粒速度在颗粒流稀疏流-密集流转变中的作用

用实验和计算模拟的方法研究了颗粒流中的颗粒速度与颗粒流特性的关系.实验研究发现当入口流量固定时，在出口上方高速运动的颗粒会使颗粒流由稀疏流向密集流转变的临界出口尺寸变小.当颗粒流转变为密集流后，颗粒速度的作用被出口上方的颗粒堆积区所消耗，最终变得与颗粒速度无关.二维分子动力学模拟计算得到了与实验相同的结论.通过二维分子动力学模拟计算，还给出了不同颗粒速度下体系的密度和速率在空间的分布图.这些分布图显示随着颗粒到达出口上方的瞬间速度的不同，颗粒堆积区的密度和高度均会改变，并最终导致颗粒流流动状态的改变. 关键词： 颗粒流 颗粒气体 分子动力学模拟     

Masses for clans introduced to explain hadronic multiplicity distributions

The facts that the negative binomial distribution very well describes high energy multiplicity distributions and that this distribution is the result of a compound Poisson-logarithmic distribution are used to search for new dynamics in particle production. It is shown that the logarithmic distribution for the particle multiplicity of clans follows if 1) the number of particles in the clans follows a Poisson distribution at fixed mass and 2) the mass distribution belongs to a certain class of distributions. Data are used to set limits on possible mass distributions. Comparisons with data are made for two examples of distributions.     

Viewing the proton through "color" filters

While the form factors and parton distributions provide separately the shape of the proton in coordinate and momentum spaces, a more powerful imaging of the proton structure can be obtained through phase-space distributions. Here we introduce the Wigner-type quark and gluon distributions which depict a full-3D proton at every fixed light-cone momentum, like what is seen through momentum ("color") filters. After appropriate phase-space reductions, the Wigner distributions are related to the generalized parton distributions (GPDs) and transverse-momentum dependent parton distributions, which are measurable in high-energy experiments. The new interpretation of GPDs provides a classical way to visualize the orbital motion of the quarks, which is known to be the key to the spin and magnetic moment of the proton.     

脉冲放电脱硫反应器中高能电子密度分布的光谱研究

脉冲流光放电产生的大于等于11.2 eV的高能电子能将处于基态的氮分子激发到N₂(C3Π_u)态,测试脉冲流光放电时的N₂(C3Π_u→B3Πg)发射光谱相对强度可以得出脉冲流光放电产生的高能电子的密度。实验在室温常压下研究了空气中线-板式脉冲流光放电脱硫反应器内高能电子密度分布情况,并研究了脉冲电压、反应器的线线间距对反应器内高能电子密度分布的影响。实验结果表明,反应器内的高能电子主要集中在放电线附近高电场区内,随着离放电线的距离增大,高能电子密度减小;脉冲电压对高能电子密度有很大影响,随着电压的升高,高能电子密度基本呈线性增大;线板间距固定,线线间距为线板间距的0.6～1倍时,反应器内高能电子密度分布较为均匀。     

Diffraction of X-ray spatially inhomogeneous beam in a crystal with cubic nonlinearity

Diffraction of a spatially inhomogeneous X-ray wave was theoretically studied in a crystal with cubic nonlinear response to the strength of an external electric field. Using numerical calculations in case of two-beam diffraction of a narrow incident beam, the intensity distributions on the output surface of the crystal was investigated depending on the thickness and intensity of the incident beam. The results of numerical calculations of integral (spatial) coefficients of transmission and reflection are given as functions of incident wave intensity for fixed thickness of the crystal.     

Strong field electron emission from fixed in space H(2)(+) ions

We have studied electron emission from the H(2)(+) ion by a circularly polarized laser pulse (800 nm, 6×10(14) W/cm(2)). The electron momentum distribution in the body fixed frame of the molecule is experimentally obtained by a coincident detection of electrons and protons. The data are compared to a solution of the time-dependent Schr?dinger equation in two dimensions. We find radial and angular distributions which are at odds with the quasistatic enhanced ionization model. The unexpected momentum distribution is traced back to a complex laser-driven electron dynamics inside the molecule influencing the instant of ionization and the initial momentum of the electron.     

Electron and phonon temperature fields in bounded semiconductors in a magnetic field

The electron and phonon temperature distributions in a semiconductor sample with finite dimensions, placed in a thermostat with an arbitrary, fixed temperature profile, were studied. Heat transfer between the thermostat and the electrons and phonons through the wall is assumed to be arbitrary, while the magnetic field is assumed to be weak.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 73–78, August, 1987.     

Effects of relativistic kinematics in heavy ion elastic scattering

Relativistic corrections to the reaction kinematic parameters were made for elastic scattering of ⁶Li, ¹²C and ⁴⁰Ar from ⁴⁰Ca, ⁹⁰Zr and ²⁰⁸Pb targets at incident energies between 20 and 100 MeV/nucleon. The results of optical model calculations show that the effects of such corrections are important when describing the angular distributions of elastic scattering cross sections for heavy ion scattering at incident energies as low as around 40 MeV/nucleon. The effects on the total reaction cross sections on the other hand, were found to be small within the energy range studied when the optical model potential is fixed.     

Equivalence of integral equations in the molecular theory of fluids

It is proven that, under physically reasonable conditions, the correlation functions satisfying the BBGKY equations for an infinite system are also solutions of the Mayer-Montroll and Kirkwood-Salsburg equations. The relation between these correlation functions and the probability distributions for finding a fixed number of particles in a given finite region of an infinite system is investigated. The Gibbsian nature of these probability distributions is shown to depend on the range of the intermolecular forces.     

Optimal Heat Exchanger Area Distribution and Low-Temperature Heat Sink Temperature for Power Optimization of an Endoreversible Space Carnot Cycle

Using finite-time thermodynamics, a model of an endoreversible Carnot cycle for a space power plant is established in this paper. The expressions of the cycle power output and thermal efficiency are derived. Using numerical calculations and taking the cycle power output as the optimization objective, the surface area distributions of three heat exchangers are optimized, and the maximum power output is obtained when the total heat transfer area of the three heat exchangers of the whole plant is fixed. Furthermore, the double-maximum power output is obtained by optimizing the temperature of a low-temperature heat sink. Finally, the influences of fixed plant parameters on the maximum power output performance are analyzed. The results show that there is an optimal temperature of the low-temperature heat sink and a couple of optimal area distributions that allow one to obtain the double-maximum power output. The results obtained have some guidelines for the design and optimization of actual space power plants.     

Soot particle size distributions in a well-stirred reactor/plug flow reactor

A well-stirred reactor (WSR) followed by a plug flow reactor (PFR) is being used to study polycyclic aromatic hydrocarbon (PAH) growth and soot inception. Soot size distributions were measured using a dilution probe followed by a nano-differential mobility analyzer (Nano-DMA). A rapid insertion probe was fabricated to thermophoretically collect particles from the reactor for transmission electron microscopy (TEM) imaging. Results are presented on the effect of equivalence ratio on the soot size distributions obtained for fixed dilution ratio, the effect of dilution ratio on the soot size distributions obtained for fixed equivalence ratio, and the effect of temperature on the soot size distributions obtained for fixed equivalence ratio. In addition to particle sizing measurements, gas samples were analyzed by a gas chromatograph to determine the concentration of gaseous species in the PFR thought to be important in soot formation. Our soot size distribution measurements demonstrate that the mixing conditions in the flame zone affect whether or not a nucleation mode was detected in the size distribution.     

高能核-核碰撞中粒子的(赝)快度分布与重叠柱模型

应用重叠柱模型描述了高能核-核碰撞中带电粒子的快度(或赝快度)分布. 对目前加速器上的固定靶实验而言, 观察到了相同相对强度的纵向流, 两个完全重叠的热化柱能够描述实验数据. 在更高能量范围(4A TeV以上), 观察到了更强的纵向流, 这时需要两个部分重叠的热化柱来描述实验数据. 用重叠柱模型计算得到的(赝)快度分布与1A GeV到100A TeV能区的实验结果符合.