Density Distribution Of Charged Particles Research Articles

Maximum Charged Particle Density Fluctuations in Relativistic Heavy-Ion Collisions

Correlation and clusterization amongst relativistic charged particles produced in 4.5 A and 14.5 A GeV/c 28 Si–nucleus collisions are investigated by examining the maximum fluctuations in the density of relativistic charged particles in narrow pseudorapidity-bins, Δη, in the Monte Carlo background. For a fixed Δη, the maximum charged particle density decreases exponentially with increasing value of total pseudorapidity and increases with increasing particle multiplicity. These features are, however, observed to be essentially independent of the beam energy and target size. Furthermore, the maximum charged particle density distribution in a narrow pseudorapidity interval indicates the existence of dynamical correlation and clusterization. A comparison of the findings of the present study with those reported by UA5, NA22 Collaborations and other groups permits us to draw some interesting and useful conclusions.

Asymptotic theory of spherical electrostatic probes in large Debye length plasmas containing negative ions

The problem of a spherical electrostatic probe in negative ion containing oxygen plasmas is treated by the matching asymptotic expansions technique [A. H. Nayfeh, Perturbation Methods (Wiley, New York, 1973)]. Assuming that the energy relaxation length is much smaller than the local characteristic length, explicit results are obtained in the asymptotic limits, (rp/rD)2≪1,(rp/rS)2≪1, where rD is the Debye radius, rS is the recombination length and rp is the probe radius. The perturbation region divides naturally into a thin space charged sheath, a transitional sheath, and a quasineutral chemically equilibrium plasma. The potential and charged particle density distributions are obtained. The calculated probe characteristic is presented in an analytical form.

Charged particle density distributions in Au induced interactions with emulsion nuclei at 10.7 A GeV

Charged particle pseudorapidity density distributions in Au induced reactions in nuclear emulsion at 10.7 A GeV have been measured. In peripheral events the shower particle distribution exhibits a two peak structure while in central collisions it has a Gaussian shape. The spectator protons appear in the second peak in the pseudorapidity spectra and exhibits a broader momentum distribution than expected from Fermi motion. The produced particle yield in central collisions is not substantially different from phenomenological descriptions based on data from O and S induced reactions.

A difference scheme for solving the initial value problem for one-dimensional Vlasov equations

A difference scheme is constructed for solving the initial value problem for one-dimensional Vlasov equations. The scheme is shown to be stable, and to converge to the solution of the continuous problem. It is used to solve a model problem concerning the charged-particle density distribution along the axis of a linear accelerator.

Impact induced plasma during a cometary fly-by

GIOTTO, the probe which is presently developed by the European Space Agency, will encounter comet Halley in March 1986 with a relative velocity of 69 km/s. The fore section of the surface will be submitted to the bombardment of dust grains and neutral molecules in the final phase of the mission, like that of an Earth orbiter during atmospheric re-entry. These particles have a kinetic energy of 24 eV per a.m.u.; they produce secondary ions and electrons which form a plasma cloud around the body and control the electric potential of its surface. This paper is a review of the work which has been performed on the subject by dedicated study groups; the purpose of their action was to gather information and produce new findings which might have an influence on the design of the spacecraft and help in the interpretation of the data collected by the scientific payload. The effect of impact induced plasma may already be significant at 10 5 km from the comet nucleus; at a distance of 1000 km the flux of ions and electrons produced by cometary dust and neutrals will possibly exceed that of the ambient plasma by more than three orders of magnitude. It is expected that the spacecraft surface potential will be positive and will reach at least a few tens of volts; coating the leading surface of the spacecraft with a thin layer of gold or silver will help reducing the emission of ions from neutral gas. Computer simulation models are used to predict the structure of the charged particle density distribution in the vicinity of the surface. Effects associated with the wake and differential charging are also discussed. The significance of these results is conditioned by the validity of the models and the largest source of uncertainty seems to be associated with the plasma generated by dust impact.

Interaction between a body and its environment during a cometary fly-by

The surface of a spacecraft is submitted to the bombardment of dust grains and neutral molecules during an atmospheric re-entry or a cometary fly-by. These particles create secondary ions and electrons which form a plasma cloud around the body and control the electric potential of its surface. Computer simulation models are used to predict the structure and dynamic behaviour of the charged particle density distribution for the cases of planar and cylindrical bodies. It is found that an ion and an electron layer form in the vicinity of the surface at distances of the order of the ion and electron Debye lengths, respectively. The potential of the surface is positive on the average and is a function of the electron mean kinetic energy. A positive potential barrier develops at the location of the ion layer and its height is governed by the sum of the electron and ion mean kinetic energies. The threat caused by this interaction to the spacecraft and its instrumentation is discussed and an in-situ observation of this phenomenon is proposed as a possible diagnostic technique of the environment.

Radial density distribution of charged particles in an electronegative discharge plasma with space charges

The radial distribution of the electrons, as well as the positive and negative ions, respectively, has been determined theoretically in the positive column of the low-pressure discharge in an electronegative gas. The problem has been solved using a system of hydrodynamic equations and Poisson’s equation. This latter equation must be considered because of the volume recombination of the negative and positive ions and because of the space charges produced in the positive column. The method has been applied to the special case of the conical equipotentials often occuring in electronegative gases.

Flash tube hodoscopes for particle density measurements

Details on the construction and the performance characteristics of a 31 m 2 neon hodoscope are presented. The detector is in operation at Kiel since 1965 investigating the density distribution of charged particles in the cores of extensive air showers. It is shown that a device of this type meets most of the requirements for a large area detector in cosmic ray work.

Study of extensive air showers at Mount Norikura. I. Measurement of lateral structure

The lateral density distribution of charged particles in EAS is one of the essential parameters for the analysis of individual EAS. To measure the lateral density distribution in detail, 100 ¼-m2 scintillators were arranged in a lattice configuration with a unit distance of 5 m or 2.5 m. The conventional EAS array of 20 scintillators was also used to obtain densities up to about 100 m from the center. These observations are much more accurate than those obtained previously, and it has been found that there are various types of structure functions which can be approximated by the functions for single cascades of age parameter from 0.6 to 1.6. It was difficult in some instances to fit the lateral distribution by a unique function, especially for small EAS.The two-dimensional map obtained by means of the above 100 detectors shows that individual EAS have rarely a complicated structure within a range of about 20 m from the axis. The results are discussed in relation to the character of high-energy interactions as well as to fluctuations in the development of EAS.

Study of extensive air showers at Mount Norikura. III. Core structure and high-energy events

An area of 3 × 4 m2 is covered by 48 plastic scintillators above and below a water tank 2 m in depth. From maps of the charged-particle density and the energy-flow density in the core region, properties of EAS cores and of the high-energy nucleon component have been studied. About 25% of observed cores show the complicated structure of a "multiple core". These can be understood as due to effects of high-energy nuclear particles having large transverse momenta of several GeV/c to a few tens of GeV/c. The frequency of occurrence of such events increases with the size of EAS only slowly, but it decreases rapidly with increasing distance between the main cores and subcores. There is no clear distinction in the average lateral density distribution of charged particles between these multiple-core EAS and ordinary EAS at points distant from the cores.Comparing the particle density in both layers of detectors (top and bottom), the activity of cores has been studied. This fluctuates more than would be expected from the lateral structure of the showers.

Potential and density distribution of charged particles in a discharge plasma with oscillating electrons: L V Brzhechko and O S Pavlichenko,Zh Tekh Fiz, 37 (8), Aug 1967, 1508–1513 ( in Russian).

Potential and density distribution of charged particles in a discharge plasma with oscillating electrons: L V Brzhechko and O S Pavlichenko,Zh Tekh Fiz, 37 (8), Aug 1967, 1508–1513 ( in Russian).

Charged particle density distribution in a coaxial plasma gun

Upon measuring the magnetic field distribution and axial-electric field in a coaxial plasma gun, we could obtain the charged particles density distribution in the gun.

On the Diffusion Theory of the FARADAY Dark Space

AbstractWe calculate the charged particle density distribution in the Faraday dark space on the basis of a production free diffusion model. The solution of this problem determines the number density at the edge of the glow and produces a criterion for the extension of the Faraday dark space as a function of the current and pressure.

Lateral Density Distribution of Charged Particles in the Central Region of Extensive Air Shower

The lateral density distribution of the ionizing particles around the core of the extensive air shower has been observed with ten plastic scintillation counters at mountain altitude (2775 meters above sea level). The lateral density distribution, which has seemed so far to be expressed by the unique function of the distance from the central axis of extensive air showers, has been clearized as that it could be expressed by 1/ r n approximately is a range of 20 meters from the axis and n varies from 0.8 to 2.0 by the character of each shower. The result seems to have a relation to the fluctuation which has been presented in the previous paper or to the fluctuation of nuclear cascade in the development of extensive air showers. The density spectrum at single counter has been also analysed and the result supports above conclusion.