Number Of Charged Particles Research Articles

Investigation on steering of ultrarelativistic e^{pm } beam through an axially oriented bent crystal

An investigation on stochastic deflection of high-energy charged particles in a bent crystal was carried out. In particular, we investigated the deflection efficiency under axial confinement of both positively and negatively charged particles as a function of the crystal orientation, the choice of the bending plane, and of the charge sign. Analytic estimations and numerical simulations were compared with dedicated experiments at the H4 secondary beam line of SPS North Area, with 120 GeV/c electrons and positrons. In the work presented in this article, the optimal orientations of the plane of bending of the crystal, which allow deflecting the largest number of charged particles using a bent crystal in axial orientation, were found.

Axion-radiation conversion by super and normal conductors

We have proposed a method for the detection of dark matter axion. It uses superconductor under strong magnetic field. As is well known, the dark matter axion induces oscillating electric field under magnetic field. The electric field is proportional to the magnetic field and makes charged particles oscillate in conductors. Then, radiations of electromagnetic fields are produced. Radiation flux depends on how large the electric field is induced and how large the number of charged particles is present in the conductors. We show that the electric field in superconductor is essentially identical to the one induced in vacuum. It is proportional to the magnetic field. It is only present in the surface because of Meissner effect. On the other hand, although the magnetic field can penetrate the normal conductor, the oscillating electric field is only present in the surface of the conductor because of the skin effect. The strength of the electric field induced in the surface is equal to the one in vacuum. We obtain the electric field in the superconductor by solving equations of electromagnetic fields coupled with axion and Cooper pair described by Ginzburg-Landau model. The electric field in the normal conductor is obtained by solving equations of electromagnetic fields in the conductor coupled with axion. We compare radiation flux from the cylindrical superconductor with that from the normal conductor with same size. We find that the radiation flux from the superconductor is a hundred times larger than the flux from the normal conductor. We also show that when we use superconducting resonant cavity, we obtain radiation energy generated in the cavity two times of the order of the magnitude larger than that in normal conducting resonant cavity.

Investigation into the event-activity dependence of \u03d2(nS) relative production in proton-proton collisions at sqrt{s} = 7 TeV

The ratios of the production cross sections between the excited ϒ(2S) and ϒ(3S) mesons and the ϒ(1S) ground state, detected via their decay into two muons, are studied as a function of the number of charged particles in the event. The data are from proton-proton collisions at sqrt{s} = 7 TeV, corresponding to an integrated luminosity of 4.8 fb−1, collected with the CMS detector at the LHC. Evidence of a decrease in these ratios as a function of the particle multiplicity is observed, more pronounced at low transverse momentum {p}_{mathrm{T}}^{upmu upmu} . For ϒ(nS) mesons with {p}_{mathrm{T}}^{upmu upmu} > 7 GeV, where most of the data were collected, the correlation with multiplicity is studied as a function of the underlying event transverse sphericity and the number of particles in a cone around the ϒ(nS) direction. The ratios are found to be multiplicity independent for jet-like events. The mean {p}_{mathrm{T}}^{upmu upmu} values for the ϒ(nS) states as a function of particle multiplicity are also measured and found to grow more steeply as their mass increases.

Studying the thinning Effect of Longitudinal development in Extensive Air Showers for Primary Proton and Iron Nuclei at Ultra-High Energies

In the present work, extensive air showers (EAS) effects are described by estimating the longitudinal development model of EAS at very high energies of various cosmic ray particles. The longitudinal development was simulated for charged particles such as gamma, charged pions and charged muons at very high energies 1017, 1018 and 1019eV. The simulation was performed using an air shower simulator system (AIRES) version 19.04.0. The effect of primary particles, energies, thinning energy and zenith angle (θ) on the number of charged particles (longitudinal development) produced in the EAS was taken into account. The rapprochement of the estimated longitudinal development of the charged particles such as the charged muons and charged pions with the experimental measurements (AUGER experiment) that gave a good agreement for primary proton at the fixed primary energy 1019eV for θ =0˚.

Measuring the depth of shower maximum of extensive air showers using Cherenkov light

A method is proposed to reconstruct the depth at which showers reach the maximum number of charged particles (Xmaxcharged) using atmospheric Cherenkov telescopes. The dependence of the Cherenkov signal with telescope distance from shower core is explored and a region in which the measurement is possible is determined (150 to 200 m). A parametrization is presented to reconstruct Xmaxcharged. The resolution of the method is studied as a function of energy, for different primary particle types and for telescope fields of view ranging from 3.5∘ to 10∘. Good resolution ( ∼ 25 g/cm2) is achieved for most of the cases of primary particle type (gamma ray, proton and iron nuclei) and energy (10 TeV < E < 300 TeV). Very good resolution ( < 15 g/cm2) is achieved in the best cases and not so good resolution ( > 40 g/cm2) is seen for energies below 30 TeV. The results presented here contribute to the understanding of the development of gamma-ray showers and suggest another possibility of using atmospheric Cherenkov telescopes to study cosmic rays in the TeV-PeV energy range.

The multiplicity characteristics of7Li-Em interactions as a function of noninteracting projectile nucleons

In this work, the interactions of7Li nuclei with emulsion at 3 A GeV/c were studied. Multiplicity of the charged secondary particles as well as the charge of the outgoing projectile fragments were measured, while correlations among them are discussed. The values of the total charge of the noninteracting projectile nucleons and the average number of interacting projectile nucleons are estimated. The dependence of the secondary particles on the number of heavily-ionized tracks is analyzed. The results show that interactions of7Li nuclei with emulsion nuclei exhibit a number of regularities, which had been noted in experiments with lighter nuclei. The absorption of relativistic particles, while increasing the degree of target destruction, is observed. The average multiplicities of the secondary charged particles depend on the impact parameter, as their values increase, while decreasing the impact parameter. The number of secondary charged particles in the heavy-ion interactions depends on the degree of disintegration of the target nuclei. This dependence is not observed in the case of the interaction of hadron with emulsion. The experimental data of the interaction of7Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

A Study of Pseudo-Central Collision Events Observed in Pion-Nucleus Interactions

The present study is based on the interactions caused by 340-GeV negative pions with emulsion nuclei. The main aim of this paper is to investigate some aspects of central collision events. Thus, the events in which the total number of charged shower particles is greater than or equal to twenty eight (Ns geq 28) were chosen for the analysis. They are not exactly central collision events, but may be considered as pseudo-central collision events. The angular characteristics of relativistic charged secondaries have been studied in terms of pseudo-rapidity, and bimodality is found to be absent in the distributions. The mean pseudo-rapidity seems to be independent of grey and heavy particle multiplicities, which indicates its independence with number of collisions. Finally, the correlation between different particle multiplicities in this paper is discussed.

The Effect of Field‐Aligned Currents and Centrifugal Forces on Ionospheric Outflow at Saturn

AbstractIonospheric outflow is driven by an ambipolar electric field induced due to the separation of electrons and ions in a gravitational field when equilibrium along a magnetic field line is lost. A model of ionospheric outflow at Saturn was developed using transport equations to estimate the number of charged particles that flow from the auroral regions into the magnetosphere. The model evaluates the outflow from 1,400 km in altitude above the 1 bar level, to 3 RS along the field line. The main ion constituents evaluated are R+ and . We consider the centrifugal force exerted on the particles due to a fast rotation rate, along with the effects of field‐aligned currents present in the auroral regions. The total number flux from both auroral regions is found to be 5.5–13.0×1027 s−1, which relates to a total mass source of 5.5–17.7 kg s−1. These values are on average an order of magnitude higher than expected without the additional effects of centrifugal force and field‐aligned currents. We find the ionospheric outflow rate to be comparable to the lower estimates of the mass loading rate from Enceladus and are in agreement with recent Cassini observations. This additional mass flux into the magnetosphere can substantially affect the dynamics and composition of the inner and middle magnetosphere of Saturn.

Ionization yield measurement using metal electrodes with a static electric field in ambient air

The amount of ionization produced in a laser-matter interaction provides critical information in studying strong field physics and attosecond science. The amount of ionization can be accurately measured in vacuum using a photoelectron/ion spectrometer by counting the number of charged particles. However, an ionization yield measurement in ambient air requires the considerations of post processes such as drift and recombination of charged particles, which may add an unwanted nonlinearity to the measurement. Here we investigate the kinetics of the charged particles after optical field ionization in ambient air under a static bias field. A simple kinetic model is used in which coupled rate equations are numerically solved. The kinetic model explains the recombination loss of the charged particles observed in ionization yield measurements. A condition for the static bias field is derived for an accurate ionization yield measurement.

Mechanical features and radiation shielding properties of TeO2–Ag2O-WO3 glasses

This work aimed to investigate the mechanical features and radiation shielding properties of (100–2x)TeO2+xAg2O + xWO3 (where x = 7.5, 15, 22.5, and 30 mol%) glass system. Based on Makishima–Mackenzie's theory, the basic mechanical features such as packing density, Poisson's ratio, elastic moduli, hardness, and fractal bond connectivity were studied. The shielding investigations included the radiations of gamma, electron, neutron, and heavy charged particles. Geant4 toolkit and newly developed Phy-X program were employed to evaluate mass attenuation coefficient (μ/ρ), transmission factors (HVL and MFP), exposure buildup factor (EBF) and effective atomic number (Zeff) of gamma and charged particles for the studied glasses. Neutron shielding investigation was examined by determining neutron removal cross section (NRCS) of the glasses involved. The results showed that Ag2O and WO3 contents had an insignificant effect on the mechanical properties of the investigated glass system. In contrast, the Ag2O and WO3 contents had a significant effect on the shielding capacity of the glasses against gamma radiation and charged particles. The Zeff values were in the range of 24–60 for gamma, 24–31 for electron, 18–24 for proton, 15–23 for alpha, and 13–19 for carbon ion. The shielding properties of these glasses were compared with those of commonly used shields. The investigated glass system can be used in shielding applications, wherein Ag2O and WO3 contents can be balanced with the TeO2 content according to the type and energy of the radiation.

Effect of Filling Rate on Underwater Wet Welding Process and Weld Appearance.

Real-time electric signal, matter transfer mode and welding pool behavior were obtained to investigate the effect of wires’ filling rate on arc stability and joints’ appearance during underwater wet flux-cored arc welding (FCAW). The electric signal results showed that arc stability first decreased and then increased rapidly because the raise of filling rate affected the number of charged particles and the electrical conductivity of welding arc atmosphere. Two typical transfer modes, globular repelled transfer mode and surface tension transfer mode, were observed in this study. The ratio of surface tension transition could be increased by adding wires’ filling rate. Meanwhile, the geometry of molten pool was changed and the distance between droplets to welding pool reduced as the filling rate increased. The fusion line became more regular and the radius of curvature increased under the effect of bubbles in the molten pool. As the filling rate improving, more slags on the welds surface were acquired and the welds were much flatter and smoother.

Performance study on a metal ion plasma thruster using a trumpet-shaped insulated anode with double micropores

A metal ion plasma thruster (MIPT) structure using a trumpet-shaped insulated anode with double micropores (TsIADM), which consists of a frustum-cone-shaped cathode, insulating sleeve, trumpet-shaped anode and anodic insulating layer with double micropores, is proposed. The differences in discharge characteristics and propulsion performance of the TsIADM-MIPT and two other structures, a trumpet-shaped semi-insulated anode MIPT and a conventional trumpet-shaped exposed anode (TsEA) MIPT, are compared and analyzed. Furthermore, the influence that the position of the double micropores has on the MIPT performance is discussed. The results show that the thrust and thrust-to-power ratio are all largest when the double micropores are set at the top end of the inner insulating layer of the trumpet-shaped anode (TsIADM(T)-MIPT). When compared with the TsEA-MIPT, the TsIADM(T)-MIPT demonstrates thrust and thrust-to-power ratios that are improved by 11.6 and 9.5 times respectively. The discharge parameters show that the number of charged particles flowing into the anode in a single shot decreases obviously when adopting the TsIADM(T). The discharge phenomena indicate that compared with the TsEA-MIPT, the luminescence intensity and ejection performance of the plasma plume using the TsIADM(T)-MIPT increases significantly. When the capacitor energy of the system is 5 J, Langmuir probe data show that the plasma density and plasma propagation speed are increased by 16.5 and 4.6 times respectively. These results are believed to be fundamental to the physical mechanisms behind the increased thrust and thruster-to-power ratio of the TsIADM(T)-MIPT.

Kinetic approach to the Schwinger effect during inflation

Using the kinetic approach, we study the impact of the charged particle dynamics due to the Schwinger effect on the electric field evolution during inflation. As a simple model of the electric field generation, we consider the kinetic coupling of the electromagnetic field to the inflaton via the term ${f}^{2}(\ensuremath{\phi}){F}_{\ensuremath{\mu}\ensuremath{\nu}}{F}^{\ensuremath{\mu}\ensuremath{\nu}}$ with the Ratra coupling function $f=\mathrm{exp}(\ensuremath{\beta}\ensuremath{\phi}/{M}_{p})$. The production of charged particles is taken into account in the Boltzmann kinetic equation through the Schwinger source term. Produced particles are thermalized due to collisions which we model by using the collision integral in the self-consistent relaxation time approximation. We found that the current of created particles exhibits a non-Markovian character and cannot be described by a simple Ohm's law relation $j\ensuremath{\propto}E$. On the contrary, the electric current as well as the electric field are oscillatory functions of time with decreasing amplitudes and a phase difference due to the ballistic motion of charged carriers. Our qualitative results are checked by using a hydrodynamic approach. Deriving a closed system of equations for the number, current, and energy densities of charged particles and determining its solution, we find a good agreement with the results obtained in the kinetic approach.

Measurement of flow harmonics correlations with mean transverse momentum in lead\u2013lead and proton\u2013lead collisions at\xa0sqrt{s_{mathrm{NN}}} = 5.02~hbox {TeV} with the ATLAS detector

To assess the properties of the quark–gluon plasma formed in ultrarelativistic ion collisions, the ATLAS experiment at the LHC measures a correlation between the mean transverse momentum and the flow harmonics. The analysis uses data samples of lead–lead and proton–lead collisions obtained at the centre-of-mass energy per nucleon pair of 5.02 TeV, corresponding to total integrated luminosities of 22~upmu text {b}^{-1} and 28~text {nb}^{-1}, respectively. The measurement is performed using a modified Pearson correlation coefficient with the charged-particle tracks on an event-by-event basis. The modified Pearson correlation coefficients for the 2nd-, 3rd-, and 4th-order flow harmonics are measured in the lead–lead collisions as a function of event centrality quantified as the number of charged particles or the number of nucleons participating in the collision. The measurements are performed for several intervals of the charged-particle transverse momentum. The correlation coefficients for all studied harmonics exhibit a strong centrality evolution, which only weakly depends on the charged-particle momentum range. In the proton–lead collisions, the modified Pearson correlation coefficient measured for the 2nd-order flow harmonics shows only weak centrality dependence. The lead-lead data is qualitatively described by the predictions based on the hydrodynamical model.

Study of ionic wind based on dielectric barrier discharge of carbon fiber spiral electrode

Based on the idea that a large number of charged particles can be generated by a high-frequency alternating current (AC) dielectric barrier discharge (DBD), and charged particles can be accelerated directionally by a direct current (DC) electric field, a new type of ionic wind formation method is proposed in this paper. To this end, a carbon fiber spiral electrode serves as the generation electrode and a metal rod electrode as the collection electrode, with AC and DC potentials applied respectively to the generation electrode and the collection electrode to form an AC–DC coupled electric field. Under the action of the coupled electric field, a dielectric barrier discharge is formed on the carbon fiber spiral electrode, and the electrons generated by the discharge move from the generation electrode to the collection electrode in the opposite direction of the electric field vectors. During the movement, energy is transferred to the gas molecules by their colliding with neutral gas molecules, thereby forming a directional gas stream movement, i.e. ionic wind. In the research process, it is verified through electric field simulation analysis and discharge experiment that this method can effectively increase the number of charged particles in the discharge process, and the velocity of the ionic wind is nearly doubled. On this basis, the addition of a third electrode forms a distinct discharge region and an electron acceleration region, which further increases its velocity. The experimental result shows that the ionic wind speed reaches up to 2.98 m s−1. Thanks to the ability of the electrode structure to generate an atmospheric pressure DBD plasma and form an ionic wind, we can create a noise-free air purification device without resorting to a fan, with this device having good application prospects in the field of air purification.

Case study on the influence of electrostatic charges on particle concentration in turbulent duct flows

Preferential concentration of inertial particles in wall-bounded turbulent flows is of paramount importance and, thus, subject of fundamental research. In practical applications of confined particle-laden flows the particles experience frequent collisions with the piping system which may result in an unwanted electric charge separation through triboelectric effects. The consequential occurrence of electrostatic forces alters the particle trajectories and their distribution. In this work the influence of charges on the averaged concentration of inertial particles in a fully developed turbulent duct flow was investigated by means of a combined numerical and experimental approach. The order of magnitude of the potential charge accumulation was estimated and imposed in a parametric study to the particulate phase in the simulations. Also, a new numerical approach based on the stochastic parcel method is introduced that allows to handle a large number of charged particles in a Lagrangian framework. This new approach extends standard formulations by including the effect of electrostatic forces on each parcel. The simulations demonstrate that the concentration profiles are for the most part independent of the prescribed charge except in the region close to the walls. The peaks of the particle number density at the walls caused by turbophoresis are strongly reduced through the local increase of repelling electrostatic forces. The comparison of numerical with experimental data indicates that the particles in the experimental setup could be affected by a surface charge density of the order of 100 C/m2. The presented results aim to elucidate the impact of electrostatic forces in the particle distribution in wall-bounded particle-laden flows.

ELECTRICAL CONDUCTIVITY AND SORPTION PROPERTIES OF THE COMPOSITES BASED ON ION EXCHANGE POLYMERS

The review is devoted to the conditions for the creation and functional properties of organіс-inorganic ion-exchange materials, which in the form of sorbents and membranes can be applied in the processes of ion separation, as well as the purification of water and combined solutions of technological origin. The structure of air dry and hydrated organic ion-exchange polymers, conditions for the creation of organiс-inorganic ion-exchange materials, as well as their components, interaction of components and the corresponding classification are considered. Dry ion-exchange materials contain heterogeneities of different sizes, which are formed during the synthesis of polymer, with the smallest heterogeneities represent clusters, and the larger ones are related to crystallinity. The structure of hydrated ion- exchange materials adequately describes the cluster channel model of Hsu and Girke. The number of charged particles transferred corresponds to the contribution of clusters and channels (volume fractions) to total porosity. The size of the clusters and channels can be determined by the method of small-angle X-ray scattering. The complex porous structure of ion-exchange polymers makes it possible to form inorganic particles in the one’s pores. The introduction of inorganic ion exchangers into the polymer leads to the appearance of additional osmotically active centers (fixed ions and antimony modifiers) that influence the compression pressure of composites. Regarding the functional properties of organiс-inorganic materials, data on the influence of the form and size of the nanoparticles of the inorganic component on the electrical conductivity of composites, examples of the use of organiс-inorganic sorbents in ion-exchange columns, and also effective diffusion coefficients corresponding to the exchange of two-charge metal cations (Zn2+, Pb2+, Cu2+, Ca2+, Ni2+) on H+ organic-inorganic sorbents, for the most part, organic resin- Dowex HCR-S with incorporated particles of zirconium hydrophosphate, are presented. The prospect of application of such materials in ion-exchange and membrane processes of separation and purification of aqueous solutions, as well as in the processes of efficient selective extraction of target ions, is shown.

Study of Time Evolution of the Bend-over Energy in the Energetic Particle Spectrum at a Parallel Shock

Abstract Shock acceleration is considered one of the most important mechanisms for the acceleration of astrophysical energetic particles. In this work, we calculate the trajectories of a large number of test charged particles accurately in a parallel shock with magnetic turbulence. We investigate the time evolution of the accelerated particle energy spectrum in the downstream of the shock, in order to understand the acceleration mechanism of energetic particles. From simulation results we obtain power-law energy spectra with a bend-over energy, E 0, increasing with time. With the particle mean acceleration time and mean momentum change during each cycle of the shock crossing from the diffusive shock acceleration model (following Drury), a time-dependent differential equation for the maximum energy, E acc, of particles accelerated at the shock can be approximately obtained. We assume the theoretical bend-over energy as E acc. It is found that the bend-over energy from simulations agrees well with the theoretical bend-over energy using the nonlinear diffusion theory, NLGCE-F, in contrast to that using the classic quasi-linear theory.

Some consequences of theories with maximal acceleration in laser–plasma acceleration

In this paper, we consider classical electrodynamic theories with maximal acceleration and some of their phenomenological consequences for laser–plasma acceleration. It is shown that in a recently proposed higher-order jet theory of electrodynamics, the maximal effective acceleration reachable by a consistent bunch of point-charged particles being accelerated by the wakefield is damped for bunches containing large number of charged particles. We argue that such a prediction of the theory is falsifiable. In the case of Born–Infeld kinematics, laser–plasma acceleration phenomenology provides an upper bound for the Born–Infeld parameter b. Improvements in the beam qualities will imply stronger constraints on b.

The spinful large charge sector of non-relativistic CFTs: from phonons to vortex crystals

We study operators in Schrödinger invariant field theories (non-relativistic conformal field theories or NRCFTs) with large charge (particle number) and spin. Via the state-operator correspondence for NRCFTs, such operators correspond to states of a superfluid in a harmonic trap with phonons or vortices. Using the effective field theory of the Goldstone mode, we compute the dimensions of operators to leading order in the angular momentum L and charge Q. We find a diverse set of scaling behaviors for NRCFTs in both d = 2 and d = 3 spatial dimensions. These results apply to theories with a superfluid phase, such as unitary fermions or critical anyon systems.