Relativistic Charged Particles Research Articles

CoSyR: A novel beam dynamics code for the modeling of synchrotron radiation effects

The self-consistent nonlinear dynamics of a relativistic charged particle beam interacting with its complete self-fields is a fundamental problem underpinning many of the accelerator design issues in high brightness beam applications, as well as the development of advanced accelerators. Particularly, synchrotron radiation induced effects in a magnetic dispersive beamline element can lead to collective beam instabilities and emittance growth. A novel beam dynamics code is developed based on a Lagrangian method for the calculation of the particles’ radiation near-fields using wavefront/wavelet meshes via the Green’s function of the Maxwell equations. These fields are then interpolated onto a moving mesh for dynamic update of the beam. This method allows radiation co-propagation and self-consistent interaction with the beam in 2D/3D simulations at greatly reduced numerical errors. Multiple levels of parallelisms are inherent in this method and implemented in our code CoSyR to enable at-scale simulations of nonlinear beam dynamics on modern computing platforms using MPI, multi-threading, and GPUs. The current 2D implementation of CoSyR has been used to evaluate the transverse and longitudinal coherent radiation effects on the beam and to investigate beam optics designs proposed for mitigation of beam brightness degradation in a magnetic bunch compressor. In this paper, the design of CoSyR, as well as the benchmark with other coherent synchrotron radiation models, are described and discussed. Extension of the core algorithms to 3D is possible and planned.

Gauge dependence of spontaneous radiation spectrum in a time-dependent relativistic non-perturbative Coulomb field

We extend the "gauge choice" problem Lamb noticed to include a time-dependent relativistic non-perturbative Coulomb field, which can be produced by a cluster of relativistic charged particles. If adiabatic conditions are carefully maintained, such a field must be included along side the nuclear Coulomb potential when defining the atomic state. We reveal that when taking the external field approximation, the gauge choice for this time-dependent relativistic non-perturbative Coulomb field cannot be overcome by previous method, and leads to considerable gauge-dependence of the transient spontaneous radiation spectrum. We calculate explicitly with a simple one-dimensional charged harmonic oscillator that such a gauge-dependence can be of a measurable magnitude of 10 MHz or larger for the commonly used Coulomb, Lorentz, and multipolar gauges. Contrary to the popular view, we explain that this gauge dependence is not really a disaster, but actually an advantage here: The relativistic bound-state problem is so complicated that a fully quantum-field method is still lacking, thus the external field approximation cannot be derived and hence not guaranteed. However, by fitting to the experimental data, one may always define an effective external field, which may likely be parameterized with the gauge potential in a particular gauge. This effective external field would not only be of phenomenological use, but also shed light on the physical significance of the gauge field.

Relativistic Particle Transport and Acceleration in Structured Plasma Turbulence

Abstract We discuss the phenomenon of energization of relativistic charged particles in three-dimensional incompressible MHD turbulence and the diffusive properties of the motion of the same particles. We show that the random electric field induced by turbulent plasma motion leads test particles moving in a simulated box to be accelerated in a stochastic way, a second-order Fermi process. A small fraction of these particles happen to be trapped in large-scale structures, most likely formed due to the interaction of islands in the turbulence. Such particles get accelerated exponentially, provided their pitch angle satisfies some conditions. We discuss at length the characterization of the accelerating structure and the physical processes responsible for rapid acceleration. We also comment on the applicability of the results to realistic astrophysical turbulence.

Acceleration of a charged particle in the Redmond field

The motion of a relativistic charged particle in an external specified field of a planer single- and multifrequency circularly polarized electromagnetic wave of large amplitude in the presence of a constant uniform magnetic field (the Redmond field and the multifrequency Redmond field) when the relativistic consideration is required has been analyzed in detail. It is shown that the kinetic energy of a particle in the multi-frequency Redmond field depends not only on the intensity of the wave, and the frequencies of the carrier wave, but also on the direction of polarization of the wave (i.e., right- or left-handed), and the cyclotron frequency. The conditions required for autoresonant motion of a particle in an external field of a large-amplitude wave and the containment of a charged particle are considered.

On angular features of axial channeling radiation in crystals

Channeling of light relativistic particles in crystals is accompanied by intense radiation emission known as channeling radiation. Typically all calculations of channeling radiation aim in getting the total radiation intensity and its dependence on the parameters of particles and crystals. In the same time, since the discovery, the angular behaviours of channeling radiation have been studied just in a few works, in which only a polar dependence of the radiation intensity near the forward direction is estimated. However, simple analysis of the interaction potential predicts very specific features to be observed in the angular distributions of channeling radiation, especially at axial regime. In this work, for the first time, the expressions for angular and spectral distributions of electromagnetic radiation at axial channeling of relativistic charged particles in thin crystals are analytically refined within the QED theory. Obtained results allows predicting complex structures of radiation intensity and polarisation distributions. The results obtained might be of special interests for experimental studies.

On the interaction of a Cornell-type nonminimal coupling with the scalar field under the background of topological defects

In this paper, we investigate the influence of the background of a cosmic string space–time with a distortion of a radial line into a spiral on the interaction of the scalar field with a Cornell-type nonminimal coupling subject to a special static scalar potential. The special static scalar potential consists of radial oscillator harmonics potential and radial inverse-square potential. In order to study such a system based on the Katanaev–Volovich geometric approach, we acquire relativistic solutions corresponding to the generalized Klein–Gordon quantum oscillator for relativistic charged spin-zero boson particles using analytical methods in this background.

Generation of plasma electron halo by a charged particle beam in a low density plasma

Breaking of a plasma wave driven by a long beam of charged particles results in electron jets escaping from the plasma column and forming an electron halo. The halo is accompanied by a strong radial electric field around the plasma, which can distort the trajectories of relativistic charged particles that propagate near the plasma border or are injected into the plasma wave. We study the mechanisms of wave breaking and halo formation when the beam and plasma densities are comparable. If the plasma density is less than or of the order of the beam density, the wavebreaking is well described by a semi-analytical model, which agrees with simulations and allows us to calculate the position of wavebreaking points and determine the regions around the plasma column occupied by the halo.

Weak Turbulence and Quasilinear Diffusion for Relativistic Wave-Particle Interactions Via a Markov Approach

We derive weak turbulence and quasilinear models for relativistic charged particle dynamics in pitch-angle and energy space, due to interactions with electromagnetic waves propagating (anti-)parallel to a uniform background magnetic field. We use a Markovian approach that starts from the consideration of single particle motion in a prescribed electromagnetic field. This Markovian approach has a number of benefits, including: 1) the evident self-consistent relationship between a more general weak turbulence theory and the standard resonant diffusion quasilinear theory (as is commonly used in e.g. radiation belt and solar wind modeling); 2) the general nature of the Fokker-Planck equation that can be derived without any prior assumptions regarding its form; 3) the clear dependence of the form of the Fokker-Planck equation and the transport coefficients on given specific timescales. The quasilinear diffusion coefficients that we derive are not new in and of themselves, but this concise derivation and discussion of the weak turbulence and quasilinear theories using the Markovian framework is physically very instructive. The results presented herein form fundamental groundwork for future studies that consider phenomena for which some of the assumptions made in this manuscript may be relaxed.

Geant4 simulation of X-ray transition radiation at small angles

An algorithm for the angular distribution of X-ray transition radiation generated by a relativistic charged particle in regular radiators at small angles (less than 1 mrad) is discussed in the framework of the Geant4simulation toolkit. The model predictions are compared with experimental data recently obtained at the ATLAS TRT test beam.

Magnetic Field Amplification by a Plasma Cavitation Instability in Relativistic Shock Precursors

Abstract Plasma streaming instabilities play an important role in magnetic field amplification and particle acceleration in relativistic shocks and their environments. However, in the far shock precursor region where accelerated particles constitute a highly relativistic and dilute beam, streaming instabilities typically become inefficient and operate at very small scales when compared to the gyroradii of the beam particles. We report on a plasma cavitation instability that is driven by dilute relativistic beams and can increase both the magnetic field strength and coherence scale by orders of magnitude to reach near-equipartition values with the beam energy density. This instability grows after the development of the Weibel instability and is associated with the asymmetric response of background leptons and ions to the beam current. The resulting net inductive electric field drives a strong energy asymmetry between positively and negatively charged beam species. Large-scale particle-in-cell simulations are used to verify analytical predictions for the growth and saturation level of the instability and indicate that it is robust over a wide range of conditions, including those associated with pair-loaded plasmas. These results can have important implications for the magnetization and structure of shocks in gamma-ray bursts, and more generally for magnetic field amplification and asymmetric scattering of relativistic charged particles in plasma astrophysical environments.

Спектрально-угловые характеристики излучения заряженной частицы в поле Редмонда

Based on the solution of the equation of motion of a charge in an electromagnetic field, the classical theory of radiation of a relativistic charged particle linearly accelerated by a high-intensity laser pulse in the presence of a static component of the magnetic field is constructed. Solutions obtained by Kopytov G.F. and Pogorelov A.V., were used to study the spectral-angular characteristics of the radiation of a charged particle in a combination of the field of a plane monochromatic electromagnetic wave and a constant magnetic field, the so-called Redmond field. According to the calculated formulas for the radiation intensity of particles in the Redmond field, graphs of the dependence on the magnitude of the magnetic field, phase and phase-angular distributions are plotted. The Fourier transform of the intensity of the electric field of the radiation and the spectral density of the radiation of the particle in the case of linear polarization of the wave is obtained.

Spectral-angular characteristics of the radiation of a charged particle in the Redmond field

Based on the solution of the equation of motion of a charge in an electromagnetic field, the classical theory of radiation of a relativistic charged particle linearly accelerated by a high-intensity laser pulse in the presence of a static component of the magnetic field is constructed. Solutions obtained by Kopytov G.F. and Pogorelov A.V., were used to study the spectral-angular characteristics of the radiation of a charged particle in a combination of the field of a plane monochromatic electromagnetic wave and a constant magnetic field, the so-called Redmond field. According to the calculated formulas for the radiation intensity of particles in the Redmond field, graphs of the dependence on the magnitude of the magnetic field, phase and phase-angular distributions are plotted. The Fourier transform of the intensity of the electric field of the radiation and the spectral density of the radiation of the particle in the case of linear polarization of the wave is obtained. Keywords: Redmond field, spectral-angular characteristics, charged particle, Lawson-Woodward theorem, superpower laser radiation.

Modulated Laser-Induced Acceleration of a Relativistic Charged Particle

Modulated Laser-Induced Acceleration of a Relativistic Charged Particle

A study of maximum pseudorapidity gap distributions in 16O-nucleus interactions at 3.7, 60 and 200A GeV/c

The main aim of this paper is to present some interesting results on event-by-event maximum 2-particle gap ([Formula: see text]) in the pseudorapidity space of the relativistic charged particles [Formula: see text] produced in the [Formula: see text]O-AgBr interactions at 3.7, 60 and 200[Formula: see text]A GeV/c. The distribution of [Formula: see text] has been obtained for the experimental and AMPT simulated data. Distinct peaks are obtained in the [Formula: see text]-distributions of the relativistic charged particles in low [Formula: see text]-region. Further, the position of the peak is found to depend on the incident energy. The experimental results are not well supported by the results obtained for the AMPT simulated data. The findings presented here may be found useful in understanding the mechanism of the multiparticle production in relativistic nuclear interactions.

Quantum States of a Relativistic Charged Particle in Crossed Electric and Magnetic Fields

The exact eigenvalues and eigenfunctions of a spinless relativistic charged particle are obtained here. The results are compared with those from classical mechanics.

Novel tabletop experiment demonstrating the nonlinear resonance excitation observed at the CERN Proton Synchrotron

A compact Paul ion trap is employed to replicate the dynamic behavior of a relativistic charged-particle beam traveling in a large-scale accelerator. The nonlinear resonance bands recently identified at the CERN Proton Synchrotron (PS) are successfully reproduced in the tabletop system. The present experimental data suggests that all these resonances could be excited even without unknown error fields that break the high lattice symmetry of the PS. A new type of stability tune diagram appears to explain the basic feature of the experimental observation.

Asymptotic velocity of relativistic E × B drift

We have obtained the asymptotic velocity of a relativistic charged particle in static and uniform electric and magnetic fields with arbitrary orientations of the fields and with an arbitrary ratio of a = |E|/|B|, where the particle is assumed highly relativistic and has a constant velocity. The obtained solution corresponds to the relativistic E × B drift velocity of the guiding-center, which has features different from those of the non-relativistic drift velocity. The latter is given by vD/c = E × B/|B|2, but in the relativistic case, an additional drift motion exists in the direction that is perpendicular to both B and vD. The dependence of drift velocity on the angle between B and E is also modified substantially.

A study of relativistic charged secondaries produced in hadron-nucleus interactions

In this article, we report some results on pseudo-central collision events which have been observed in pion-nucleus interactions. It attempts to make a comparison, wherever possible, with proton-nucleus collisions. The particles are found to be produced in the form of clusters. The size of the cluster shows independence with the nature of the incident beam and energy. The short-short rapidity-gap correlation seems to dominate over the short-long correlation. Central and normalized moments of relativistic charged particles have been calculated and compared with the reported results for inclusive data. Both of them seem to increase with the order for inclusive data whereas their values are almost constant for pseudo-central collision events.

Determination of Zenith Angle Dependence of Incoherent Cosmic Ray Muon Flux Using Smartphones of the CREDO Project

The Cosmic-Ray Extremely Distributed Observatory (CREDO) was established to detect and study ultra high-energy cosmic ray particles. In addition to making use of traditional methods for finding rare and extended cosmic ray events such as professional-grade Extensive Air Shower (EAS) arrays, as well as educational ‘class-room’ detectors, CREDO also makes use of cameras in smartphones as particle detectors. Beyond the primary scientific goal of the CREDO project, to detect Cosmic Ray Ensembles, is the equally important educational goal of the project. To use smartphones for EAS detection, it is necessary to demonstrate that they are capable of effectively registering relativistic charged particles. In this article, we show that the events recorded in the CREDO project database are indeed tracing incoherent cosmic ray muons. The specific observed distribution of zenith angle of charged particle direction corresponds to that expected for muons. It is difficult, if not impossible, to imagine different mechanisms leading to such a distribution, and we believe it clearly demonstrates the suitability of smartphone-based detectors in supporting the more traditional cosmic ray detectors.

Oscillator model applied to 2D materials: Energy loss of relativistic charged particles

In this work we present a fully relativistic formulation for the energy loss of an external charged particle interacting with a 2D material. We model this material as a monolayer of atoms represented by harmonic oscillators, with isotropic or anisotropic electronic vibration modes. We develop the model for a wide range of incident energies and considering both parallel and perpendicular trajectories.