The telegraph equation in charged particle transport
Gombosi, T. I.; Jokipii, J. R.; Kota, J.; Lorencz, K.; Williams, L. L.
1993-01-01
We present a new derivation of the telegraph equation which modifies its coefficients. First, an infinite order partial differential equation is obtained for the velocity space solid angle-averaged phase-space distribution of particles which underwent at least a few collisions. It is shown that, in the lowest order asymptotic expansion, this equation simplifies to the well-known diffusion equation. The second-order asymptotic expansion for isotropic small-angle scattering results in a modified telegraph equation with a signal propagation speed of v(5/11) exp 1/2 instead of the usual v/3 exp 1/2. Our derivation of a modified telegraph equation follows from an expansion of the Boltzmann equation in the relevant smallness parameters and not from a truncation of an eigenfunction expansion. This equation is consistent with causality. It is shown that, under steady state conditions in a convecting plasma, the telegraph equation may be regarded as a diffusion equation with a modified transport coefficient, which describes a combination of diffusion and cosmic-ray inertia.
Effects of dispersive wave modes on charged particles transport
Schreiner, Cedric
2015-01-01
The transport of charged particles in the heliosphere and the interstellar medium is governed by the interaction of particles and magnetic irregularities. For the transport of protons a rather simple model using a linear Alfv\\'en wave spectrum which follows the Kolmogorov distribution usually yields good results. Even magnetostatic spectra may be used. For the case of electron transport, particles will resonate with the high-k end of the spectrum. Here the magnetic fluctuations do not follow the linear dispersion relation, but the kinetic regime kicks in. We will discuss the interaction of fluctuations of dispersive waves in the kinetic regime using a particle-in-cell code. Especially the scattering of particles following the idea of Lange et al. (2013) and its application to PiC codes will be discussed. The effect of the dispersive regime on the electron transport will be discussed in detail.
Optimizing interactive program for charged particle transport system design
A computer program for charged particle transport system design is described. The program is written in the BASIC language and allows one to make calculations in dialogue with the computer. The BASTRA program permits to get output information both in digital and in graphical forms. The method for optimization is described, that allows one to put 10 limitation on beam parameters in arbitrary places of the transport system. The program can be adapted on every computer having the BASIC language in its software
The Boltzmann equation theory of charged particle transport
It is shown how a formally exact Kubo-like response theory equivalent to the Boltzmann equation theory of charged particle transport can be constructed. The response theory gives the general wavevector and time-dependent velocity distribution at any time in terms of an initial distribution function, to which is added the response induced by a generalized perturbation over the intervening time. The usual Kubo linear response result for the distribution function is recovered by choosing the initial velocity distribution to be Maxwellian. For completeness the response theory introduces an exponential convergence function into the response time integral. This is equivalent to using a modified Boltzmann equation but the general form of the transport theory is not changed. The modified transport theory can be used to advantage where possible convergence difficulties occur in numerical solutions of the Boltzmann equation. This paper gives a systematic development of the modified transport theory and shows how the response theory fits into the broader scheme of solving the Boltzmann equation. The discussion extends both the work of Kumar et al. (1980), where the distribution function is expanded out in terms of tensor functions, and the propagator description where the non-hydrodynamic time development of the distribution function is related to the wavevector dependent Green function of the Boltzmann equation
TRANSPORT - a computer program for designing charged particle beam transport systems
TRANSPORT is a computer program for first-order and second-order matrix multiplication, intended for the design of static-magnetic beam-transport systems. It has been in existence in various versions since 1963. The first part of the report is a user's manual, and supersedes the earlier report CERN 73-16. The second part is a reproduction of the Fermilab document 'TRANSPORT appendix', by the same authors, which describes the theory of charged-particle beam optics and the applications of transformation matrices for numerical computation of beam trajectories and properties, as applied in the program. (orig.)
Transport of Charged Particles: Entropy Production and Maximum Dissipation Principle
Hsieh, Chia-Yu; Hyon, YunKyong; Lee, Hijin; Lin, Tai-Chia; Liu, Chun
2014-01-01
In order to describe the dynamics of crowded ions (charged particles), we use an energetic variation approach to derive a modified Poisson-Nernst-Planck (PNP) system which includes an extra dissipation due to the effective velocity differences between ion species. Such a system is more complicated than the original PNP system but with the same equilibrium states. Using Schauder's fixed-point theorem, we develop a local existence theorem of classical solutions for the modified PNP system. Diff...
Charged Particle Energization and Transport in the Magnetotail during Substorms
Pan, Qingjiang
This dissertation addresses the problem of energization of particles (both electrons and ions) to tens and hundreds of keV and the associated transport process in the magnetotail during substorms. Particles energized in the magnetotail are further accelerated to even higher energies (hundreds of keV to MeV) in the radiation belts, causing space weather hazards to human activities in space and on ground. We develop an analytical model to quantitatively estimate flux changes caused by betatron and Fermi acceleration when particles are transported along narrow high-speed flow channels from the magnetotail to the inner magnetosphere. The model shows that energetic particle flux can be significantly enhanced by a modest compression of the magnetic field and/or shrinking of the distance between the magnetic mirror points. We use coordinated spacecraft measurements, global magnetohydrodynamic (MHD) simulations driven by measured upstream solar wind conditions, and large-scale kinetic (LSK) simulations to quantify electron local acceleration in the near-Earth reconnection region and nonlocal acceleration during plasma earthward transport. Compared to the analytical model, application of the LSK simulations is much less restrictive because trajectories of millions of test particles are calculated in the realistically determined global MHD fields and the results are statistical. The simulation results validated by the observations show that electrons following a power law distribution at high energies are generated earthward of the reconnection site, and that the majority of the energetic electrons observed in the inner magnetosphere are caused by adiabatic acceleration in association with magnetic dipolarizations and fast flows during earthward transport. We extend the global MHD+LSK simulations to examine ion energization and compare it with electron energization. The simulations demonstrate that ions in the magnetotail are first nonadiabatically accelerated in the weak
Charged-Particle Bean Transport for Ion Trapping Experiments.
Raichle, Brian W.; Wingfield, Love M.
2001-11-01
Electrostatic Einsel lenses are being developed for beam transport for use in two distinct metastable atomic lifetime experiments using two separate rf-ion traps. Each system has been modeled using Simion software, and the lenses have been designed from commercially available eV-parts. The first application is part of an electron gun source. Electrons are produced by a conventional dispenser cathode and are transported 25 cm to the trap. The design goal is to create a beam divergence to fully illuminate the active trap volume, and to provide tunable electron energies from 50 to 500 eV. The second application is to transport ions 1 m from a laser ablation ion source to an rf ion trap. Laser ablation involves essentially boiling ions from a solid target with intense laser pulses. Here, the design goal is to maximize flux by maximizing the solid angle of acceptance to the trap, minimize radial velocity, and minimize the spread in axial velocity. Development of a laser ablation ion source external to the trap volume will allow a very low base pressure in the trap region, which will make possible the study of species with lifetimes approaching 1 s. In addition, laser ablation will produce intermediately-charged ions from non-conductive solid targets.
Kinetic phenomena in charged particle transport in gases and plasmas
Petrovic, Zoran Lj.; Dujko, Sasa; Sasic, Olivera; Stojanovic, Vladimir; Malovic, Gordana [Institute of Physics, University of Belgrade, POB 68 11080 Zemun (Serbia); Faculty of Traffic Engineering, University of Belgrade Belgrade (Serbia); Institute of Physics, University of Belgrade, POB 68 11080 Zemun (Serbia)
2012-05-25
The key difference between equilibrium (thermal) and non-equilibrium (low temperature - a.k.a. cold) plasmas is in the degree in which the shape of the cross sections influences the electron energy distribution function (EEDF). In this paper we will discuss the issue of kinetic phenomena from two different angles. The first will be how to take advantage of the strong influence and use low current data to obtain the cross sections. This is also known as the swarm technique and the product of a ''swarm analysis'' is a set of cross sections giving good number, momentum and energy balances of electrons or other charged particles. At the same time understanding the EEDF is based on the cross section data. Nevertheless sometimes the knowledge of the cross sections and even the behaviour of individual particles are insufficient to explain collective behaviour of the ensemble. The resulting ''kinetic'' effects may be used to favour certain properties of non-equilibrium plasmas and even may be used as the basis of some new plasma applications.
Roelof, E. C.
2015-09-01
“Reservoirs” of energetic charged particles are regions where the particle population is quasi-trapped in large-scale (relative to the gyroradii) magnetic field structures. Reservoirs are found throughout the heliosphere: the huge heliosheath (90appropriate description of this transport is “weak scattering”, in which the particle's first adiabatic invariant (magnetic moment) is approximately conserved while the particle itself moves rather freely along magnetic field lines. Considerable insight into the observed properties of energization processes can be gained from a remarkably simple equation that describes the particle's fractional time-rate-of-change of momentum (dlnp/dt) which depends only upon its pitch angle, the divergence of the plasma velocity (V⊥) transverse to the magnetic field), and the inner product of (V⊥) with the curvature vector of the field lines. The possibilities encompassed in this simple (but general) equation are quite rich, so we restrict our application of it in this paper to the compressive acceleration of SEPs within CMEs.
Attenuation of DNA charge transport by compaction into a nucleosome core particle
Bjorklund, Chad C.; Davis, William B.
2006-01-01
The nucleosome core particle (NCP) is the fundamental building block of chromatin which compacts ∼146 bp of DNA around a core histone protein octamer. The effects of NCP packaging on long-range DNA charge transport reactions have not been adequately assessed to date. Here we study DNA hole transport reactions in a 157 bp DNA duplex (AQ-157TG) incorporating multiple repeats of the DNA TG-motif, a strong NCP positioning sequence and a covalently attached Anthraquinone photooxidant. Following a ...
Adomian decomposition method for solving the telegraph equation in charged particle transport
In this paper, the analysis for the telegraph equation in case of isotropic small angle scattering from the Boltzmann transport equation for charged particle is presented. The Adomian decomposition is used to solve the telegraph equation. By means of MAPLE the Adomian polynomials of obtained series (ADM) solution have been calculated. The behaviour of the distribution function are shown graphically. The results reported in this article provide further evidence of the usefulness of Adomain decomposition for obtaining solution of linear and nonlinear problems
Simulation of neutron transport process, photons and charged particles within the Monte Carlo method
Description is given to the program system BRAND designed for the accurate solution of non-stationary transport equation of neutrons, photons and charged particles in the conditions of real three-dimensional geometry. An extensive set of local and non-local estimates provides an opportunity of calculating a great set of linear functionals normally being of interest in the calculation of reactors, radiation protection and experiment simulation. The process of particle interaction with substance is simulated on the basis of individual non-group data on each isotope of the composition. 24 refs
Momentum - transfer approximation is applied to momentum and energy balance equations describing reacting particle swarms in gases in crossed electric and magnetic fields. Transport coefficients of charged particles undergoing both inelastic and reactive, non-particle-conserving collisions with a gas of neutral molecules are calculated. Momentum - transfer theory (MTT) has been developed mainly by Robson and collaborators. It has been applied to a single reactive gas and mixtures of reactive gases in electric field only. MTT has also been applied in crossed electric and magnetic fields recently and independently of our work but the reactive collisions were not considered. Consider a swarm of electrons of charge e and mass m moving with velocity rvec v through a neutral gas under the influence of an applied electric rvec E and magnetic rvec B field. The collision processes which we shall investigate are limited to elastic, inelastic and reactive collisions of electrons with gas molecules. Here we interpret reactive collisions as collisions which produce change in number of the swarm particles. Reactive collisions involve creation (ionization by electron impact) or loss (electron attachment) of swarm particles. We consider only single ionization in approximation of the mass ratio m/m00 are masses of electrons and neutral particles, respectively. We assume that the stage of evolution of the swarm is the hydrodynamic limit (HDL). In HDL, the space - time dependence of all properties is carried by the number density n of swarm particles
In this paper we investigate charged particle transport and acceleration in a two-dimensional system with an uniform electric field and stationary magnetic field fluctuations. The main idea of this study is to consider dependencies of transport and acceleration rates on properties of distributions of magnetic field fluctuations. We develop a simplified model of magnetic fluctuations with a regulated distribution and apply the test particle approach. System parameters are chosen to simulate conditions typical for ion dynamics in the deep Earth magnetotail. We show that for a fixed power density of magnetic field fluctuations the particle acceleration is more effective in the system where particles interact with small-amplitude (but frequent) fluctuations. In systems with large-amplitude rare fluctuations the particle scattering is less effective and the particle acceleration is weaker. - Highlights: • Ion transport/acceleration by magnetic fluctuations with different distributions. • The most effective acceleration is for non-Gaussian magnetic field fluctuations • Both Gaussian/non-Gaussian distributions give similar energy spectrum shape
This document is a basic course on charged particle sources for post-graduate students and thematic schools on large facilities and accelerator physics. A simple but precise description of the creation and the emission of charged particles is presented. This course relies on every year upgraded reference documents. Following relevant topics are considered: electronic emission processes, technological and practical considerations on electron guns, positron sources, production of neutral atoms, ionization, plasma and discharge, different types of positive and negative ion sources, polarized particle sources, materials for the construction of ion sources, low energy beam production and transport. (N.T.)
Fujita, Yosuke; Kobayashi, Motoyoshi
2016-07-01
We have studied the transport of colloidal silica in various degrees of a water-saturated Toyoura sand column, because silica particles are widely used as catalyst carriers and abrasive agents, and their toxicity is reported recently. Since water-silica, water-sand, and air-water interfaces have pH-dependent negative charges, the magnitude of surface charge was controlled by changing the solution pH. The results show that, at high pH conditions (pH 7.4), the deposition of colloidal silica to the sand surface is interrupted and the silica concentration at the column outlet immediately reaches the input concentration in saturated conditions. In addition, the relative concentration of silica at the column outlet only slightly decreases to 0.9 with decreasing degrees of water saturation to 38%, because silica particles are trapped in straining regions in the soil pore and air-water interface. On the other hand, at pH 5 conditions (low pH), where sand and colloid have less charge, reduced repulsive forces result in colloidal silica attaching onto the sand in saturated conditions. The deposition amount of silica particles remarkably increases with decreasing degrees of water saturation to 37%, which is explained by more particles being retained in the sand column associated with the air-water interface. In conclusion, at higher pH, the mobility of silica particles is high, and the air-water interface is inactive for the deposition of silica. On the other hand, at low pH, the deposition amount increases with decreasing water saturation, and the particle transport is inhibited. PMID:27045635
A Generalized Boltzmann Fokker-Planck Method for Coupled Charged Particle Transport
Prinja, Anil K
2012-01-09
The goal of this project was to develop and investigate the performance of reduced-physics formulations of high energy charged particle (electrons, protons and heavier ions) transport that are computationally more efficient than not only analog Monte Carlo methods but also the established condensed history Monte Carlo technique. Charged particles interact with matter by Coulomb collisions with target nuclei and electrons, by bremsstrahlung radiation loss and by nuclear reactions such as spallation and fission. Of these, inelastic electronic collisions and elastic nuclear collisions are the dominant cause of energy-loss straggling and angular deflection or range straggling of a primary particle. These collisions are characterized by extremely short mean free paths (sub-microns) and highly peaked, near-singular differential cross sections about forward directions and zero energy loss, with the situation for protons and heavier ions more extreme than for electrons. For this reason, analog or truephysics single-event Monte Carlo simulation, while possible in principle, is computationally prohibitive for routine calculation of charged particle interaction phenomena.
BEAMR: An interactive graphic computer program for design of charged particle beam transport systems
Leonard, R. F.; Giamati, C. C.
1973-01-01
A computer program for a PDP-15 is presented which calculates, to first order, the characteristics of charged-particle beam as it is transported through a sequence of focusing and bending magnets. The maximum dimensions of the beam envelope normal to the transport system axis are continuously plotted on an oscilloscope as a function of distance along the axis. Provision is made to iterate the calculation by changing the types of magnets, their positions, and their field strengths. The program is especially useful for transport system design studies because of the ease and rapidity of altering parameters from panel switches. A typical calculation for a system with eight elements is completed in less than 10 seconds. An IBM 7094 version containing more-detailed printed output but no oscilloscope display is also presented.
The programme library for numerical simulation of charged particle dynamics in transportation lines
The description of a PC codes library to simulate the beam transportation of charged particles is presented. The codes are realized on IBM PC in Visual Basic common interface. It is destined for the simulation and optimization of beam dynamics and based on the successive and consistent use of two methods: the momentum method of distribution functions (RMS technique) and the particle-particle method (PP-Method). The library allows to calculate the RMS parameters of electron and ion beams, passing through a set of quadrupoles, solenoids, bends, accelerating sections. The RMS code is a fast code very suitable for the first test, design and optimization of the beam line parameters. The PP code requires more time for execution but provides a high accuracy of simulation taking into account the space charge effects, aberrations and beam losses. One of the main advantages of PP code presented here is an ability to simulate a real multicomponent beam of different masses and charged states of ions from ion sources
Earl, J. A.
1974-01-01
The uniqueness and accuracy of the equations which describe the transport of charged particles diffusing in a random magnetic field parallel to a relatively large guiding field is examined. With regard to uniqueness, it is found that the same coefficient of diffusion is obtained by three methods that have apparently led to discrepancies in previous work. With regard to accuracy, it is found that two corrections must be added to Fick's law in which the diffusive flux is proportional to the gradient of the density. Explicit expressions are given for a characteristic time and a characteristic length which describe the corrections.
This paper reviews the formulation and updates some numerical procedures usually adopted in two-dimensional, time-dependent fluid models to study the transport of charged particles in radio-frequency capacitively coupled discharges. The description of charged particle transport is made by solving the continuity and momentum transfer equations for electrons and ions, coupled with Poisson's equation and the electron mean energy transport equations. Inertia terms are considered in the ion momentum transfer equations, by generalizing the earlier definition of effective electric field. The electron mean energy equations are written using specific energy transport parameters, deduced from integration over the electron energy distribution function (EEDF). The model adopts the local mean energy approximation, i.e. it computes the electron transport parameters as a function of the electron mean energy, using either a homogeneous, two-term Boltzmann equation solver or a Maxwellian EEDF. More appropriate boundary conditions for the electron and ion fluxes are used successfully. The model is solved for a GEC Cell reactor type (with 6.4 cm radius and 3.2 cm interelectrode distance) operating at frequency 13.56 MHz, pressures between 10 mTorr and 10 Torr and applied voltages from 100 to 500 V, in electropositive (helium) and electronegative (silane-hydrogen) gases or gas mixtures. The ion kinetics in silane and hydrogen is updated with respect to previous works, by further considering SiH2+, H+ and H3+ ions. In general, simulation results for some typical electrical parameters are closer to experimental measurements available than calculations reported in previous works
Evaluation and comparison of SN and Monte-Carlo charged particle transport calculations
A study was done to evaluate a 3-D SN charged particle transport code called SMARTEPANTS1 and another 3-D Monte Carlo code called Integrated Tiger Series, ITS2. The evaluation study of SMARTEPANTS code was based on angular discretization and reflected boundary sensitivity whilst the evaluation of ITS was based on CPU time and variance reduction. The comparison of the two code was based on energy and charge deposition calculation in block of Gallium Arsenide with embedded gold cylinders. The result of evaluation tests shows that an S8 calculation maintains both accuracy and speed and calculations with reflected boundaries geometry produces full symmetrical results. As expected for ITS evaluation, the CPU time and variance reduction are opposite to a point beyond which the history augmentation while increasing the CPU time do not result in variance reduction. The comparison test problem showed excellent agreement in total energy deposition calculations
Transport and Acceleration of Energetic Charged Particles near an Oblique Shock
Ruffolo, D
1999-01-01
We have developed a numerical simulation code that treats the transport and acceleration of charged particles crossing an idealized oblique, non-relativistic shock within the framework of pitch angle transport using a finite-difference method. We consider two applications: 1) to study the steady-state acceleration of energetic particles at an oblique shock, and 2) to explain observed precursors of Forbush decreases of galactic cosmic rays before the arrival of an interplanetary shock induced by solar activity. For the former, we find that there is a jump in the particle intensity at the shock, which is stronger for more oblique shocks. Detailed pitch angle distributions are also presented. The simple model of a Forbush decrease explains the key features of observed precursors, an enhanced diurnal anisotropy extending several mean free paths upstream of the shock and a depletion of particles in a narrow loss cone at ~0.1 mean free path from the shock. Such precursors have practical applications for space weath...
OoTran, an object-oriented program for charged-particle beam transport design
The OoTran program is a new object-oriented program for charged-particle beam transport computation. Using a simple menu interface, the user builds his beam line with magnetic and electric elements taken from a standard library. The program computes the beam transport using a well-known first-order matrix formalism and displays 'in real time' the computed beam envelope. The menu editor provides functions to interactively modify the beam line. Ootran is written in C++ and uses two object libraries: OOPS, the Object-Oriented Program Support Class Library, which is a collection of classes similar to those of Smalltalk-80; and InterViews, a C++ graphical-interface toolkit based on the X-Window system. OoTran is running on DECstation 3100, VAXstation 2000 and SUN 3, with the ULTRIX and SUN OS operating systems. (orig.)
Methods for two-dimensional charged-particle transport in collisionless plasmas
A new method for modeling multi-dimensional charged particle transport in self-consistent electric and magnetic fields is presented. An implicit formulation of the Vlasov-Maxwell equations removes the usual restrictions on time and mesh spacing so that low frequency and large scale-length plasma phenomena can be studied. The improvement over previous explicit methods is literally orders of magnitude. As developed in a new code VENUS, we describe the algorithm and its stability and accuracy properties. This method allows one to bridge the enormous gap between the high frequency short scale-length collective plasma phenomena and the slow time scales and large-scale lengths of hydrodynamic processes. It should result in a significant improvement of phenomenological models of transport in existing hydrodynamics codes. Applications are given that include the discovery of the important role of self-generated magnetic fields in the convective transport of electron energy in laser irradiated plasmas. The transport, which occurs in the magnetized collisionless plasma corona, carries energy large distances from the laser deposition region in agreement with a wide variety of experimental data on apparent inhibited electron transport and fast ion loss
Third-order TRANSPORT: A computer program for designing charged particle beam transport systems
TRANSPORT has been in existence in various evolutionary versions since 1963. The present version of TRANSPORT is a first-, second-, and third-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. This report discusses the following topics on TRANSPORT: Mathematical formulation of TRANSPORT; input format for TRANSPORT; summaries of TRANSPORT elements; preliminary specifications; description of the beam; physical elements; other transformations; assembling beam lines; operations; variation of parameters for fitting; and available constraints -- the FIT command
Strauss, R. D.; le Roux, J. A.; Engelbrecht, N. E.; Ruffolo, D.; Dunzlaff, P.
2016-07-01
We investigate the transport of charged particles across magnetic discontinuities, focusing specifically on stream interfaces associated with co-rotating interaction regions in the solar wind. We argue that the magnetic field fluctuations perpendicular to the magnetic discontinuity, and usually also perpendicular to the mean magnetic field, are strongly damped in the vicinity of such a magnetic structure, leading to anisotropic perpendicular diffusion. Assuming that perpendicular diffusion arises from drifts in a turbulent magnetic field, we adopt a simplified approach to derive the relevant perpendicular diffusion coefficient. This approach, which we believe gives the correct principal dependences as expected from more elaborate calculations, allows us to investigate transport in different turbulent geometries, such as longitudinal compressional turbulence that may be present near the heliopause. Although highly dependent on the (possibly anisotropic) perpendicular length scales and turbulence levels, we generally find perpendicular diffusion to be strongly damped at magnetic discontinuities, which may in turn provide an explanation for the large particle gradients associated with these structures.
TRANSPORT: a computer program for designing charged particle beam transport systems
TRANSPORT is a first- and second-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. It has been in existence in various evolutionary versions since 1963. The present version, described in the manual given, includes both first- and second-order fitting capabilities. TRANSPORT will step through the beam line, element by element, calculating the properties of the beam or other quantities, described below, where requested. Therefore one of the first elements is a specification of the phase space region occupied by the beam entering the system. Magnets and intervening spaces and other elements then follow in the sequence in which they occur in the beam line. Specifications of calculations to be done or of configurations other than normal are placed in the same sequence, at the point where their effect is to be made
TRANSPORT: a computer program for designing charged particle beam transport systems
Brown, K.L.; Rothacker, F.; Carey, D.C.; Iselin, C.
1977-05-01
TRANSPORT is a first- and second-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. It has been in existence in various evolutionary versions since 1963. The present version, described in the manual given, includes both first- and second-order fitting capabilities. TRANSPORT will step through the beam line, element by element, calculating the properties of the beam or other quantities, described below, where requested. Therefore one of the first elements is a specification of the phase space region occupied by the beam entering the system. Magnets and intervening spaces and other elements then follow in the sequence in which they occur in the beam line. Specifications of calculations to be done or of configurations other than normal are placed in the same sequence, at the point where their effect is to be made.
The process of angular-spatial evolution of multiple scattering of charged particles can be described by a special case of Boltzmann integro-differential equation called Lewis equation. The underlying stochastic process for this evolution is the compound Poisson process on the surface of the unit sphere. The significant portion of events that constitute compound Poisson process that describes multiple scattering have diffusional character. This property allows to analyze the process of angular-spatial evolution of multiple scattering of charged particles as combination of soft and hard collision processes and compute appropriately its transition densities. These computations provide a method of the approximate solution to the Lewis equation. (orig.)
The role of the Wigner function in charged-particle beam transport
Fedele Renato
2014-01-01
Full Text Available The role of the Wigner function in the dynamics of charged particle beams in high-energy accelerating machines is discussed. This is done within the quantum-like description of the thermal wave model (TWM. A brief review of the numerical experiments showing satisfactory agreement between TWM and the particle tracking simulations is presented. A simple analysis in phase space in terms of the Wigner quasidistribution, showing that TWM is capable of reproducing the beam dynamics in the presence of the space charge effects, is put froward.
Chubb, Scott R
2005-01-01
As opposed to the conventional, approximate theory of electrical conduction in solids, which is based on energy band, quasi-particle states in infinite lattices, a rigorous theory exists that can be used to explain transport phenomena, in finite lattices, at reduced temperature, through the effects of a broken gauge symmetry: The loss of translational invariance with respect to Galilean transformations that maintain particle-particle separation. Implications of this result in areas related to...
Study of CHarged particles transport across model and real phospholipid bilayers
Navrátil, Tomáš; Šestáková, Ivana; Jaklová Dytrtová, Jana; Jakl, M.; Mareček, Vladimír
Tenerife: WSEAS Press, 2009 - (Bulucea, C.; Mladenov, V.; Pop, E.; Leba, M.; Mastorakis, N.), s. 212-217 ISBN 978-960-474-142-7. [International Conference on Environment, Ecosystems and Development (EED ´09) /7./. Tenerife (ES), 14.12.2009-16.12.2009] R&D Projects: GA AV ČR IAA400400806 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40550506 Keywords : phospholipid bilayers * environment * trace elements * charged particles Subject RIV: CF - Physical ; Theoretical Chemistry
Humphries, Stanley
2013-01-01
Detailed enough for a text and sufficiently comprehensive for a reference, this volume addresses topics vital to understanding high-power accelerators and high-brightness-charged particle beams. Subjects include stochastic cooling, high-brightness injectors, and the free electron laser. Humphries provides students with the critical skills necessary for the problem-solving insights unique to collective physics problems. 1990 edition.
Charged Particle Optics Theory
Hawkes, P. W.; Lencová, Bohumila
-, č. 6 (2006), s. 6-8 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Keywords : optics of charged particles * design of ion lithography system * spot profile * the finite element method Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www.phantomsnet.net
Yang, Y. M.; Bednarz, B.
2013-02-01
Following the proposal by several groups to integrate magnetic resonance imaging (MRI) with radiation therapy, much attention has been afforded to examining the impact of strong (on the order of a Tesla) transverse magnetic fields on photon dose distributions. The effect of the magnetic field on dose distributions must be considered in order to take full advantage of the benefits of real-time intra-fraction imaging. In this investigation, we compared the handling of particle transport in magnetic fields between two Monte Carlo codes, EGSnrc and Geant4, to analyze various aspects of their electromagnetic transport algorithms; both codes are well-benchmarked for medical physics applications in the absence of magnetic fields. A water-air-water slab phantom and a water-lung-water slab phantom were used to highlight dose perturbations near high- and low-density interfaces. We have implemented a method of calculating the Lorentz force in EGSnrc based on theoretical models in literature, and show very good consistency between the two Monte Carlo codes. This investigation further demonstrates the importance of accurate dosimetry for MRI-guided radiation therapy (MRIgRT), and facilitates the integration of a ViewRay MRIgRT system in the University of Wisconsin-Madison's Radiation Oncology Department.
Magnetic guidance of charged particles
Dubbers, Dirk
2015-01-01
Many experiments and devices in physics use static magnetic fields to guide charged particles from a source onto a detector, and we ask the innocent question: What is the distribution of particle intensity over the detector surface? One should think that the solution to this seemingly simple problem is well known. We show that, even for uniform guide fields, this is not the case and present analytical point spread functions (PSF) for magnetic transport that deviate strongly from previous results. The "magnetic" PSF shows unexpected singularities, which were recently also observed experimentally, and which make detector response very sensitive to minute changes of position, field amplitude, or particle energy. In the field of low-energy particle physics, these singularities may become a source of error in modern high precision experiments, or may be used for instrument tests, for instance in neutrino mass retardation spectrometers.
Magnetic guidance of charged particles
Dirk Dubbers
2015-09-01
Full Text Available Many experiments and devices in physics use static magnetic fields to guide charged particles from a source onto a detector, and we ask the innocent question: What is the distribution of particle intensity over the detector surface? One should think that the solution to this seemingly simple problem is well known. We show that, even for uniform guide fields, this is not the case, and we present analytical point spread functions (PSF for magnetic transport that deviate strongly from previous results. The “magnetic” PSF shows unexpected singularities, which were recently also observed experimentally, and which make detector response very sensitive to minute changes of position, field amplitude, or particle energy. In the field of low-energy particle physics, these singularities may become a source of error in modern high precision experiments, or may be used for instrument tests.
Charged and neutral particle transport methods and applications: The CALOR code system
Gabriel, T.A.; Charlton, L.A.
1997-04-01
The CALOR code system, which is a complete radiation transport code system, is described with emphasis on the high-energy (> 20 MeV) nuclear collision models. Codes similar to CALOR are also briefly discussed. A current application using CALOR which deals with the development of the National Spallation Neutron Source is also given.
Nanodosimetry of charged particles
In last year's annual report, the authors described the development of an ultra-miniature counter (UMC), described some of its physical characteristics, and presented some first measurements with this counter of microdosimetric spectra for neutrons (15 MeV) and photons (137Cs). It remains to investigate in more detail the operational characteristics of the UMC and if possible, to make a comparison of relevant physical parameters such as gain and multiplication radius with the Segur theory. In order to accomplish these objectives, it is necessary to build a wall-less version of the UMC, which will be amenable to calibration and investigation with collimated beams of charged particles. The design of such a counter has been worked out in principle. Investigations into the optimal design of electrode structures and dimensions are being carried out at present. The main problem occurs with the design of the grid structure which is required to define the outer boundary of the collecting volume. Our initial attempts would make it appear at present that a counter of 1 to 1.5 mm diameter is feasible. This should be more than adequate to provide an appropriately wall-less counter within a reasonable size cavity. It will probably be about a year before a working counter can be produced. In the interim, it is possible to make some initial efforts into the investigation of operational characteristics of a wall-less UMC by making use of similar design, but at a somewhat larger size. These first attempts at measurement of charged particle microdosimetric spectra at nanometer site provide added evidence that these counters can yield useful microdosimetric data at far smaller site sizes than heretofore attempted. They also provide added incentive and encouragement for development of wall-less UMC
Matching the phase volume of a transported charged particle beam by a doublet of quadrupole lenses
The problem of matching the phase volume of a transported beam is commonly solved by nonlinear programming methods. Writing a system of matching equations that is transcendental, one can turn to the following stage: its solution by direct numerical methods. In this paper the system of matching equations will be reduced to one equation with one unknown by means of successive analytical transformations. This was achieved by the corresponding substitution of the variables. The last equation was solved on a computer. As a result, such characteristics as drift lengths, lengths and gradients of magnetic lenses are written analytically depending on the chosen vector of the parameters and the unknown quantity as indicated. The formulas obtained are realized as a FORTRAN program on a CDC-6500 computer. In the user's dialogue with the computer, this program allows to correct fast all values of free parameters and to choose the most economical version of the calculated matching structure. Geometrical and magnetic characteristics of the beam transport system under investigation are presented in the version conclusively chosen. (orig.)
SIMPLIFIED CHARGED PARTICLE BEAM TRANSPORT MODELING USING COMMONLY AVAILABLE COMMERCIAL SOFTWARE
Particle beam modeling in accelerators has been the focus of considerable effort since the 1950s. Many generations of tools have resulted from this process, each leveraging both prior experience and increases in computer power. However, continuing innovation in accelerator technology results in systems that are not well described by existing tools, so the software development process is on-going. We discuss a novel response to this situation, which was encountered when Jefferson Lab began operation of its energy-recovering linacs. These machines were not readily described with legacy soft-ware; therefore a model was built using Microsoft Excel. This interactive simulation can query data from the accelerator, use it to compute machine parameters, analyze difference orbit data, and evaluate beam properties. It can also derive new accelerator tunings and rapidly evaluate the impact of changes in machine configuration. As it is spreadsheet-based, it can be easily user-modified in response to changing requirements. Examples for the JLab IR Upgrade FEL are presented
Plasma-based accelerator schemes represent the first step of the research-development of the future accelerator machines. Within the Vlasov's kinetic theory, describing the plasma wake field interaction, the collective transport of a warm non-laminar relativistic charged particle beam is analyzed in the strongly nonlocal regime, where the beam spot-size is much less than the plasma wavelength. This is done in the overdense regime, i.e., the beam density is much less than the plasma density. The beam is supposed to be sufficiently long to experience the adiabatic shielding by the plasma. In these conditions, we neglect the longitudinal beam dynamics and focus on the transverse one only. We derive the virial description (envelope description) from the 2D Vlasov-Poisson-type system of equations that governs the transverse self-consistent plasma wake field excitation. The resulting envelope equation is then reduced, in the aberration-less approximation, to a differential equation for the beam spot size, where the role of the ambient magnetic field is evaluated in both laboratory and astrophysical environments. An analysis of the beam envelope self-modulation is then carried out and the criteria for the occurrence of the instability are found. (authors)
Das, B. K.; Hazarika, P.; Chakraborty, M.; Bandyopadhyay, M.
2014-07-01
A study on the transport of charged particles across a magnetic filter field has been carried out in a double plasma device (DPD) and presented in this manuscript. The DPD is virtually divided into two parts viz. source and target regions by a transverse magnetic field (TMF) which is constructed by inserting strontium ferrite magnets into two stainless steel rectangular tubes. Plasma electrons are magnetized but ions are unmagnetized inside the TMF region. Negative voltages are applied to the TMF tubes in order to reduce the loss of electrons towards them. Plasma is produced in the source region by filament discharge method and allowed to flow towards the target region through this negatively biased TMF. It is observed that in the target region, plasma density can be increased and electron temperature decreased with the help of negatively biased TMF. This observation is beneficial for negative ion source development. Plasma diffusion across the negatively biased TMF follows Bohm or anomalous diffusion process when negative bias voltage is very less. At higher negative bias, diffusion coefficient starts deviating from the Bohm diffusion value, associated with enhanced plasma flow in the target region.
Surface charge accumulation of particles containing radionuclides in open air
Radioactivity can induce charge accumulation on radioactive particles. However, electrostatic interactions caused by radioactivity are typically neglected in transport modeling of radioactive plumes because it is assumed that ionizing radiation leads to charge neutralization. The assumption that electrostatic interactions caused by radioactivity are negligible is evaluated here by examining charge accumulation and neutralization on particles containing radionuclides in open air. A charge-balance model is employed to predict charge accumulation on radioactive particles. It is shown that particles containing short-lived radionuclides can be charged with multiple elementary charges through radioactive decay. The presence of radioactive particles can significantly modify the particle charge distribution in open air and yield an asymmetric bimodal charge distribution, suggesting that strong electrostatic particle interactions may occur during short- and long-range transport of radioactive particles. Possible effects of transported radioactive particles on electrical properties of the local atmosphere are reported. The study offers insight into transport characteristics of airborne radionuclides. Results are useful in atmospheric transport modeling of radioactive plumes. - Highlights: • Radioactivity-induced charge enhances electrostatic particle interactions. • Radioactivity-induced particle charging is important in radioactivity transport. • Ionization rate coefficients of beta-emitting radionuclides are reported
Heavy charged particle therapy
A pilot study of heavy charged particles with heavy ion medical accelerator in Chiba (HIMAC) for advanced H and N cancer has been carried out from June 1994 at National Institute of Radiological Sciences (NIRS). As of the beginning of August 1994, three patients were treated by 290 MeV carbon ions. The patients had adenocarcinoma of the cheek mucosa, squamous cell carcinoma of the ethmoid sinus and adenoid cystic carcinoma of the sublingual gland. Patients were immobilized by individual head coach and thermosplint facial shell. Individual collimators and bolus were also prepared for each ports. Dose fractionation for the initial pilot study group was 16.2 GyE/18 fractions/6 weeks, which would be equivalent to standard fractionation of 60.0 Gy/30 fractions/6 weeks with photons. This dose fractionation was considered to be 20% lesser than 75 GyE/37.5 fractions/7.5 weeks, which is estimated to be maximum tolerance dose for advanced H and N cancers. HIMAC worked well and there was no major trouble causing any treatment delay. Acute skin reactions of 3 patients were 2 cases of bright erythema with patchy moist desquamation and one of dull erythema, which were evaluated as equivalent reaction with irradiated dose. Acute mucosa reactions appeared to have lesser reaction than predicted mucositis. Tumor reactions of three patients were partial reaction (PR) at the end of treatment and nearly complete remission (CR) after 6 months of treatment. From October 1994, we started to treat patients with advanced H and N cancer with 10% high dose than previous dose. And new candidates of pilot study with non small cell lung cancer, brain tumor and carcinoma of the tongue were entered into pilot study. At the end of February 1995, a total of 21 patients were treated by carbon ions. (J.P.N.)
Using electrodes made of semi-conductive glass is an innovative way of improving the rate capability of resistive plate chambers. To address this issue, we developed 6- and 10-gap counters with low-resistive silicate glass electrodes (bulk resistivity ∼1010 Ω cm) suited for time-of-flight (TOF) applications at high rates and high transported charges. Measurements were performed at GSI-Darmstadt under uniform an irradiation by secondary particles stemming from proton reactions at 2.5 GeV/A. For the 10-gap MRPC, time resolutions below 90 ps and efficiencies larger than 90% were obtained at counting rates up to 25 kHz/cm2. When the particle flux increases every 5 kHz/cm2, the efficiency decreases by 1% and the time resolution deteriorates by 4 ps. A tolerable decrease of the material conductivity was also observed for a total transported charge of 1 C/cm2.
Suitable for both the specialist and non-specialist, this book develops all statements from first principles. Key chapters of the book focus upon how to design particle-optical systems, the systematics of image abberations, the effects of fringing fields, systematics of beams, and solutions for particle-optical systems. An undergraduate background in physics and mathematics is required for this work
Measuring momentum for charged particle tomography
Morris, Christopher; Fraser, Andrew Mcleod; Schultz, Larry Joe; Borozdin, Konstantin N.; Klimenko, Alexei Vasilievich; Sossong, Michael James; Blanpied, Gary
2010-11-23
Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive detectors to scatter in the position sensitive detectors. A controller can be adapted and arranged to receive scattering measurements of the charged particle from the charged particle detector, determine at least one trajectory of the charged particle from the measured scattering; and determine at least one momentum measurement of the charged particle from the at least one trajectory. The charged particle can be a cosmic ray-produced charged particle, such as a cosmic ray-produced muon. The position sensitive detectors can be drift cells, such as gas-filled drift tubes.
Dust particle charging in sheath
The charging and the screening of spherical dust particles in sheaths near the wall were studied using computer simulation. The three-dimensional PIC/MCC method and molecular dynamics method were applied to describe plasma particles motion and interaction with macroscopic dust grain. Calculations were carried out at different neutral gas pressures and wall potentials. Values of the charge of the dust particles and spatial distributions of plasma parameters are obtained by modelling. The results have shown that the charge of the dust particles in the sheath, as well as the spatial distribution of the ions and electrons near the dust particles, depend strongly on the wall potential. It is shown that for large negative values of the wall potential the negative charge of a dust particle decreases due to the decline of the electron density in its vicinity. In addition, the flow of energy of the ions on the surface of dust particles is increased due to better focusing effect of the dust particle field on ions.
Discrete Element Modeling of Triboelectrically Charged Particles
Hogue, Michael D.; Calle, Carlos I.; Weitzman, Peter S.; Curry, David R.
2008-01-01
Tribocharging of particles is common in many processes including fine powder handling and mixing, printer toner transport and dust extraction. In a lunar environment with its high vacuum and lack of water, electrostatic forces are an important factor to consider when designing and operating equipment. Dust mitigation and management is critical to safe and predictable performance of people and equipment. The extreme nature of lunar conditions makes it difficult and costly to carry out experiments on earth which are necessary to better understand how particles gather and transfer charge between each other and with equipment surfaces. DEM (Discrete Element Modeling) provides an excellent virtual laboratory for studying tribocharging of particles as well as for design of devices for dust mitigation and for other purposes related to handling and processing of lunar regolith. Theoretical and experimental work has been performed pursuant to incorporating screened Coulombic electrostatic forces into EDEM, a commercial DEM software package. The DEM software is used to model the trajectories of large numbers of particles for industrial particulate handling and processing applications and can be coupled with other solvers and numerical models to calculate particle interaction with surrounding media and force fields. While simple Coulombic force between two particles is well understood, its operation in an ensemble of particles is more complex. When the tribocharging of particles and surfaces due to frictional contact is also considered, it is necessary to consider longer range of interaction of particles in response to electrostatic charging. The standard DEM algorithm accounts for particle mechanical properties and inertia as a function of particle shape and mass. If fluid drag is neglected, then particle dynamics are governed by contact between particles, between particles and equipment surfaces and gravity forces. Consideration of particle charge and any tribocharging and
Johnson, W.L.; Crane, J.K.; Hendricks, C.D.
1980-08-29
Advanced target designs require thicker (approx. 300 ..mu..m) coatings and better surface finishes that can be produced with current coating techniques. An advanced coating technique is proposed to provide maximum control of the coating flux and optimum manipulation of the shell during processing. In this scheme a small beam of ions or particles of known incident energy are collided with a levitated spherical mandrel. Precise control of the incident energy and angle of the deposition flux optimizes the control of the coating morphology while controlled rotation and noncontact support of the shell minimizes the possibility of particulate or damage generated defects. Almost infinite variability of the incident energy and material in this process provides increased flexibility of the target designs which can be physically realized.
Advanced target designs require thicker (approx. 300 μm) coatings and better surface finishes that can be produced with current coating techniques. An advanced coating technique is proposed to provide maximum control of the coating flux and optimum manipulation of the shell during processing. In this scheme a small beam of ions or particles of known incident energy are collided with a levitated spherical mandrel. Precise control of the incident energy and angle of the deposition flux optimizes the control of the coating morphology while controlled rotation and noncontact support of the shell minimizes the possibility of particulate or damage generated defects. Almost infinite variability of the incident energy and material in this process provides increased flexibility of the target designs which can be physically realized
Charged particle acceleration with plasmas
Under certain conditions it is possible to create spatial charge waves (OCE) in a plasma (ionized gas) through some disturbance mechanism, the phenomenon produces electric fields of high intensity that are propagated at velocities near to a c. When charged particles are connected to such OCE they may be accelerated to very high energies in short distances. At present electric fields of approximately 107 V/cm have been observed. (Author). 4 refs
Guo, Fan
2012-01-01
After introduction we focus on: the transport of charged particles, the acceleration of ions at shocks, and the acceleration of electrons at shocks. Chapter 2 studies the propagation of solar energetic particles(SEPs) in turbulent magnetic fields. Particle trajectories in turbulent magnetic fields are numerically integrated. The turbulence includes a Kolmogorov-like power spectrum containing a broad range of scales. Small-scale variations in particle intensities(dropouts) and velocity dispersions can be reproduced. The result gives a constraint on the error of onset analysis for inferring SEP informations. We find that dropouts are rarely produced using the two-component model(Matthaeus et al., 1990). The result questions the turbulence model. Chapter 3 studies the acceleration of ions. We use 3-D hybrid simulations to study the acceleration of low-energy particles at parallel shocks. We find that particles gain energy by reflection at the shock. The protons can move off field lines in 3-D electric and magnet...
Space charge dominated beam transport
We consider beam transport systems where space charge forces are comparable in strength with the external focusing force. Space charge then plays an important role for beam transmission and emittance growth. We use the envelope model for matching and the generalized field energy equations to study emittance growth. Analytic results are compared with numerical simulation. (orig.)
The kinetic theory of charged particles in gases has come a long way in the last 60 years or so, but many of the advances have yet to find their way into contemporary studies of low-temperature plasmas. This review explores the way in which this gap might be bridged, and focuses in particular on the analytic framework and numerical techniques for the solution of Boltzmann's equation for both electrons and ions, as well as on the development of fluid models and semi-empirical formulae. Both hydrodynamic and non-hydrodynamic regimes are considered and transport properties are calculated in various configurations of dc and ac electric and magnetic fields. We discuss in particular the duality in transport coefficients arising from non-conservative collisions (attachment, ionization). (review article)
Geometrical charged-particle optics
Rose, Harald
2012-01-01
This second edition is an extended version of the first edition of Geometrical Charged-Particle Optics. The updated reference monograph is intended as a guide for researchers and graduate students who are seeking a comprehensive treatment of the design of instruments and beam-guiding systems of charged particles and their propagation in electromagnetic fields. Wave aspects are included in this edition for explaining electron holography, the Aharanov-Bohm effect and the resolution of electron microscopes limited by diffraction. Several methods for calculating the electromagnetic field are presented and procedures are outlined for calculating the properties of systems with arbitrarily curved axis. Detailed methods are presented for designing and optimizing special components such as aberration correctors, spectrometers, energy filters monochromators, ion traps, electron mirrors and cathode lenses. In particular, the optics of rotationally symmetric lenses, quadrupoles, and systems composed of these elements are...
Medium energy charged particle spectrometer
The charged particle spectrometer E8 on HELIOS A and B will be described in some detail. It covers proton energies from 80 keV to 6 MeV, electrons from 20 keV to 2 MeV, and positrons from 150 to 550 keV. Its flight performance will be discussed. From examples of measurements the capability of the instrument will be demonstrated. (orig.)
Computations in Charged Particle Optics
Oral, Martin; Radlička, Tomáš
Brno: Institute of Scientific Instruments AS CR, v. v. i, 2014, s. 23-24. ISBN 978-80-87441-12-1. [Workshop of Interesting Topics of SEM and ESEM. Mikulov (CZ), 26.08.2014-31.08.2014] R&D Projects: GA MŠk EE.2.3.20.0103 Institutional support: RVO:68081731 Keywords : charged Particle Optics * computations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Heavy charged particle radiotherapy trial
Through mid-1985, a total of 49 patients received heavy-charged-particle irradiation for chordoma, chondrosarcoma, meningioma, or neurilemmoma of the base of skull or juxtaspinal area. The mean tumor dose was 68 Gray-equivalent, ranging from 26 to 80. Control within the irradiated area was obtained in 35 of 49. The median follow up in all 49 patients is 21 months, with a range from 3-90 months. Serious complications were seen in a small number of patients, with cranial nerve injury in two, transverse myelitis in one, and brain necrosis in three patients. In 42 patients with tumors of other histologies and/or sites, including tumors of paranasal sinuses, retroperitoneum, soft tissue and miscellaneous other sites, heavy charged particles were also used to deliver a higher tumor dose than possible with standard irradiation techniques. In the group, 21/42 (50%) have had local tumor control, also a good result considering the extent and the range of tumor types treated. The authors believe that there are a number of sites in addition to the juxtaspinal/base of skull tumors that will show long term benefit from treatment with heavy charged particles
Grimes, B. A.; Liapis, A. I.
2001-02-01
Mass-transfer systems based on electrokinetic phenomena (i.e., capillary electrochromatography (CEC)) have shown practical potential for becoming powerful separation methods for the biotechnology and pharmaceutical industries. A dynamic mathematical model, consisting of the momentum balance and the Poisson equations, as well as the unsteady-state continuity expressions for the cation and anion of the background electrolyte and of a positively charged analyte (adsorbate), is constructed and solved to determine quantitatively the electroosmotic velocity, the electrostatic potential, the concentration profiles of the charged species in the double layer and in the electroneutral core region of the fluid in the interstitial channels for bulk flow in the packed chromatographic column, and the axial current density profiles as the adsorbate adsorbs onto the negatively charged fixed sites on the surface of the nonporous particles packed in the chromatographic column. The frontal analysis mode of operation is simulated in this work. The results obtained from model simulations provide significant physical insight into and understanding of the development and propagation of the dynamic profile of the concentration of the adsorbate (analyte) and indicate that sharp, highly resolved adsorption fronts and large amounts of adsorbate in the adsorbed phase for a given column length can be obtained under the following conditions: (i) The ratio, gamma(2, 0), of the electroosmotic velocity of the mobile liquid phase at the column entrance after the adsorption front has passed the column entrance to the electrophoretic velocity of the anion is very close to -1. The structure of the equations of the model and model simulations indicate that a stable adsorption front cannot develop when gamma(2, 0) is less than -1 unless the value of the mobility of the cation is less than the value of the mobility of the analyte, which may be a rare occurrence in practical CEC systems. (ii) The ratio of
Direct charged particle imaging sensors
CMOS image sensors optimized for charged particle imaging applications, such as electron microscopy and particle physics, have been designed and characterized. These directly image charged particles without reliance on performance-degrading hybrid technologies such as the use of scintillating materials. Based on standard CMOS active pixel sensor (APS) technology, the sensor arrays uses an 8-20 μm epitaxial layer that acts as a thicker sensitive region for the generation and collection of ionization electrons resulting from impinging high-energy particles. This results in a 100% fill factor and a far larger signal per incident electron than a standard CMOS photodiode could provide. A 512x550 pixels prototype has been fabricated and used extensively in an electron microscope, including having been used to take sample images. Temporal noise was measured to be 0.9 mV RMS, and the dynamic range was 60 dB. Power consumption at 70 frames/s is 20 mW. The full-width half-maximum of the collected ionization electron distribution was found to be 5.5 μm, yielding a spatial resolution of approximately 2.3 μm for individual incident electrons, and the modulation transfer function of the sensor at the Nyquist limit is to be 32%
The dynamics of a charged particle
Rohrlich, Fritz
2008-01-01
Using physical arguments, I derive the physically correct equations of motion for a classical charged particle from the Lorentz-Abraham-Dirac equations (LAD) which are well known to be physically incorrect. Since a charged particle can classically not be a point particle because of the Coulomb field divergence, my derivation accounts for that by imposing a basic condition on the external force. That condition ensures that the particle's finite size charge distribution looks like a point charg...
TURTLE is a computer program useful for determining many characteristics of a particle beam once an initial design has been achieved, Charged particle beams are usually designed by adjusting various beam line parameters to obtain desired values of certain elements of a transfer or beam matrix. Such beam line parameters may describe certain magnetic fields and their gradients, lengths and shapes of magnets, spacings between magnetic elements, or the initial beam accepted into the system. For such purposes one typically employs a matrix multiplication and fitting program such as TRANSPORT. TURTLE is designed to be used after TRANSPORT. For convenience of the user, the input formats of the two programs have been made compatible. The use of TURTLE should be restricted to beams with small phase space. The lumped element approximation, described below, precludes the inclusion of the effect of conventional local geometric aberrations (due to large phase space) or fourth and higher order. A reading of the discussion below will indicate clearly the exact uses and limitations of the approach taken in TURTLE
Interactions of charged dust particles in clouds of charges
Gundienkov, Vladimir; Yakovlenko, Sergey
2004-03-01
Two charged dust particles inside a cloud of charges are considered as Debye atoms forming a Debye molecule. Cassini coordinates are used for the numerical solution of the Poisson-Boltzmann equation for the charged cloud. The electric force acting on a dust particle by the other dust particle was determined by integrating the electrostatic pressure on the surface of the dust particle. It is shown that attractive forces appear when the following two conditions are satisfied. First, the average distance between dust particles should be approximately equal to two Debye radii. Second, attraction takes place when similar charges are concentrated predominantly on the dust particles. If the particles carry a small fraction of total charge of the same polarity, repulsion between the particles takes place at all distances. We apply our results to the experiments with thermoemission plasma and to the experiments with nuclear-pumped plasma.
Charge transport in nanoscale junctions.
Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas
2008-09-01
Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at
Heavy charged particle dosimetry, theory and application
Experiments were made to verify the theory of the transport of heavy particles through a medium using L-α-alaline for the detection of radiation. The dose response of L-α-alaline was measured for X-ray radiation of an energy of 4 to 16 MeV, electron radiation of an energy of 6, 10 and 20 MeV, low-LET radiation, 16 MeV and 6 MeV protons, 20 MeV particles and other charged particles. Of the measured dose responses RE values were experimentally obtained and compared with calculated results. Free and very stable radicals were obtained by radiation. Fading of low-LET and high-LET radiation was determined as induced by the said radicals. Using ESR spectra it was found that diverse chemical reactions take place in the track of high-LET particles. However, chemical reactions in the track of a heavy charged particle will be the same if the medium is homogeneously irradiated with low-LET radiation. (E.S.). 7 figs., 1 tab., 11 refs
Structural, transport and optical properties of nano-crystalline Pr0.6Ca0.4MnO3 have been investigated to emphasize on the semiconducting properties of charge-ordered manganite. Rietveld refinement of X-ray diffraction pattern of Pr0.6Ca0.4MnO3 nanoparticles show that due to increase in sintering temperature, MnO6 octahedra elongated along z-direction and compressed in x-y plane. Both Mn–O–Mn angles are found to decrease with increasing sintering temperature. Fourier transform infrared (FTIR) spectroscopy measurements reveal that the stretching and bending vibration of Mn–O–Mn is responsible for the change in Mn–O–Mn bond length and bond angle respectively. With increasing sintering temperature, these vibrations tend to increase, which resulted in the further distortion of MnO6 octahedra. Magnetic measurements suggest that charge ordering is established and system becomes antiferromagnetic with increasing particle size. Resistivity behavior of Pr0.6Ca0.4MnO3 nanoparticles clearly exhibit semiconducting nature of these systems, which is due to the formation of charge-ordered state of Mn3+ and Mn4+. Estimated optical band-gap of ∼3.7 eV for Pr0.6Ca0.4MnO3 nanocrystals, makes it a potential candidate for wide band-gap magnetic semiconductors. - Highlights: • Pr0.6Ca0.4MnO3 nanoparticles have been synthesized via sol–gel route. • Optical properties of charge-ordered Pr0.6Ca0.4MnO3 have been investigated. • Pr0.6Ca0.4MnO3 nanoparticles exhibit wide band-gap (3.7 eV) semiconducting nature. • Potential candidate for wide band-gap magnetic semiconductor device applications
Charge transport by holographic Fermi surfaces
Faulkner, Thomas; Liu, Hong; McGreevy, John; Vegh, David
2013-01-01
We compute the contribution to the conductivity from holographic Fermi surfaces obtained from probe fermions in an AdS charged black hole. This requires calculating a certain part of the one-loop correction to a vector propagator on the charged black hole geometry. We find that the current dissipation is as efficient as possible and the transport lifetime coincides with the single-particle lifetime. In particular, in the case where the spectral density is that of a marginal Fermi liquid, the resistivity is linear in temperature.
Charge transport in desolvated DNA
Wolter, Mario; Elstner, Marcus; Kubař, Tomáš
2013-09-01
The conductivity of DNA in molecular junctions is often probed experimentally under dry conditions, but it is unclear how much of the solvent remains attached to the DNA and how this impacts its structure, electronic states, and conductivity. Classical MD simulations show that DNA is unstable if the solvent is removed completely, while a micro-hydrated system with few water molecules shows similar charge transport properties as fully solvated DNA does. This surprising effect is analyzed in detail by mapping the density functional theory-based electronic structure to a tight-binding Hamiltonian, allowing for an estimate of conductivity of various DNA sequences with snapshot-averaged Landauer's approach. The characteristics of DNA charge transport turn out to be determined by the nearest hydration shell(s), and the removal of bulk solvent has little effect on the transport.
Charge transport in organic crystals
Ortmann, Frank
2009-07-01
The understanding of charge transport is one of the central goals in the research on semiconducting crystals. For organic crystals this is particularly complicated due to the strength of the electron-phonon interaction which requires the description of a seamless transition between the limiting cases of a coherent band-transport mechanism and incoherent hopping. In this thesis, charge transport phenomena in organic crystals are studied by theoretical means. A theory for charge transport in organic crystals is developed which covers the whole temperature range from low T, where it reproduces an expression from the Boltzmann equation for band transport, via elevated T, where it generalizes Holstein's small-polaron theory to finite bandwidths, up to high T, for which a temperature dependence equal to Marcus' electron-transfer theory is obtained. Thereby, coherent band transport and thermally induced hopping are treated on equal footing while simultaneously treating the electron-phonon interaction non-perturbatively. By avoiding the approximation of narrow polaron bands the theory allows for the description of large and small polarons and serves as a starting point for computational studies. The theoretical description is completed by using ab initio material parameters for the selected crystals under study. These material parameters are taken from density functional theory calculations for durene, naphthalene, and guanine crystals. Besides the analysis of the transport mechanism, special focus is put on the study of the relationship between mobility anisotropy and structure of the crystals. This study is supported by a 3D-visualization method for the transport channels in such crystals which has been derived in this thesis. (orig.)
Theory and design of charged particle beams
Reiser, Martin
1994-01-01
Although particle accelerators are the book's main thrust, it offers a broad synoptic description of beams which applies to a wide range of other devices such as low-energy focusing and transport systems and high-power microwave sources. Develops material from first principles, basic equations and theorems in a systematic way. Assumptions and approximations are clearly indicated. Discusses underlying physics and validity of theoretical relationships, design formulas and scaling laws. Features a significant amount of recent work including image effects and the Boltzmann line charge density prof
Supplementary kinetic constants of charged particles
Ribaric, Marijan; Sustersic, Luka
2006-01-01
We put forward: (A) An improved description of classical, kinetic properties of a charged pointlike physical particle that consists, in addition to its mass and charge, also of the Eliezer and Bhabha kinetic constants; and (B) a proposal to evaluate these kinetic constants by considering the trajectories of charged particles in an acccelerator.
Spinning charged test particles and Cosmic Censorship
The authors consider spinning charged test particles in the gravitational field of a rotating charged black hole, and it is shown that the hole cannot be destroyed, according to the Cosmic Censorship hypothesis. (Auth.)
Mechanisms for DNA Charge Transport
Genereux, Joseph C.; Barton, Jacqueline K.
2010-01-01
DNA charge transport (CT) chemistry has received considerable attention by scientific researchers over the past 15 years since our first provocative publication on long range CT in a DNA assembly.1,2 This interest, shared by physicists, chemists and biologists, reflects the potential of DNA CT to provide a sensitive route for signaling, whether in the construction of nanoscale biosensors or as an enzymatic tool to detect damage in the genome. Research into DNA CT chemistry began as a quest to...
Tattersall, W J; Boyle, G J; White, R D
2015-01-01
We generalize a simple Monte Carlo (MC) model for dilute gases to consider the transport behavior of positrons and electrons in Percus-Yevick model liquids under highly non-equilibrium conditions, accounting rigorously for coherent scattering processes. The procedure extends an existing technique [Wojcik and Tachiya, Chem. Phys. Lett. 363, 3--4 (1992)], using the static structure factor to account for the altered anisotropy of coherent scattering in structured material. We identify the effects of the approximation used in the original method, and develop a modified method that does not require that approximation. We also present an enhanced MC technique that has been designed to improve the accuracy and flexibility of simulations in spatially-varying electric fields. All of the results are found to be in excellent agreement with an independent multi-term Boltzmann equation solution, providing benchmarks for future transport models in liquids and structured systems.
Charge of dust particles in a particle chain
Yousefi, Razieh; Matthews, Lorin Swint; Hyde, Truell W
2016-01-01
Charged dust particles form structures which are extended in the vertical direction in the electrode sheath of a rf discharge when confined within a glass box. The charge on each particle as a function of height varies due to the changing plasma conditions and the wakefield of upstream particles. Here an analysis of the equilibrium state of chains of varying number of particles is analyzed to determine the charge on each particle within a vertically extended chain as well as the magnitude of the positive wakefield charge.
Worldline deviations of charged spinning particles
Heydari-Fard, M. [Department of Physics, Shahid Beheshti University, Evin, 19839 Tehran (Iran, Islamic Republic of); Mohseni, M. [Physics Department, Payame Noor University, 19395-4697 Tehran (Iran, Islamic Republic of)]. E-mail: m-mohseni@pnu.ac.ir; Sepangi, H.R. [Department of Physics, Shahid Beheshti University, Evin, 19839 Tehran (Iran, Islamic Republic of); Institute for Studies in Theoretical Physics and Mathematics, Tehran (Iran, Islamic Republic of)
2005-10-20
The geodesic deviation equation is generalized to worldline deviation equations describing the relative accelerations of charged spinning particles in the framework of Dixon-Souriau equations of motion.
Worldline deviations of charged spinning particles
Heydari-Fard, M; Sepangi, H R
2005-01-01
The geodesic deviation equation is generalized to worldline deviation equations describing the relative accelerations of charged spinning particles in the framework of Dixon-Souriau equations of motion.
Charge fluctuations in nonlinear heat transport
Gergs, Niklas M.; Hörig, Christoph B. M.; Wegewijs, Maarten R.; Schuricht, Dirk
2015-01-01
We show that charge fluctuation processes are crucial for the nonlinear heat conductance through an interacting nanostructure, even far from a resonance. The often made assumption that off-resonant transport proceeds only by virtual occupation of charge states, underlying exchange-scattering models of transport, can fail dramatically for heat transport as compared to charge transport. This indicates that nonlinear heat transport spectroscopy may be a very promising experimental tool, in parti...
Delay Equation for Charged Brown Particle
Vlasov, Alexander A.
2001-01-01
In previous work (physics/0004026) was shown, with the help of numerical calculations, that the effective Brown temperature for charged particle is lower than that for particle without charge. Here we derive this result without numerical calculations, integrating the delay equation analytically, as for zero, so for nonzero viscosity.
Beam transport and space charge compensation strategies (invited)
Meusel, O., E-mail: o.meusel@iap.uni-frankfurt.de; Droba, M.; Noll, D.; Schulte, K.; Schneider, P. P.; Wiesner, C. [IAP, Goethe University Frankfurt, Frankfurt D-60438 (Germany)
2016-02-15
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.
Beam transport and space charge compensation strategies (invited).
Meusel, O; Droba, M; Noll, D; Schulte, K; Schneider, P P; Wiesner, C
2016-02-01
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed. PMID:26932109
Beam transport and space charge compensation strategies (invited)
The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree of space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed
Charge transport in disordered materials
Gagorik, Adam Gerald
This thesis is focused on on using Monte Carlo simulation to extract device relevant properties, such as the current voltage behavior of transistors and the efficiency of photovoltaics, from the hopping transport of molecules. Specifically, simulation is used to study organic field-effect transistors (OFETs) and organic photo-voltaics (OPVs). For OFETs, the current was found to decrease with increasing concentration of traps and barriers in the system. As the barrier/trap concentration approaches 100%, the current recovers as carrier begin to travel through the manifold of connected trap states. Coulomb interactions between like charges are found to play a role in removing carriers from trap states. The equilibrium current in OFETs was found to be independent of charge injection method, however, the finite size of devices leads to an oscillatory current. Fourier transforms of the electrical current show peaks that vary non-linearly with device length, while being independent of device width. This has implications for the mobility of carriers in finite sized devices. Lastly, the presence of defects and high barriers (> 0.4 eV) was found to produce negative differential resistance in the saturation region of OFET curves, unlike traps. While defects and barriers prohibit carriers from reaching the drain at high voltages, the repulsive interaction between like charged carriers pushes charges around the defects. For OPVs, the effects of device morphology and charge delocalization were studied. Fill factors increased with domain size in monolayer isotropic morphologies, but decreased for band morphologies. In single-phase systems without Coulomb interactions, astonishingly high fill factors (. 70%) were found. In multilayer OPVs,a complex interplay of domain size, connectivity, tortuosity, interface trapping, and delocalization determined efficiency.
Scintillation Detectors for Charged Particles and Photons
Lecoq, P
2011-01-01
Scintillation Detectors for Charged Particles and Photons in 'Charged Particle Detectors - Particle Detectors and Detector Systems', part of 'Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms: Numerical Data and Functional Relationships in Science and Technology, Volume 21B1: Detectors for Particles and Radiation. Part 1: Principles and Methods'. This document is part of Part 1 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Subsection '3.1.1 Scintillation Detectors for Charged Particles and Photons' of Section '3.1 Charged Particle Detectors' of Chapter '3 Particle Detectors and Detector Systems' with the content: 3.1.1 Scintillation Detectors for Charged Particles and Photons 3.1.1.1 Basic detector principles and scintillator requirements 3.1.1.1.1 Interaction of ionizing radiation with scintillator material 3.1.1.1.2 Important scint...
Charged-particle activation analysis
The paper discusses the methodology and application of nuclear activation with ion beams (19 via 16O(3He,p)18F, 12C(3He,α)11C and 14N(p,α)11C respectively. Recently, triton activation has been shown to be inherently still superior to 3He activation for the determination of oxygen [16O(3H,n)18F]. Lithium, boron, carbon and sulphur can be detected rapidly, nondestructively and with high sensitivity (approximately 0.25ppm for Li and B) via ''quasi-prompt'' activation based on the detection of short-lived, high-energy beta emitters (10ms1H(7Li,n)7Be for example. Nondestructive multielement analysis: Proton activation has the inherent potential for meeting requirements of broad elemental coverage, sensitivity (ppm and sub-ppm range) and selectivity. Up to 30 elements have been determined in Al, Co, Ag, Nb, Rh, Ta and biological samples, using 12-MeV proton activation followed by gamma-ray spectrometry. These capabilities are further enhanced with the counting of X-ray emitters, 28 elements (269) and accuracy using proton activation. 204Pb/206Pb ratios can also be determined with a relative precision of a few per cent. Although charged-particle activation analysis is a well-established trace analysis technique, broad potential capabilities remain to be explored, e.g. those arising from ultrashort-lived nuclides, heavy ion interactions and the combination of delayed and prompt methods. (author)
Coagulation of charged particles in dust plasma
One studied peculiarities of behaviour of small particles in dust plasma resulted on the one hand, from suppression of coagulation due to monopolar charging within the range of particle dimensions under the Debye radius of shielding and, on the other hand, from leveling of this case for particles of large dimensions. On the basis of similarity ratios one determined the range of parameters making linear approximation of particle charge dependence on their dimension true. In terms of the modified classical theory of coagulation in diffusion approximation one studied certain anomalies of behavior of dimension distribution of particles. It is determined that in contrast to the ordinary aerosol in dust plasma as time passes one may reduce dispersion of distribution and average dimensions of particles. For the first time one demonstrates the possibility to realize long-lived quasiliquid state of dust plasma associated with the anomalous behaviour of distribution function of coagulating charged particles according to dimensions
Measuring Charge Transport in an Amorphous Semiconductor Using Charge Sensing
Maclean, K; Mentzel, T. S.; Kastner, M. A.
2009-01-01
We measure charge transport in hydrogenated amorphous silicon (a-Si:H) using a nanometer scale silicon MOSFET as a charge sensor. This charge detection technique makes possible the measurement of extremely large resistances. At high temperatures, where the a-Si:H resistance is not too large, the charge detection measurement agrees with a direct measurement of current. The device geometry allows us to probe both the field effect and dispersive transport in the a-Si:H using charge sensing and t...
Charged Particle Diffusion in Isotropic Random Static Magnetic Fields
Subedi, P.; Sonsrettee, W.; Matthaeus, W. H.; Ruffolo, D. J.; Wan, M.; Montgomery, D.
2013-12-01
Study of the transport and diffusion of charged particles in a turbulent magnetic field remains a subject of considerable interest. Research has most frequently concentrated on determining the diffusion coefficient in the presence of a mean magnetic field. Here we consider Diffusion of charged particles in fully three dimensional statistically isotropic magnetic field turbulence with no mean field which is pertinent to many astrophysical situations. We classify different regions of particle energy depending upon the ratio of Larmor radius of the charged particle to the characteristic outer length scale of turbulence. We propose three different theoretical models to calculate the diffusion coefficient each applicable to a distinct range of particle energies. The theoretical results are compared with those from computer simulations, showing very good agreement.
Charge Transfer and Charge Transport on the Double Helix
N. P. Armitage; Briman, M.; Gruner, G.
2003-01-01
We present a short review of various experiments that measure charge transfer and charge transport in DNA. Some general comments are made on the possible connection between 'chemistry-style' charge transfer experiments that probe fluorescence quenching and remote oxidative damage and 'physics-style' measurements that measure transport properties as defined typically in the solid-state. We then describe measurements performed by our group on the millimeter wave response of DNA. By measuring ov...
Sources for charged particles; Les sources de particules chargees
Arianer, J.
1997-09-01
This document is a basic course on charged particle sources for post-graduate students and thematic schools on large facilities and accelerator physics. A simple but precise description of the creation and the emission of charged particles is presented. This course relies on every year upgraded reference documents. Following relevant topics are considered: electronic emission processes, technological and practical considerations on electron guns, positron sources, production of neutral atoms, ionization, plasma and discharge, different types of positive and negative ion sources, polarized particle sources, materials for the construction of ion sources, low energy beam production and transport. (N.T.).
Weak charges of charmed particles
The matrix elements between the lowest states of the ΔC=1 weak charges are evaluated including the effect of SU4 breaking. The charges are obtained from the corresponding generators of the classification group by a unitary transformation U, which is factorized as the product of operators acting on a single quark: the breaking is naturally introduced by having different mixing parameters for the different quarks
Robust statistical reconstruction for charged particle tomography
Schultz, Larry Joe; Klimenko, Alexei Vasilievich; Fraser, Andrew Mcleod; Morris, Christopher; Orum, John Christopher; Borozdin, Konstantin N; Sossong, Michael James; Hengartner, Nicolas W
2013-10-08
Systems and methods for charged particle detection including statistical reconstruction of object volume scattering density profiles from charged particle tomographic data to determine the probability distribution of charged particle scattering using a statistical multiple scattering model and determine a substantially maximum likelihood estimate of object volume scattering density using expectation maximization (ML/EM) algorithm to reconstruct the object volume scattering density. The presence of and/or type of object occupying the volume of interest can be identified from the reconstructed volume scattering density profile. The charged particle tomographic data can be cosmic ray muon tomographic data from a muon tracker for scanning packages, containers, vehicles or cargo. The method can be implemented using a computer program which is executable on a computer.
New Charged Particles from Higgs Couplings
Cohen, Andrew G
2012-01-01
The recently reported observation of a new particle with mass about 125 GeV and couplings generally resembling those of the Standard Model Higgs boson provides a potential probe of the physics of electroweak symmetry breaking. Although the current data only provides hints, we suggest a particular combination of Higgs couplings as an assay for new charged particles connected with electroweak symmetry breaking, and construct a simple model with charge 5/3 quarks as a demonstration of its use.
M. V. Rodrigues
2006-03-01
Full Text Available This work gives sequence to the study on the measurement of the electrostatic charges in aerosols. The particle charge classifier developed for this purpose and presented in the previous paper (Marra and Coury, 2000 has been used here to measure the particle charge distribution of a number of different aerosols. The charges acquired by the particles were naturally derived from the aerosol generation procedure itself. Two types of aerosol generators were used: the vibrating orifice generator and turntable Venturi plate generator. In the vibrating orifice generator, mono-dispersed particles were generated by a solution of water/ethanol/methylene blue, while in the rotating plate generator, six different materials were utilized. The results showed no clear dependence between electric charge and particle diameter for the mono-dispersed aerosol. However, for the poly-dispersed aerosols, a linear dependence between particle size and charge could be noticed.
Charge transfer and transport in DNA
Jortner, Joshua; Bixon, Mordechai; Langenbacher, Thomas; Michel-Beyerle, Maria E.
1998-01-01
We explore charge migration in DNA, advancing two distinct mechanisms of charge separation in a donor (d)–bridge ({Bj})–acceptor (a) system, where {Bj} = B1,B2, … , BN are the N-specific adjacent bases of B-DNA: (i) two-center unistep superexchange induced charge transfer, d*{Bj}a → d∓{Bj}a±, and (ii) multistep charge transport involves charge injection from d* (or d+) to {Bj}, charge hopping within {Bj}, and charge trapping by a. For off-resonance coupling, mechanism i prevails with the char...
Particles with non abelian charges
Bastianelli, Fiorenzo; Corradini, Olindo; Latini, Emanuele
2013-01-01
Efficient methods for describing non abelian charges in worldline approaches to QFT are useful to simplify calculations and address structural properties, as for example color/kinematics relations. Here we analyze in detail a method for treating arbitrary non abelian charges. We use Grassmann variables to take into account color degrees of freedom, which however are known to produce reducible representations of the color group. Then we couple them to a U(1) gauge field defined on the worldline, together with a Chern-Simons term, to achieve projection on an irreducible representation. Upon gauge fixing there remains a modulus, an angle parametrizing the U(1) Wilson loop, whose dependence is taken into account exactly in the propagator of the Grassmann variables. We test the method in simple examples, the scalar and spin 1/2 contribution to the gluon self energy, and suggest that it might simplify the analysis of more involved amplitudes.
Charged particle concepts for fog dispersion
Frost, W.; Collins, F. G.; Koepf, D.
1981-01-01
Charged particle techniques hold promise for dispersing warm fog in the terminal area of commercial airports. This report focuses on features of the charged particle technique which require further study. The basic physical principles of the technique and the major verification experiments carried out in the past are described. The fundamentals of the nozzle operation are given. The nozzle characteristics and the theory of particle charging in the nozzle are discussed, including information from extensive literature on electrostatic precipitation relative to environmental pollution control and a description of some preliminary reported analyses on the jet characteristics and interaction with neighboring jets. The equation governing the transfer of water substances and of electrical charge is given together with a brief description of several semi-empirical, mathematical expressions necessary for the governing equations. The necessary ingredients of a field experiment to verify the system once a prototype is built are described.
Towards a microscopic theory of particle charging
Bronold, Franz X; Kersten, H; Deutsch, H
2009-01-01
We recently questioned the treatment of a dust particle as a perfect absorber for electrons and ions and proposed a surface model for the charge of a dust particle in a quiescent plasma which combines the microscopic physics at the grain boundary (sticking into and desorption from external surface states) with the macrophysics of the discharge (plasma collection fluxes). Within this model the charge and partial screening of the particle can be calculated without relying on the condition that the total electron collection flux balances on the grain surface the total ion collection flux. Grain charges obtained from our approach compared favorably with experimental data. The purpose of this paper is to describe our model in more detail, in particular, the hypotheses on which it is built, contrast it with the standard charging models based on flux balancing on the grain surface, and to analyze additional experimental data.
Fractionally charged particles in cosmic rays
Bashindzhagyan, George
2016-01-01
The results of many experiments on a search of fractionally charged particles in cosmic rays have been reviewed. The registered by ATIC and PAMELA experiments change of the proton energy spectrum at about 250 GeV can be explained if fractionally charged particles with another energy spectrum slope actually mixed with protons but cannot be separated because of a strong dE/dx fluctuations. The performed simulations show that multilayer detectors can seriously help in such separation. In the Aragats experiment performed using multilayer proportional counter combined with hadron calorimeter a group of 4e/3 like events with unexpectedly high average energy has been registered. It could be explained by their different from regular hadrons energy spectrum. The ATIC experiment ionization spectrum in single charged particle area has been examined. An interesting bump in 2e/3 charge region was observed. The events in the bump have very different from regular protons angular distribution.
Electro-optical detection of charged particles
Semertzidis, Y K; Kowalski, L A; Kraus, D E; Larsen, R; Lazarus, D M; Magurno, B; Nikas, D; Ozben, C; Srinivasan-Rao, T; Tsang, Thomas
2000-01-01
We have made the first observation of a charged particle beam by means of its electro-optical effect on the polarization of laser light in a LiNbO sub 3 crystal. The modulation of the laser light during the passage of a pulsed electron beam was observed using a fast photodiode and a digital oscilloscope. The fastest rise time measured, 120 ps, was obtained in the single shot mode and was limited by the bandwidth of the oscilloscope and the associated electronics. This technology holds good for detectors of greatly improved spatial and temporal resolution for single relativistic charged particles as well as particle beams.
Cooperative Transport of Brownian Particles
Derenyi, Imre; Vicsek, Tamas
1998-01-01
We consider the collective motion of finite-sized, overdamped Brownian particles (e.g., motor proteins) in a periodic potential. Simulations of our model have revealed a number of novel cooperative transport phenomena, including (i) the reversal of direction of the net current as the particle density is increased and (ii) a very strong and complex dependence of the average velocity on both the size and the average distance of the particles.
Why do particle clouds generate electric charges?
Pähtz, T.; Herrmann, H. J.; Shinbrot, T.
2010-05-01
Grains in desert sandstorms spontaneously generate strong electrical charges; likewise volcanic dust plumes produce spectacular lightning displays. Charged particle clouds also cause devastating explosions in food, drug and coal processing industries. Despite the wide-ranging importance of granular charging in both nature and industry, even the simplest aspects of its causes remain elusive, because it is difficult to understand how inert grains in contact with little more than other inert grains can generate the large charges observed. Here, we present a simple yet predictive explanation for the charging of granular materials in collisional flows. We argue from very basic considerations that charge transfer can be expected in collisions of identical dielectric grains in the presence of an electric field, and we confirm the model's predictions using discrete-element simulations and a tabletop granular experiment.
Search milli-charged particles at SLAC
Langeveld, W.G.J. [Stanford Univ., CA (United States)
1997-01-01
Particles with electric charge q {triple_bond} Qe {le} 10{sup -3} e and masses in the range 1-1000 MeV/c{sup 2} are not excluded by present experiments or by astrophysical or cosmological arguments. A beam dump experiment uniquely suited to the detection of such {open_quotes}milli-charged{close_quotes} particles has been carried out at SLAC, utilizing the short-duration pulses of the SLC electron beam to establish a tight coincidence window for the signal. The detector, a large scintillation counter sensitive to very small energy depositions, provided much greater sensitivity than previous searches. Analysis of the data leads to the exclusion of a substantial portion of the charge-mass plane. In this report, a preliminary mass-dependent upper limit is presented for the charge of milli-charged particles, ranging from Q = 1.7 x 10{sup -5} at milli-charged particle mass 0.1 MeV/c{sup 2} to Q = 9.5 x 10{sup -4} at 100 MeV/c{sup 2}.
Graphical abstract: Highlights: → The electron lifetime increases with increasing the nanotube concentration. → The electron transport time is shortest at 10 wt% TiO2 nanotubes. → The electron collection efficiency achieves maxima at 10 wt% nanotubes. → The energy conversion efficiency obtains the highest value at 10 wt% nanotubes. - Abstract: In this paper, anodic TiO2 nanotubes are blended into the TiO2 mesoporous films based on P25 nanoparticles to assemble a list of dye-sensitized solar cells (DSSCs) with different nanotube concentrations. The electron properties of transport and recombination in the fabricated DSSCs are studied by using electrochemical impedance spectroscopy and the open-circuit voltage decay technique under AM 1.5 illumination. Results indicate that the electron lifetime increases with increasing the concentration of the anodic TiO2 nanotubes, the electron transport time at a blending level of 10 wt% TiO2 nanotubes is short as compared to that at 0 wt%, and above 10 wt%, the electron transport time has a trend of becoming large. Due to the combining effects of the electron transport and recombination, the electron collecting efficiency and the electron diffusion length obtain maxima at a blending level of 10 wt% nanotubes, which results in a highest short circuit current and a maximum energy conversion efficiency at this point in the DSSCs. This study gives a clear explanation for the performance enhancement of TiO2 particle-based DSSCs at a blending level of 10 wt% anodic TiO2 nanotubes and for the performance decrease at a blending level over 10 wt% anodic TiO2 nanotubes from the angle of the electron transport and recombination. This study also supplies a feasible and easy way to improve the performance of particle-based DSSCs by restraining electron recombination and accelerating electron transportation.
Simulation of non-charged particles
This paper presents the method used to simulate the transport of neutral particles by using a Monte Carlo method with accelerating techniques of convergence based on the importance function by the method of first collision probabilities
Bibliography of integral charged particle nuclear data
This publication is the second supplement to the archival edition of the National Nuclear Data Center's charged-particle bibliography. This supplement contains citations to all references scanned since March 15, 1981, and all corrections and additions to previous citations, and indexes all data received in the international exchanged format (EXFOR). The primary goal of the bibliography has been to satisfy the need expressed by the Nuclear Reaction Data Center Network for a concise and comprehensive bibliography of integral charged-particle cross section data and to provide an index of data exchanged among the members. In 1980, coverage was expanded to include differential data relevant to charged-particle-induced neutron-source reactions
Integral charged particle nuclear data bibliography
Holden, N.E.; Ramavataram, S.
1989-12-01
This publication is the annual supplement to the first edition published in 1984. The primary goal of this publication has been to satisfy the need expressed by the Nuclear Reaction Data Center Network for a concise and comprehensive bibliography of integral charged--particle cross section data. Included in this paper is a partial list of other bibliographies relevant to charged-particle-induced reaction data and a source list of nuclear data bibliographies, complications, and cumulative, earlier versions are also shown in the tables. This publication makes use of a modification to the database of the Nuclear Structure References (NSR) file. This modification allows the retrieval of integral charged particle nuclear data entries from the NSR file. In recent years, the presentation of various sections was changed, as a result of users' suggestions. The authors continue to welcome users' comments.
Integral charged particle nuclear data bibliography
This publication is the annual supplement to the first edition published in 1984. The primary goal of this publication has been to satisfy the need expressed by the Nuclear Reaction Data Center Network for a concise and comprehensive bibliography of integral charged--particle cross section data. Included in this paper is a partial list of other bibliographies relevant to charged-particle-induced reaction data and a source list of nuclear data bibliographies, complications, and cumulative, earlier versions are also shown in the tables. This publication makes use of a modification to the database of the Nuclear Structure References (NSR) file. This modification allows the retrieval of integral charged particle nuclear data entries from the NSR file. In recent years, the presentation of various sections was changed, as a result of users' suggestions. The authors continue to welcome users' comments
Position sensitive detector of magnetically charged particles
Two variants of coordinate detectors of magnetically charged paticles based on the utilization of transducers with Josephson transitions are proposed. The system of data acquisition and processing is built up in the CAMAC standard. The helium cryostat diagram is presented. The detector resolution time and dead time constitute 1 μs. Methods of detection of magnetically charged particles used in the above detectors are expected to be more effective, as compared to ionization method and other indirect methods
Fog camera to visualize ionizing charged particles
The human being can not perceive the different types of ionizing radiation, natural or artificial, present in the nature, for what appropriate detection systems have been developed according to the sensibility to certain radiation type and certain energy type. The objective of this work was to build a fog camera to visualize the traces, and to identify the trajectories, produced by charged particles with high energy, coming mainly of the cosmic rays. The origin of the cosmic rays comes from the solar radiation generated by solar eruptions where the protons compose most of this radiation. It also comes, of the galactic radiation which is composed mainly of charged particles and gamma rays that comes from outside of the solar system. These radiation types have energy time millions higher that those detected in the earth surface, being more important as the height on the sea level increases. These particles in their interaction produce secondary particles that are detectable by means of this cameras type. The camera operates by means of a saturated atmosphere of alcohol vapor. In the moment in that a charged particle crosses the cold area of the atmosphere, the medium is ionized and the particle acts like a condensation nucleus of the alcohol vapor, leaving a visible trace of its trajectory. The built camera was very stable, allowing the detection in continuous form and the observation of diverse events. (Author)
Control microprocessor system for charge particle channeling
Control microprocessor systems are widely applied not only in designing industrial robots but in providing functioning of different experimental plants. The experiment control system for charge particle channeling has been considered in the paper. Flexibility, relatively low cost and high reliability are advantages of these systems
Studying Charged Particle Optics: An Undergraduate Course
Ovalle, V.; Otomar, D. R.; Pereira, J. M.; Ferreira, N.; Pinho, R. R.; Santos A. C. F.
2008-01-01
This paper describes some computer-based activities to bring the study of charged particle optics to undergraduate students, to be performed as a part of a one-semester accelerator-based experimental course. The computational simulations were carried out using the commercially available SIMION program. The performance parameters, such as the focal…
Treatment of cancer with heavy charged particles
The goals of the clinical helium and heavy charged particle radiotherapy trial are: (1) to evaluate the potential of improved dose localization as exemplified by helium-ion irradiation where little, if any, biological advantage is expected; and (2) to evaluate the combined potential of improved dose localization and increased biological effect available with heavier ions such as carbon, neon, silicon, and argon ions
Bmad: A relativistic charged particle simulation library
Bmad is a subroutine library for simulating relativistic charged particle beams in high-energy accelerators and storage rings. Bmad can be used to study both single and multi-particle beam dynamics using routines to track both particles and macroparticles. Bmad has various tracking algorithms including Runge-Kutta and symplectic (Lie algebraic) integration. Various effects such as wakefields, and radiation excitation and damping can be simulated. Bmad has been developed in a modular, object-oriented fashion to maximize flexibility. Interface routines allow Bmad to be called from C/C++ as well as Fortran programs. Bmad is well documented. Every routine is individually annotated, and there is an extensive manual
Charged Particles' Tunneling from Noncommutative Charged Black Hole
Mehdipour, S Hamid
2010-01-01
We apply the tunneling process of charged massive particles through the quantum horizon of a Reissner-Nordstr\\"om black hole in a new noncommutative gravity scenario. In this model, the tunneling amplitude on account of noncommutativity influences in the context of coordinate coherent states is modified. Our calculation points out that the emission rate satisfies the first law of black hole thermodynamics and is consistent with an underlying unitary theory.
Charged particles' tunneling from a noncommutative charged black hole
Mehdipour, S. Hamid
2010-01-01
We apply the tunneling process of charged massive particles through the quantum horizon of a Reissner-Nordstrom black hole in a new noncommutative gravity scenario. In this model, the tunneling amplitude on account of noncommutativity influences in the context of coordinate coherent states is modified. Our calculation points out that the emission rate satisfies the first law of black hole thermodynamics and is consistent with an underlying unitary theory.
Tumor therapy with heavy charged particles
Blattmann, Hans
1999-11-01
Nuclear science has contributed significantly to the development of tumor therapy with heavy charged particles. Interest evolved for neutron therapies in the forties because of the increased radiobiological effectiveness (RBE) compared to photon irradiation. The development of more powerful proton and heavy ion accelerators with higher energies or higher intensities, made new particles for radiation therapy available. Pions, protons, light ions, from helium up to silicon were studied in view of precision dose delivery and increased RBE. Without the parallel development of new diagnostic techniques such as computer tomography (CT) and positron emission tomography (PET) the rapid development would not have been possible. Heavy-charged particle therapy has now come into a consolidation phase. Hospital-based facilities are built by industry, and research institutes focus on refinements in dose delivery and treatment planning, as well as systems for monitoring dose delivery and for dose distribution verification.
High-frequency charged particle accelerator
The device is refered to technical physics and may be used as a source of accelerated particles for irradiation of different objects in industry and agriculture. The device is aimed at increase of the power and enhancement of stability of the accelerator operation and decrease of its dimensions. High-frequency accelerator is composed of an accelerating cavity resonator a charged particle source and HF power supply. The aim is attained by the fact, that HF power source anode is made as one of coupling capasitor plates, the second plate of which is the nearest to anode HF power supply grid. The coupling capacitor plalte functional union with the HF power supply electrodes (anode and grid) reduces to spirious inductances of HF power supply circuit to minimum. Besides, the accelerator structure is simplified, as additional cooling system for the charged particle source is not necessary
Charge and spin transport in mesoscopic superconductors
M. J. Wolf
2014-02-01
Full Text Available Background: Non-equilibrium charge transport in superconductors has been investigated intensely in the 1970s and 1980s, mostly in the vicinity of the critical temperature. Much less attention has been paid to low temperatures and the role of the quasiparticle spin.Results: We report here on nonlocal transport in superconductor hybrid structures at very low temperatures. By comparing the nonlocal conductance obtained by using ferromagnetic and normal-metal detectors, we discriminate charge and spin degrees of freedom. We observe spin injection and long-range transport of pure, chargeless spin currents in the regime of large Zeeman splitting. We elucidate charge and spin transport by comparison to theoretical models.Conclusion: The observed long-range chargeless spin transport opens a new path to manipulate and utilize the quasiparticle spin in superconductor nanostructures.
At the present time a Monte Carlo transport computer code is being designed and implemented at Lawrence Livermore National Laboratory to include the transport of: neutrons, photons, electrons and light charged particles as well as the coupling between all species of particles, e.g., photon induced electron emission. Since this code is being designed to handle all particles this approach is called the ''All Particle Method''. The code is designed as a test bed code to include as many different methods as possible (e.g., electron single or multiple scattering) and will be data driven to minimize the number of methods and models ''hard wired'' into the code. This approach will allow changes in the Livermore nuclear and atomic data bases, used to described the interaction and production of particles, to be used to directly control the execution of the program. In addition this approach will allow the code to be used at various levels of complexity to balance computer running time against the accuracy requirements of specific applications. This paper describes the current design philosophy and status of the code. Since the treatment of neutrons and photons used by the All Particle Method code is more or less conventional, emphasis in this paper is placed on the treatment of electron, and to a lesser degree charged particle, transport. An example is presented in order to illustrate an application in which the ability to accurately transport electrons is important. 21 refs., 1 fig
Dust charging and transport on airless planetary bodies
Wang, X.; Schwan, J.; Hsu, H.-W.; Grün, E.; Horányi, M.
2016-06-01
We report on laboratory experiments to shed light on dust charging and transport that have been suggested to explain a variety of unusual phenomena on the surfaces of airless planetary bodies. We have recorded micron-sized insulating dust particles jumping to several centimeters high with an initial speed of ~0.6 m/s under ultraviolet illumination or exposure to plasmas, resulting in an equivalent height of ~0.11 m on the lunar surface that is comparable to the height of the so-called lunar horizon glow. Lofted large aggregates and surface mobilization are related to many space observations. We experimentally show that the emission and re-absorption of photoelectron and/or secondary electron at the walls of microcavities formed between neighboring dust particles below the surface are responsible for generating unexpectedly large negative charges and intense particle-particle repulsive forces to mobilize and lift off dust particles.
Acceleration of charged particles in laser beam
M.J. Małachowski
2009-12-01
Full Text Available Purpose: The aim of this paper was to find parameters of the laser and maser beams in numerical ways with additionally applied external static axial magnetic field which satisfies the proper conditions for charged particle acceleration.Design/methodology/approach: The set acceleration was designed in order to obtain the possible high kinetic energy of the charged particles in the controllable manner. This was achieved applying a circularly polarized high intensity laser beam and a static axial magnetic field, both acting on the particle during the proper period.Findings: The quantitative illustrations of the calculation results, in a graphical form enabled to discuss the impact of many parameters on the acceleration process of the electrons and protons. We have found the impact of the Doppler Effect on the acceleration process to be significant. Increase in laser or maser beam intensity results in particle’s energy increase and its trajectory dimension. However, increase in external magnetic field results in shrinking of the helical trajectories. It enables to keep the particle inside the laser beam.Research limitations/implications: Limits in the energy of accelerated particles arise from the limitsin up-to-date available laser beam energy and the beam diameters.Originality/value: The authors show the parameters of the circularly polarized laser beam which should be satisfied in order to obtain the desired energy of the accelerated particles. The influence of the magnetic field strength is also shown.
The formation of negatively charged particles in thermoemission plasmas
Vishnyakov, V. I.; Dragan, G. S.; Florko, A. V.
2008-01-01
The results of measuring the charges of the magnesium oxide particles formed near a block of metallic magnesium burning in air are presented. It has been found that, apart from positively charged magnesium oxide particles, there are negatively charged particles in the thermoemission plasma of the burning products. It has been shown that within the framework of the model of neutralizing charges, the oxide particles can acquire unlike charges in the thermoemission plasma. The calculations agree with the experimental data.
The formation of negatively charged particles in thermoemission plasmas
Vishnyakov, V. I., E-mail: pipeaes@te.net.ua; Dragan, G. S.; Florko, A. V. [Mechnikov Odessa National University (Ukraine)
2008-01-15
The results of measuring the charges of the magnesium oxide particles formed near a block of metallic magnesium burning in air are presented. It has been found that, apart from positively charged magnesium oxide particles, there are negatively charged particles in the thermoemission plasma of the burning products. It has been shown that within the framework of the model of neutralizing charges, the oxide particles can acquire unlike charges in the thermoemission plasma. The calculations agree with the experimental data.
The formation of negatively charged particles in thermoemission plasmas
The results of measuring the charges of the magnesium oxide particles formed near a block of metallic magnesium burning in air are presented. It has been found that, apart from positively charged magnesium oxide particles, there are negatively charged particles in the thermoemission plasma of the burning products. It has been shown that within the framework of the model of neutralizing charges, the oxide particles can acquire unlike charges in the thermoemission plasma. The calculations agree with the experimental data
Born expansions for charged particle scattering
High-order terms in Born expansions of scattering amplitudes in powers of charge are frequently divergent when long-range Coulomb interactions are present asymptotically. Expansions which are free from these logarithmic divergences have been constructed recently. This paper illustrates these expansions with the simplest example, namely the non-relativistic Rutherford scattering of two charged particles. This approach represents an adequate framework for the calculation of transition amplitudes and a comprehensive starting point for the development of consistent perturbation approximations in multi-channel descriptions of strongly interacting atomic systems
On the Langevin approach to particle transport
In the Langevin description of Brownian motion, the action of the surrounding medium upon the Brownian particle is split up into a systematic friction force of Stokes type and a randomly fluctuating force, alternatively termed noise. That simple description accounts for several basic features of particle transport in a medium, making it attractive to teach at the undergraduate level, but its range of applicability is limited. The limitation is illustrated here by showing that the Langevin description fails to account realistically for the transport of a charged particle in a medium under crossed electric and magnetic fields and the ensuing Hall effect. That particular failure is rooted in the concept of the friction force rather than in the accompanying random force. It is then shown that the framework of kinetic theory offers a better account of the Hall effect. It is concluded that the Langevin description is nothing but an extension of Drude's transport model subsuming diffusion, and so it inherits basic limitations from that model. This paper thus describes the interrelationship of the Langevin approach, the Drude model and kinetic theory, in a specific transport problem of physical interest
Method for charged particle beam acceleration
The method of charged particle beam acceleration based on its resonance interaction with electromagnetic field of travelling wave is suggested. The electron beam is injected into waveguide in which longitudinal magnetic field and electromagnetic wave are excited. With the purpose of reducing HF-power losses in the waveguide walls, the azimuthal particle motion is synchronized with azimuthal change of longitudinal component of electric field of the accelerating electromagnetic wave. The suggested method permits to increase the efficiency and shunting resistance of the accelerating waveguide by reducing its boundary surface
Collective aspects of charged particle track structure
A plasmon generated by a swift charged particle constitutes a coherent excitation about the particle track. We discuss the representation of collective modes in impact parameter space when created by a swift ion or a fast electron, and the decay of these modes into localized excitations. Several alternative spatial representations are considered. We show that the high spatial resolution found in secondary electron emission measurements with scanning electron microscopy is consistent with the existence of the plasmon as an intermediary between the fast incident electron and the measured secondary electrons. 24 refs., 6 figs
Charge State Model of Solar Energetic Particles
Del Peral, L.; Pérez-Peraza, J. A.; Rodríguez Frías, M. D.
2013-05-01
Charge states of heavy ions in Solar Energetic Particle (SEP) events observed at the Earth's neighborhood with experiments on board satellites give us information about physical properties of plasma where acceleration occurs. SEP detection is performed near the Earth, therefore not only physical condition of the plasma source of accelerated particles have to be taken into account. We have developed a charge state model in order to explain the evolution of particle charge states under solar acceleration. Charge-interchange processes between the accelerated ions and the plasma matter in the acceleration region are considered on basis of electron loss and capture cross sections at high energies. We have applied the model to observational data from satellites measuring charge states of SEPs. In contrast with other models that use ionization and recombination cross-sections that require application of thermal equilibrium, our model assumes that the acceleration is so fast that thermal equilibrium can not be applied to the change interchange processes. Therefore we employ in our model high energy cross-sections for electron capture and loss, since the population which is being accelerated acquires a non-thermal spectrum. We have developed temperature dependent cross-sections. Acceleration begins from a thermal distribution. As soon as the particles increase their energy by the acceleration process, they acquire an energy spectrum which differs from the Maxwellian thermal one while interacting with the background thermal matter. Figure 1 presents the results of our model that fit experimental charge states of Fe ions from two impulsive SEP events detected by the SEPICA satellite in July 1999. We obtain good fitting for source temperature of 1.8 \\cdot 106 K and density of 5\\cdot108 cm-3 and acceleration efficiency of 1.8\\cdot 10-2 s-1 for the July 20th 1999 event and 3.3\\cdot 10-2 s-1 for the July 3rd 1999. Good concordance between experimental data and our model have
High-LET charged particle radiotherapy
The Department of Radiation Oncology at UCSF Medical Center and the Radiation Oncology Department at UC Lawrence Berkeley Laboratory have been evaluating the use of high LET charged particle radiotherapy in a Phase 1--2 research trial ongoing since 1979. In this clinical trail, 239 patients have received at least 10 Gy (physical) minimum tumor dose with neon ions, meaning that at least one-half of their total treatment was given with high-LET charged particle therapy. Ninety-one patients received all of their therapy with neon ions. Of the 239 patients irradiated, target sites included lesions in the skin, subcutaneous tissues, head and neck such as paranasal sinuses, nasopharynx and salivary glands (major and minor), skull base and juxtaspinal area, GI tract including esophagus, pancreas and biliary tract, prostate, lung, soft tissue and bone. Analysis of these patients has been carried out with a minimum followup period of 2 years
Charge transport in conducting polymers
Polymers with metal-like electrical conductivity are presented as novel materials. After a short discussion of the present situation of technical applications experimental data on the electrical conductivity and its temperature and frequency dependence are reviewed. These data are discussed within the framework of a model involving fluctuation-induced tunneling between marcroscopic inhomogeneities and energy dependent hopping of charge carriers between localized states on a microscopic level. Pulsed photoconductivity measurements indicate that also in photoconductivity a hopping mechanism is dominant and solitary wave motion of conjugational defects escapes observation. (orig.)
Relativity primer for particle transport. A LASL monograph. [Monograph
Everett, C.J.; Cashwell, E.D.
1979-04-01
The basic principles of special relativity involved in Monte Carlo transport problems are developed with emphasis on the possible transmutations of particles, and on computational methods. Charged particle ballistics and polarized scattering are included, as well as a discussion of colliding beams.
Charge carrier transport in liquid crystals
The materials exhibiting charge carrier mobility ranging from 10−3 to 0.1 cm2/Vs, i.e., between those of amorphous and crystalline materials, had been missing before the 1990s when the electronic conduction in liquid crystals was discovered. Since then, various liquid crystalline materials including discotic and calamitic liquid crystals have been studied in order to clarify their charge carrier transport properties in liquid crystalline mesophases. In this article, the historical background of the discovery of electronic conduction in liquid crystals, intrinsic and extrinsic conductions, unique properties of the charge carrier transport, the effect of molecular alignment on it, and the conduction mechanism in liquid crystalline mesophases are shortly described on the basis of the experimental and theoretical studies accumulated in these two decades, noting that the missing materials were liquid crystals. - Highlights: • Liquid crystals exhibit charge mobility ranging from 10–3 to 0.1 cm2/Vs. • Electronic (intrinsic) and ionic (extrinsic) conductions in liquid crystals • Unique charge carrier transport properties in liquid crystals • Effect of molecular alignment in mesophases on charge carrier transport • Conduction mechanism in smectic liquid crystals
Geometrical charged-particle optics. 2. ed.
Rose, Harald [Technische Univ. Darmstadt (Germany). Inst. fuer Angewandte Physik
2013-03-01
Provides a unique theoretical treatment of charged-particle optics. Displays novel unpublished results on several topics. Provides insight into the properties of charged-particle devices. Treats wave optical properties of the electron. Presents the resolution limit of electron microscopes and novel theoretical treatment of the Stern-Gerlach effect. This second edition is an extended version of the first edition of Geometrical Charged-Particle Optics. The updated reference monograph is intended as a guide for researchers and graduate students who are seeking a comprehensive treatment of the design of instruments and beam-guiding systems of charged particles and their propagation in electromagnetic fields. Wave aspects are included in this edition for explaining electron holography, the Aharanov-Bohm effect and the resolution of electron microscopes limited by diffraction. Several methods for calculating the electromagnetic field are presented and procedures are outlined for calculating the properties of systems with arbitrarily curved axis. Detailed methods are presented for designing and optimizing special components such as aberration correctors, spectrometers, energy filters monochromators, ion traps, electron mirrors and cathode lenses. In particular, the optics of rotationally symmetric lenses, quadrupoles, and systems composed of these elements are discussed extensively. Beam properties such as emittance, brightness, transmissivity and the formation of caustics are outlined. Relativistic motion and spin precession of the electron are treated in a covariant way by introducing the Lorentz-invariant universal time and by extending Hamilton's principle from three to four spatial dimensions where the laboratory time is considered as the fourth pseudo-spatial coordinate. Using this procedure and introducing the self action of the electron, its accompanying electromagnetic field and its radiation field are calculated for arbitrary motion. In addition, the Stern
Automated control system in charged particle accelerators
A general approach to the design of automated radiation safety systems at charged particle accelerators is described. Parameters of high-energy electron accelerators of the Kharkov Physics and Engineering Institute are presented. Characteristics of the surrounding radiation fields are given. Ionizing radiation transducers which can be used in automated systems are considered. Local radiation monitoring station based on the LUE-2000 accelerator of the institute is described. 9 refs.; 4 figs.; 1 tab
Controlling Charged Particles with Inhomogeneous Electrostatic Fields
Herrero, Federico A. (Inventor)
2016-01-01
An energy analyzer for a charged-particle spectrometer may include a top deflection plate and a bottom deflection plate. The top and bottom deflection plates may be non-symmetric and configured to generate an inhomogeneous electrostatic field when a voltage is applied to one of the top or bottom deflection plates. In some instances, the top and bottom deflection plates may be L-shaped deflection plates.
Guiding of charged particles through capillaries in insulating materials
Stolterfoht, Nikolaus; Yamazaki, Yasunori
2016-04-01
Studies of charged particle guiding through capillaries in insulating materials, performed during the last decade, are reviewed in a comprehensive manner. First, the principles of capillary guiding of slow highly charged ions are introduced describing the self-organized formation of charge patches. Basic quantities are defined, such as the guiding power characterizing a capillary. Challenges of the guiding experiments are pointed out. Then, experiments are described with emphasis on the guiding of highly charged ions in the keV energy range. Samples with an array of nanocapillaries as well as single macrocapillaries are treated. Emission profiles of transmitted ions are analyzed to establish scaling laws for the guiding angle, which quantifies the guiding power. Oscillations of the mean ion emission angle reveal the temporal dynamics of the charge patch formation. Next, experiments with ions of high (MeV) energies are focused on single tapered capillaries allowing for the production of a microbeam for various applications. Experiments concerning electrons are presented showing that apart from being elastically scattered these negative particles may enter into the capillary surface where they suffer energy losses. Finally, theoretical concepts of the capillary guiding are discussed. Simulations based on different charge transport methods clearly support the understanding of the guiding mechanisms. Altogether, capillary guiding involves several novel phenomena for which understanding have progressed far beyond their infancy.
Charged particle layers in the Debye limit
We develop an equivalent of the Debye-Hueckel weakly coupled equilibrium theory for layered classical charged particle systems composed of one single charged species. We consider the two most important configurations, the charged particle bilayer and the infinite superlattice. The approach is based on the link provided by the classical fluctuation-dissipation theorem between the random-phase approximation response functions and the Debye equilibrium pair correlation function. Layer-layer pair correlation functions, screened and polarization potentials, static structure functions, and static response functions are calculated. The importance of the perfect screening and compressibility sum rules in determining the overall behavior of the system, especially in the r→∞ limit, is emphasized. The similarities and differences between the quasi-two-dimensional bilayer and the quasi-three-dimensional superlattice are highlighted. An unexpected behavior that emerges from the analysis is that the screened potential, the correlations, and the screening charges carried by the individual layers exhibit a marked nonmonotonic dependence on the layer separation
Light Charged Particles as Gateway to Hyperdeformation
The Euroball-IV γ -detector array, equipped with the ancillary charged particle detector array DIAMANT was used to study the residues of the fusion reaction 64Ni + 64Ni → 128Ba at Ebeam = 255 and 261 MeV, in an attempt to reach the highest angular momentum and verify the existence of predicted hyperdeformed rotational bands. No discrete hyperdeformed bands were identified, but nevertheless a breakthrough was obtained through a systematic search for rotational ridge structures with very large moments of inertia J(2) ≥ 100 ℎ2 MeV(-1), in agreement with theoretical predictions for hyperdeformed shapes. Evidence for hyperdeformation was obtained by charged particle + γ -ray gating, selecting triple correlated ridge structures in the continuum of each of the nuclei, 118Te, 124Xe and 124,125Cs. In 7 additional nuclei, rotational ridges were also identified with J(2) = 71-77 ℎ2 MeV(-1), which most probably correspond to superdeformed shape. The angular distributions of the emitted charged particles show an excess in forward direction over expectations from pure compound evaporation, which may indicate that in-complete fusion plays an important role in the population of very elongated shapes. (author)
Charge Transport in Weyl Semimetals
Hosur, Pavan; Parameswaran, S. A.; Vishwanath, Ashvin
2011-01-01
We study transport in three dimensional Weyl semimetals with N isotropic Weyl nodes in the presence of Coulomb interactions or disorder at temperature T. In the interacting clean limit, we determine the conductivity by solving a quantum Boltzmann equation within a `leading log' approximation and find it to be proportional to T, upto logarithmic factors arising from the flow of couplings. In the noninteracting disordered case, we compute the finite-frequency Kubo conductivity and show that it ...
Motion of charged particles in the magnetosphere
The adiabatic motion of charged particles in the magnetosphere has been investigated using Mead-Fairfield magnetospheric field model (Mead and Fairfield, 1975). Since the motion of charged particles in a dipolar field geometry is well understood, we bring out in this paper some important features in characteristic motion due to non-dipolar distortions in the field geometry. We look at the tilt averaged picture of the field configuration and estimate theoretically the parameters like bounce period, longitudinal invariant and the bounce averaged drift velocities of the charged particle in the Mead-Fairfield field geometry. These parameters are evaluated as a function of pitch angle and azimuthal position in the region of ring current (5 to 7 Earth radii from the centre of the Earth) for four ranges of magnetic activity. At different longitudes the non-dipolar contribution as a percentage of dipole value in bounce period and longitudinal invariant shows maximum variation for particles close to 900 pitch angles. For any low pitch angle, these effects maximize at the midnight meridian. The radial component of the bounce averaged drift velocity is found to be greatest at the dawn-dusk meridians and the contribution vanishes at the day and midnight meridians for all pitch angles. In the absence of tilt-dependent terms in the model, the latitudinal component of the drift velocity vanishes. On the other hand, the relative non-dipolar contribution to bounce averaged azimuthal drift velocity is very high as compared to similar contribution in other characteristic parameters of particle motion. It is also shown that non-dipolar contribution in bounce period, longitudinal invariant and bounce averaged drift velocities increases in magnitude with increase in distance and magnetic activity. (orig.)
Magnetic fields for transporting charged beams
The transport of charged particle beams requires magnetic fields that must be shaped correctly and very accurately. During the last 20 years or so, many studies have been made, both analytically and through the use of computer programs, of various magnetic shapes that have proved to be useful. Many of the results for magnetic field shapes can be applied equally well to electric field shapes. A report is given which gathers together the results that have more general significance and would be useful in designing a configuration to produce a desired magnetic field shape. The field shapes studied include the fields in dipoles, quadrupoles, sextupoles, octupoles, septum magnets, combined-function magnets, and electrostatic septums. Where possible, empirical formulas are proposed, based on computer and analytical studies and on magnetic field measurements. These empirical formulas are often easier to use than analytical formulas and often include effects that are difficult to compute analytically. In addition, results given in the form of tables and graphs serve as illustrative examples. The field shapes studied include uniform fields produced by window-frame magnets, C-magnets, H-magnets, and cosine magnets; linear fields produced by various types of quadrupoles; quadratic and cubic fields produced by sextupoles and octupoles; combinations of uniform and linear fields; and septum fields with sharp boundaries
Charge-transport simulations in organic semiconductors
May, Falk
2012-07-06
In this thesis we have extended the methods for microscopic charge-transport simulations for organic semiconductors, where weak intermolecular interactions lead to spatially localized charge carriers, and the charge transport occurs as an activated hopping process between diabatic states. In addition to weak electronic couplings between these states, different electrostatic environments in the organic material lead to a broadening of the density of states for the charge energies which limits carrier mobilities. The contributions to the method development include (i) the derivation of a bimolecular charge-transfer rate, (ii) the efficient evaluation of intermolecular (outer-sphere) reorganization energies, (iii) the investigation of effects of conformational disorder on intramolecular reorganization energies or internal site energies and (iv) the inclusion of self-consistent polarization interactions for calculation of charge energies. These methods were applied to study charge transport in amorphous phases of small molecules used in the emission layer of organic light emitting diodes (OLED). When bulky substituents are attached to an aromatic core in order to adjust energy levels or prevent crystallization, a small amount of delocalization of the frontier orbital to the substituents can increase electronic couplings between neighboring molecules. This leads to improved charge-transfer rates and, hence, larger charge-mobility. We therefore suggest using the mesomeric effect (as opposed to the inductive effect) when attaching substituents to aromatic cores, which is necessary for example in deep blue OLEDs, where the energy levels of a host molecule have to be adjusted to those of the emitter. Furthermore, the energy landscape for charges in an amorphous phase cannot be predicted by mesoscopic models because they approximate the realistic morphology by a lattice and represent molecular charge distributions in a multipole expansion. The microscopic approach shows that
Experimental research of thermoemission charging of metal particles
Original experimental methods of thermoemission charge determination of a spherical metallic particle surrounded by the condensed disperse phase are proposed. The analytical dependence of the particle charge on time is found, and its relaxation time is determined
Polaronic charge transport mechanism in DNA
Hennig, Dirk; Archilla, Juan F. R.
2006-01-01
For the detailed understanding of the conduction mechanism in DNA we use models based on the concept of polaron and breather solutions. We describe how charge transport relies on the coupling of the charge carrying unit to the vibrational modes of DNA allowing for the formation of polaron-like localised states. The mobility of these localised states is discussed particularly in the presence of parametrical and structural disorder inherent to biomolecules. It is demonstrated tha...
Charge Transport in DNA-Based Devices
Porath, Danny; Cuniberti, Gianaurelio; Di Felice, Rosa
2004-01-01
Charge migration along DNA molecules has attracted scientific interest for over half a century. Reports on possible high rates of charge transfer between donor and acceptor through the DNA, obtained in the last decade from solution chemistry experiments on large numbers of molecules, triggered a series of direct electrical transport measurements through DNA single molecules, bundles and networks. These measurements are reviewed and presented here. From these experiments we conclude that elect...
Charge Transport in DNA - Insights from Simulations
Wolter, Mario
2013-01-01
Charge transport and charge transfer (CT) capabilities of deoxyribonucleic acid (DNA) are investigated. A QM/MM multi-scale framework is applied to calculate the CT capabilities of DNA under conditions resembling the experimental setup. The simulations are able to explain and predict the outcome of experiments and therefore make suggestions in advance. Based on the findings, suitable DNA sequences can be opted for the design of DNA-based devices as nano-scale electronic elements.
Charge transport in DNA-based devices
Porath, Danny; Cuniberti, Gianaurelio; Felice, Rosa di
2004-01-01
Charge migration along DNA molecules attracted scientific interest for over half a century. Reports on possible high rates of charge transfer between donor and acceptor through the DNA, obtained in the last decade from solution chemistry experiments on large numbers of molecules, triggered a series of direct electrical transport measurements through DNA single molecules, bundles and networks. These measurements are reviewed and presented here. From these experiments we conclude that electrica...
Metastable states of plasma particles close to a charged surface
The free energy of the plasma particles and the charged surface that form an electroneutral system is calculated on the basis of the Poisson-Boltzmann equation. It is shown that, owing to correlation of light plasma particles near the charged surface and close to heavy particles of high charge, there can be metastable states in plasma. The corresponding phase charts of metastable states of the separate components of plasma, and plasma as a whole, are constructed. These charts depend on temperature, the charge magnitude, the size of the particles, and the share of the charge of the light carriers out of the total charge of the plasma particles
Radiation reaction for a massless charged particle
Kazinski, P O; Sharapov, A A [Physics Faculty, Tomsk State University, Tomsk, 634050 (Russian Federation)
2003-07-07
We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.
Radiation reaction for a massless charged particle
Kazinski, P O
2003-01-01
We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field having regard to the radiation back reaction. It is shown that unlike the massive case not all the divergences resulting from the self-action of the particle are Lagrangian, i.e. can be canceled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of homogeneous external field the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.
Radiation reaction for a massless charged particle
We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure
Radiation reaction for a massless charged particle
Kazinski, P. O.; Sharapov, A. A.
2003-07-01
We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.
A chemical analyzer for charged ultrafine particles
S. G. Gonser
2013-04-01
Full Text Available New particle formation is a frequent phenomenon in the atmosphere and of major significance for the earth's climate and human health. To date the mechanisms leading to the nucleation of particles as well as to aerosol growth are not completely understood. A lack of appropriate measurement equipment for online analysis of the chemical composition of freshly nucleated particles is one major limitation. We have developed a Chemical Analyzer for Charged Ultrafine Particles (CAChUP capable of analyzing particles with diameters below 30 nm. A bulk of size separated particles is collected electrostatically on a metal filament, resistively desorbed and consequently analyzed for its molecular composition in a time of flight mass spectrometer. We report of technical details as well as characterization experiments performed with the CAChUP. Our instrument was tested in the laboratory for its detection performance as well as for its collection and desorption capabilities. The manual application of known masses of camphene (C10H16 to the desorption filament resulted in a detection limit between 0.5 and 5 ng, and showed a linear response of the mass spectrometer. Flow tube experiments of 25 nm diameter secondary organic aerosol from ozonolysis of alpha-pinene also showed a linear relation between collection time and the mass spectrometer's signal intensity. The resulting mass spectra from the collection experiments are in good agreement with published work on particles generated by the ozonolysis of alpha-pinene. A sensitivity study shows that the current setup of CAChUP is ready for laboratory measurements and for the observation of new particle formation events in the field.
Trapped-Particle-Mediated Damping and Transport
Weak axial variations in B(z) or φ(z) in Penning-Malmberg traps cause some particles to be trapped locally. This causes a velocity-space separatrix between trapped and passing populations, and collisional separatrix diffusion then causes mode damping and asymmetry-induced transport. This separatrix dissipation scales with collisionality as v1/2, so it dominates in low collisionallity plasmas. The confinement lifetime in the 'CamV' apparatus was dominated by a weak magnetic ripple with δB/B ∼ 10-3, and it appears likely that the ubiquitous (L/B)-2 lifetime scalings and other applied asymmetry scalings represent similar TPM effects. TPM transport will limit the containment of large numbers of positrons or p-bars, since TPM loss rates generally scale as total charge Q2, independent of length
Sound from charged particles in liquids
Two directions of sound application appearing during the charged particles passing through liquid - in biology and for charged particles registration are considered. Application of this sound in radiology is determined by a contribution of its hypersound component (approximately 109 Hz) to radiology effect of ionizing radiation on micro-organisms and cells. Large amplitudes and pressure gradients in a hypersound wave have a pronounced destructive breaking effect on various microobjects (cells, bacteria, viruses). An essential peculiarity of these processes is the possibility of control by choosing conditions changing hypersound generation, propagation and effect. This fact may lead not only to the control by radiaiton effects but also may explain and complete the analogy of ionizing radiation and ultrasound effect on bioobjects. The second direction is acoustic registration of passing ionizing particles. It is based on the possibility of guaranteed signal reception from a shower with 1015-1016 eV energy in water at distances of hundreds of meters. Usage of acoustic technique for neutrino registration in the DUMAND project permits to use a detecting volume of water with a mass of 109 t and higher
Alpha particles diffusion due to charge changes
Clauser, C. F., E-mail: cesar.clauser@ib.edu.ar; Farengo, R. [Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica and Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Bariloche (Argentina)
2015-12-15
Alpha particles diffusion due to charge changes in a magnetized plasma is studied. Analytical calculations and numerical simulations are employed to show that this process can be very important in the pedestal-edge-SOL regions. This is the first study that presents clear evidence of the importance of atomic processes on the diffusion of alpha particles. A simple 1D model that includes inelastic collisions with plasma species, “cold” neutrals, and partially ionized species was employed. The code, which follows the exact particle orbits and includes the effect of inelastic collisions via a Monte Carlo type random process, runs on a graphic processor unit (GPU). The analytical and numerical results show excellent agreement when a uniform background (plasma and cold species) is assumed. The simulations also show that the gradients in the density of the plasma and cold species, which are large and opposite in the edge region, produce an inward flux of alpha particles. Calculations of the alpha particles flux reaching the walls or divertor plates should include these processes.
Macroscopic spin and charge transport theory
Li Da-Fang; Shi Jun-Ren
2009-01-01
According to the general principle of non-equilibrium thermodynamics, we propose a set of macroscopic transport equations for the spin transport and the charge transport. In particular, the spin torque is introduced as a generalized 'current density' to describe the phenomena associated with the spin non-conservation in a unified framework. The Einstein relations and the Onsager relations between different transport phenomena are established. Specifically, the spin transport properties of the isotropic non-magnetic and the isotropic magnetic two-dimensional electron gases are fully described by using this theory, in which only the macroscopic-spin-related transport phenomena allowed by the symmetry of the system are taken into account.
Preface: Charge transport in nanoscale junctions
Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas
2008-09-01
Understanding the fundamentals of nanoscale charge transfer is pivotal for designing future nano-electronic devices. Such devices could be based on individual or groups of molecular bridges, nanotubes, nanoparticles, biomolecules and other 'active' components, mimicking wire, diode and transistor functions. These have operated in various environments including vacuum, air and condensed matter, in two- or three-electrode configurations, at ultra-low and room temperatures. Interest in charge transport in ultra-small device components has a long history and can be dated back to Aviram and Ratner's letter in 1974 (Chem. Phys. Lett. 29 277-83). So why is there a necessity for a special issue on this subject? The area has reached some degree of maturity, and even subtle geometric effects in the nanojunction and noise features can now be resolved and rationalized based on existing theoretical concepts. One purpose of this special issue is thus to showcase various aspects of nanoscale and single-molecule charge transport from experimental and theoretical perspectives. The main principles have 'crystallized' in our minds, but there is still a long way to go before true single-molecule electronics can be implemented. Major obstacles include the stability of electronic nanojunctions, reliable operation at room temperature, speed of operation and, last but not least, integration into large networks. A gradual transition from traditional silicon-based electronics to devices involving a single (or a few) molecule(s) therefore appears to be more viable from technologic and economic perspectives than a 'quantum leap'. As research in this area progresses, new applications emerge, e.g. with a view to characterizing interfacial charge transfer at the single-molecule level in general. For example, electrochemical experiments with individual enzyme molecules demonstrate that catalytic processes can be studied with nanometre resolution, offering a route towards optimizing biosensors at
DNA oligonucleotides damage in charge transport context
Kratochvílová, Irena; Bunček, M.; Šebera, Jakub; Záliš, Stanislav; Sychrovský, Vladimír; Mojzeš, P.; Schneider, Bohdan
Prague: -, 2012. s. 22-22. [International Workshop on Radiation Damage to DNA /12./. 02.06.2012-06.06.2012, Prague] Institutional support: RVO:61388963 ; RVO:68378271 ; RVO:86652036 ; RVO:61388955 Keywords : charge transport * DNA damage Subject RIV: CC - Organic Chemistry
The charge transport in polymeric gel electrolytes
Reiche, A
2001-01-01
The aim of the present thesis consisted in the study of the charge transport in gel electrolytes, which were obtained by photopolymerization of oligo(ethylene glycol) sub n -dimethacrylates with n=3, 9, and 23, and the survey of structure and property relations for the optimization of the electrolyte composition. The pressure dependence of the electric conductivity was measured. (HSI)
Simulations of charge transport in organic compounds
Vehoff, Thorsten
2010-05-05
We study the charge transport properties of organic liquid crystals, i.e. hexabenzocoronene and carbazole macrocycle, and single crystals, i.e. rubrene, indolocarbazole and benzothiophene derivatives (BTBT, BBBT). The aim is to find structure-property relationships linking the chemical structure as well as the morphology with the bulk charge carrier mobility of the compounds. To this end, molecular dynamics (MD) simulations are performed yielding realistic equilibrated morphologies. Partial charges and molecular orbitals are calculated based on single molecules in vacuum using quantum chemical methods. The molecular orbitals are then mapped onto the molecular positions and orientations, which allows calculation of the transfer integrals between nearest neighbors using the molecular orbital overlap method. Thus we obtain realistic transfer integral distributions and their autocorrelations. In case of organic crystals the differences between two descriptions of charge transport, namely semi-classical dynamics (SCD) in the small polaron limit and kinetic Monte Carlo (KMC) based on Marcus rates, are studied. The liquid crystals are investigated solely in the hopping limit. To simulate the charge dynamics using KMC, the centers of mass of the molecules are mapped onto lattice sites and the transfer integrals are used to compute the hopping rates. In the small polaron limit, where the electronic wave function is spread over a limited number of neighboring molecules, the Schroedinger equation is solved numerically using a semi-classical approach. The carbazole macrocycles form columnar structures arranged on a hexagonal lattice with side chains facing inwards, so columns can closely approach each other allowing inter-columnar and thus three-dimensional transport. We are able to show that, on the time-scales of charge transport, static disorder due to slow side chain motions is the main factor determining the mobility. The high mobility of rubrene is explained by two main
Charged particle beam current monitoring tutorial
A tutorial presentation is made on topics related to the measurement of charged particle beam currents. The fundamental physics of electricity and magnetism pertinent to the problem is reviewed. The physics is presented with a stress on its interpretation from an electrical circuit theory point of view. The operation of devices including video pulse current transformers, direct current transformers, and gigahertz bandwidth wall current style transformers is described. Design examples are given for each of these types of devices. Sensitivity, frequency response, and physical environment are typical parameters which influence the design of these instruments in any particular application. Practical engineering considerations, potential pitfalls, and performance limitations are discussed
Transport of 3D space charge dominated beams
In this paper we present the theoretical analysis and the computer code design for the intense pulsed beam transport. Intense beam dynamics is a very important issue in low-energy high-current accelerators and beam transport systems. This problem affects beam transmission and beam qualities. Therefore, it attracts the attention of the accelerator physicists worldwide. The analysis and calculation for the intense beam dynamics are very complicated, because the state of particle motion is dominated not only by the applied electromagnetic fields, but also by the beam-induced electromagnetic fields (self-fields). Moreover, the self-fields are related to the beam dimensions and particle distributions. So, it is very difficult to get the self-consistent solutions of particle motion analytically. For this reason, we combine the Lie algebraic method and the particle in cell (PIC) scheme together to simulate intense 3D beam transport. With the Lie algebraic method we analyze the particle nonlinear trajectories in the applied electromagnetic fields up to third order approximation, and with the PIC algorithm we calculate the space charge effects to the particle motion. Based on the theoretical analysis, we have developed a computer code, which calculates beam transport systems consisting of electrostatic lenses, electrostatic accelerating columns, solenoid lenses, magnetic and electric quadruples, magnetic sextupoles, octopuses and different kinds of electromagnetic analyzers. The optimization calculations and the graphic display for the calculated results are provided by the code. (authors)
CVD diamond sensors for charged particle detection
Krammer, Manfred; Berdermann, E; Bergonzo, P; Bertuccio, G; Bogani, F; Borchi, E; Brambilla, A; Bruzzi, Mara; Colledani, C; Conway, J; D'Angelo, P; Dabrowski, W; Delpierre, P A; Dencuville, A; Dulinski, W; van Eijk, B; Fallou, A; Fizzotti, F; Foulon, F; Friedl, M; Gan, K K; Gheeraert, E; Hallewell, G D; Han, S; Hartjes, F G; Hrubec, Josef; Husson, D; Kagan, H; Kania, D R; Kaplon, J; Kass, R; Koeth, T W; Lo Giudice, A; Lü, R; MacLynne, L; Manfredotti, C; Meier, D; Mishina, M; Moroni, L; Oh, A; Pan, L S; Pernicka, Manfred; Peitz, A; Perera, L P; Pirollo, S; Procario, M; Riester, J L; Roe, S; Rousseau, L; Rudge, A; Russ, J; Sala, S; Sampietro, M; Schnetzer, S; Sciortino, S; Stelzer, H; Stone, R; Suter, B; Tapper, R J; Tesarek, R; Trischuk, W; Tromson, D; Vittone, E; Walsh, A M; Wedenig, R; Weilhammer, Peter; Wetstein, M; White, C; Zeuner, W; Zöller, M
2001-01-01
CVD diamond material was used to build position-sensitive detectors for single-charged particles to be employed in high-intensity physics experiments. To obtain position information, metal contacts shaped as strips or pixels are applied to the detector surface for one- or two- dimensional coordinate measurement. Strip detectors 2*4 cm/sup 2/ in size with a strip distance of 50 mu m were tested. Pixel detectors of various pixel sizes were bump bonded to electronics chips and investigated. A key issue for the use of these sensors in high intensity experiments is the radiation hardness. Several irradiation experiments were carried out with pions, protons and neutrons exceeding a fluence of 10/sup 15/ particles/cm/sup 2/. The paper presents an overview of the results obtained with strip and pixel detectors in high-energy test beams and summarises the irradiation studies. (8 refs).
Device for measuring charge density distribution in charged particle beams
A device to measure charge density distribution in charged particle beams has been described. The device contains a set of hollow interinsulated current-receiving electrodes, recording system, and cooling system. The invention is aimed at the increase of admissible capacity of the beams measured at the expense of cooling efficiency increase. The aim is achieved by the fact, that in the device a dynamic evaporating-condensational cooling of electrodes is realized by means of cooling agent supply in perpendicular to their planes through the tubes introduced inside special cups. Spreading in radial direction over electrode surface the cooling agent gradually and intensively washes the side surface of the cup, after that, it enters the cooling cavity in the form of vapour-liquid mixture. In the cavity the cooling agent, supplied using dispensina and receiving collectors in which vapoUr is condensed, circulates. In the device suggested the surface of electrode cooling is decreased significantly at the expense of side surface of the cups which receives the electrode heat
Charge transport properties of CdMnTe radiation detectors
Prokopovich D. A.
2012-10-01
Full Text Available Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading charge collection is reduced with increasing values of bias voltage. The electron drift velocity was calculated from the rise time distribution of the preamplifier output pulses at each measured bias. From the dependence of drift velocity on applied electric field the electron mobility was found to be μn = (718 ± 55 cm2/Vs at room temperature.
High Energy Ionic Charge State Composition In Recent Large Solar Energetic Particle Events
Labrador, A. W.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; von Rosenvinge, T. T.
2003-01-01
The ionic charge states of solar energetic particles (SEPs) provide information on the temperature of source materials and on conditions during acceleration and transport. SAMPEX/MAST measures mean ionic charge states at > 15 MeV/nuc using the geomagnetic rigidity filter technique. Charge state measurements by MAST for gradual SEP events suggest a continuum of charge states correlated with abundance ratios for a variety of elements, similar to what is observed at lower energies. In case...
Monte Carlo Studies of Charge Transport Below the Mobility Edge
Jakobsson, Mattias
2012-01-01
Charge transport below the mobility edge, where the charge carriers are hopping between localized electronic states, is the dominant charge transport mechanism in a wide range of disordered materials. This type of incoherent charge transport is fundamentally different from the coherent charge transport in ordered crystalline materials. With the advent of organic electronics, where small organic molecules or polymers replace traditional inorganic semiconductors, the interest for this type of h...
Temperature Dependent Kinetics DNA Charge Transport
Wohlgamuth, Chris; McWilliams, Marc; Slinker, Jason
2012-10-01
Charge transport (CT) through DNA has been extensively studied, and yet the mechanism of this process is still not yet fully understood. Besides the benefits of understanding charge transport through this fundamental molecule, further understanding of this process will elucidate the biological implications of DNA CT and advance sensing technology. Therefore, we have investigated the temperature dependence of DNA CT by measuring the electrochemistry of DNA monolayers modified with a redox-active probe. By using multiplexed electrodes on silicon chips, we compare square wave voltammetry of distinct DNA sequences under identical experimental conditions. We vary the probe length within the well matched DNA duplex in order to investigate distance dependent kinetics. This length dependent study is a necessary step to understanding the dominant mechanism behind DNA CT. Using a model put forth by O'Dea and Osteryoung and applying a nonlinear least squares analysis we are able to determine the charge transfer rates (k), transfer coefficients (α), and the total surface concentration (&*circ;) of the DNA monolayer. Arrhenius like behavior is observed for the multiple probe locations, and the results are viewed in light of and compared to the prominent charge transport mechanisms.
Charge Redistribution and Transport in Molecular Contacts
Corso, Martina; Ondráček, Martin; Lotze, Christian; Hapala, Prokop; Franke, Katharina J.; Jelínek, Pavel; Pascual, J. Ignacio
2015-09-01
The forces between two single molecules brought into contact, and their connection with charge transport through the molecular junction, are studied here using non contact AFM, STM, and density functional theory simulations. A carbon monoxide molecule approaching an acetylene molecule (C2 H2 ) initially feels weak attractive electrostatic forces, partly arising from charge reorganization in the presence of molecular . We find that the molecular contact is chemically passive, and protects the electron tunneling barrier from collapsing, even in the limit of repulsive forces. However, we find subtle conductance and force variations at different contacting sites along the C2 H2 molecule attributed to a weak overlap of their respective frontier orbitals.
Mass-independent search for fractionally charged particles
A proposed mass-independent search for fractionally charged particles with the all-electrostatic line of the IsoTRACE Laboratory at University of Toronto is described. Sensitive measurement of the fractional charge is accomplished by (1) a judicious choice of ion source and ion species, (2) charge changing and electrostatic analysis before injection into the tandem accelerator, (3) molecular destruction, charge changing, and acceleration by the tandem, (4) charge state selection and E/q analysis after acceleration, and (5) particle energy measurement with a Si surface barrier detector. In addition, the mass of the fractionally charged particles can be determined by a time of flight spectrometer. Specific cases involving +- (1/3)e and +- (2/3)e particles are discussed. Also included in the discussion are: integral charge background rejection, the procedure of the search, the signature of the fractionally charged particles, he resolutions of the analyzers and detectors, and the expected energy and time of flight spectra
Transportation charges in the gas industry
British Gas was privatized in 1986, a monopoly with no direct competition and only very light regulation of the tariff market. The regulator had an obligation to enable competition to develop in the unregulated, large-quantity, contract market. Competitors required access to the BG-owned transportation network. The government has recently rejected the recommendation of divestiture of the supply business, but has accelerated the advent of competition to the domestic market. This paper considers the role of BG's transport charges in these developments, using its past behaviour as a guide, and identifying the issues for future regulation and development of the gas market. (Author)
Variational multiscale models for charge transport
Wei, Guo-Wei; Zheng, Qiong; Chen, Zhan; Xia, Kelin
2012-01-01
This work presents a few variational multiscale models for charge transport in complex physical, chemical and biological systems and engineering devices, such as fuel cells, solar cells, battery cells, nanofluidics, transistors and ion channels. An essential ingredient of the present models, introduced in an earlier paper (Bulletin of Mathematical Biology, 72, 1562-1622, 2010), is the use of differential geometry theory of surfaces as a natural means to geometrically separate the macroscopic ...
Understanding charge transport in molecular electronics.
Kushmerick, J J; Pollack, S K; Yang, J C; Naciri, J; Holt, D B; Ratner, M A; Shashidhar, R
2003-12-01
For molecular electronics to become a viable technology the factors that control charge transport across a metal-molecule-metal junction need to be elucidated. We use an experimentally simple crossed-wire tunnel junction to interrogate how factors such as metal-molecule coupling, molecular structure, and the choice of metal electrode influence the current-voltage characteristics of a molecular junction. PMID:14976024
Charge Transport In Metal-Organic Frameworks
Wiers, Brian Michael
2015-01-01
This dissertation documents efforts to synthesize and measure ionically and electronically conductive porous, three-dimensional metal-organic frameworks. Chapter 1 introduces concepts of conductivity, mixed-valency, measurement techniques and gives a survey of charge-transport in metal-organic and covalent-organic frameworks. Concepts that directed the work detailed in this thesis is given, as is a perspective on possible future avenues to generate conductive metal-organic frameworks and poss...
Simulating charge transport in flexible systems
Timothy Clark
2015-12-01
Full Text Available Systems in which movements occur on two significantly different time domains, such as organic electronic components with flexible molecules, require different simulation techniques for the two time scales. In the case of molecular electronics, charge transport is complicated by the several different mechanisms (and theoretical models that apply in different cases. We cannot yet combine time scales of molecular and electronic movement in simulations of real systems. This review describes our progress towards this goal.
Simulating charge transport in flexible systems
Timothy Clark
2015-01-01
Systems in which movements occur on two significantly different time domains, such as organic electronic components with flexible molecules, require different simulation techniques for the two time scales. In the case of molecular electronics, charge transport is complicated by the several different mechanisms (and theoretical models) that apply in different cases. We cannot yet combine time scales of molecular and electronic movement in simulations of real systems. This review describes our ...
DNA Charge Transport over 34 nm
Slinker, Jason D.; Muren, Natalie B.; Renfrew, Sara E.; Barton, Jacqueline K.
2011-01-01
Molecular wires show promise in nanoscale electronics but the synthesis of uniform, long conductive molecules is a significant challenge. DNA of precise length, by contrast, is easily synthesized, but its conductivity has not been explored over the distances required for nanoscale devices. Here we demonstrate DNA charge transport (CT) over 34 nm in 100-mer monolayers on gold. Multiplexed gold electrodes modified with 100-mer DNA yield sizable electrochemical signals from a distal, covalent Ni...
Biological contexts for DNA charge transport chemistry
Merino, Edward J.; Boal, Amie K.; Barton, Jacqueline K.
2008-01-01
Many experiments have now shown that double helical DNA can serve as a conduit for efficient charge transport (CT) reactions over long distances in vitro. These results prompt the consideration of biological roles for DNA-mediated CT. DNA CT has been demonstrated to occur in biologically relevant environments such as within the mitochondria and nuclei of HeLa cells as well as in isolated nucleosomes. In mitochondria, DNA damage that results from CT is funneled to a critical regulatory element...
Electrophysical Systems Based On Charged Particle Accelerators
Vorogushin, M F
2004-01-01
The advancement of the charged particle accelerator engineering affects appreciably the modern tendencies of the scientific and technological progress in the world. In a number of advanced countries, this trend is one of the most dynamically progressing in the field of applied science and high-technology production. Such internationally known firms as VARIAN, SIEMENS, PHILIPS, ELECTA, IBA, HITACHI, etc., with an annual budget of milliards of dollars and growth rate of tens of percent may serve as an example. Although nowadays the projects of new large-scale accelerators for physical research are not implemented so quickly and frequently as desired, accelerating facilities are finding ever-widening application in various fields of human activities. The contribution made by Russian scientists into high-energy beams physics is generally known. High scientific and technical potential in this field, qualified personnel with a high creative potential, modern production and test facilities and state-of-the-art techn...
Aberration compensation in charged particle projection lithography
Projection systems offer the opportunity to increase the throughput for charged particle lithography, because such systems image a large area of a mask directly on to a wafer as a single shot. Shots have to be imaged over a certain range of off-axis distances at the wafer to increase the writing speed, because shot sizes are limited to about 0.25x0.25 mm2 due to aberrations. In a projection system with only lenses, however, the aberrations for off-axis shots are still very large, and some aberration compensation elements need to be introduced. In this paper, three aberration compensation elements (deflectors, stigmators and dynamic focus lenses) are first discussed, a suite of newly developed software, called PROJECTION, based on this principle and our unified aberration theory is then described, and an illustrative example computed with the software is finally given
Precipitation particle charge distribution and evolution of East Asian rainbands
Takahashi, Tsutomu
2012-11-01
Numerous videosondes, balloon-borne surveyors of precipitation particle morphology and charge, have been launched into cloud systems in many, disparate locations in East Asia. Reported here are videosonde-based observations of early summer, Baiu rainbands at Tanegashima in southern Japan and of summer rainbands at Chiang Rai in northern Thailand. Precipitation particles are mapped by type and charge over the course of cloud development, allowing particle and charge evolution to be derived. The basic charge distribution as observed in Hokuriku winter thunderclouds at different cloud life stages was seen at different locations characterized by vertical velocity profiles in the cloud. The charge structure of the rainbands in both locations was a basic tripole. The major charge carriers were graupel and ice crystals. As graupel and ice crystal concentrations increased, not only did space charge increase, but per-particle charge also increased. Increased lightning activity was associated with higher particle space charge and lower cloud-top temperature. The particle charge evolution of these systems includes several fundamental features: a. active negative charging of graupel in an intense updraft, b. descent of negative graupel along the edge of an updraft column, c. merging of negative graupel with positively charged raindrops falling in the central cloud, and d. extended distribution of positive ice crystals in the stratiform cloud. The observations suggest that riming electrification was the main charge separation mechanism.
Charge transport in amorphous organic semiconductors
Lukyanov, Alexander
2011-03-15
Organic semiconductors with the unique combination of electronic and mechanical properties may offer cost-effective ways of realizing many electronic applications, e. g. large-area flexible displays, printed integrated circuits and plastic solar cells. In order to facilitate the rational compound design of organic semiconductors, it is essential to understand relevant physical properties e. g. charge transport. This, however, is not straightforward, since physical models operating on different time and length scales need to be combined. First, the material morphology has to be known at an atomistic scale. For this atomistic molecular dynamics simulations can be employed, provided that an atomistic force field is available. Otherwise it has to be developed based on the existing force fields and first principle calculations. However, atomistic simulations are typically limited to the nanometer length- and nanosecond time-scales. To overcome these limitations, systematic coarse-graining techniques can be used. In the first part of this thesis, it is demonstrated how a force field can be parameterized for a typical organic molecule. Then different coarse-graining approaches are introduced together with the analysis of their advantages and problems. When atomistic morphology is available, charge transport can be studied by combining the high-temperature Marcus theory with kinetic Monte Carlo simulations. The approach is applied to the hole transport in amorphous films of tris(8- hydroxyquinoline)aluminium (Alq{sub 3}). First the influence of the force field parameters and the corresponding morphological changes on charge transport is studied. It is shown that the energetic disorder plays an important role for amorphous Alq{sub 3}, defining charge carrier dynamics. Its spatial correlations govern the Poole-Frenkel behavior of the charge carrier mobility. It is found that hole transport is dispersive for system sizes accessible to simulations, meaning that calculated
Charge transport properties of CdMnTe radiation detectors
Kim K.; Rafiel, R.; Boardman, M.; Reinhard, I.; Sarbutt, A.; Watt, G.; Watt, C.; Uxa, S.; Prokopovich, D.A.; Belas, E.; Bolotnikov, A.E.; James, R.B.
2012-04-11
Growth, fabrication and characterization of indium-doped cadmium manganese telluride (CdMnTe)radiation detectors have been described. Alpha-particle spectroscopy measurements and time resolved current transient measurements have yielded an average charge collection efficiency approaching 100 %. Spatially resolved charge collection efficiency maps have been produced for a range of detector bias voltages. Inhomogeneities in the charge transport of the CdMnTe crystals have been associated with chains of tellurium inclusions within the detector bulk. Further, it has been shown that the role of tellurium inclusions in degrading chargecollection is reduced with increasing values of bias voltage. The electron transit time was determined from time of flight measurements. From the dependence of drift velocity on applied electric field the electron mobility was found to be n = (718 55) cm2/Vs at room temperature.
Searches for Fractionally Charged Particles: What Should Be Done Next?
Perl, Martin L.; /SLAC
2009-01-15
Since the initial measurements of the electron charge a century ago, experimenters have faced the persistent question as to whether elementary particles exist that have charges that are fractional multiples of the electron charge. I concisely review the results of the last 50 years of searching for fractional charge particles with no confirmed positive results. I discuss the question of whether more searching is worthwhile?
Anomalous Kinetics of Hard Charged Particles Dynamical Renormalization Group Resummation
Boyanovsky, D
1999-01-01
We study the kinetics of the distribution function for charged particles of hard momentum in scalar QED. The goal is to understand the effects of infrared divergences associated with the exchange of quasistatic magnetic photons in the relaxation of the distribution function. We begin by obtaining a kinetic transport equation for the distribution function for hard charged scalars in a perturbative expansion that includes hard thermal loop resummation. Solving this transport equation, the infrared divergences arising from absorption and emission of soft quasi-static magnetic photons are manifest in logarithmic secular terms. We then implement the dynamical renormalization group resummation of these secular terms in the relaxation time approximation. The distribution function (in the linearized regime) is found to approach equilibrium as $\\delta n_k(t) =\\delta n_k(t_o) e^{-2\\alpha T (t-t_o) and $\\alpha =e^2/4\\pi$. This anomalous relaxation is recognized to be the square of the relaxation of the single particle p...
Determination of colloidal particle surface charge from dielectrophoresis
Chavez, Marko; Nuansri, Rittirong; Mazza, Jacob; Ou-Yang, H. Daniel
2015-03-01
Electrophoresis (EP) is used to determine colloidal particle surface charge. However, when the Debye length is comparable to or larger than the particle size, electrophoresis cannot be reliably used to determine the surface charge due to counter ion retardation flow. Alexander et al. developed a theory relating colloidal osmotic pressure and particle surface charge. We use dielectrophoresis (DEP) to obtain a potential landscape based on the number density distribution of the particles in a non-uniform AC electric field. We determine the osmotic pressure from the DEP force and density profiles using Einstein's osmotic equilibrium equation. Surface charge obtained by DEP (thermodynamics) will be compared to that obtained by EP (electrokinetics).
Bibliography of integral charged particle nuclear data. Archival edition
This is the fourth annual edition of the National Nuclear Data Center charged-particle bibliography. This edition is cumulative and supersedes the previous editions. The bibliography's primary aims are to satisfy the need for a concise and comprehensive index of integral charged-particle cross section data and to provide an index of charged-particle data compiled in the international exchange format. References in this Part are by target for the various incident charged particles (in order of increasing A). The present publication is an archival volume; future publications will be cumulative supplements to this edition
VEDs for charged particle accelerators: Indian scenario
In the initial times after their invention, the charged particle accelerators have, primarily, been used for fundamental studies on nuclei and atoms. From the first modern accelerator, the cathode ray tube, used by J.J. Thomson for the discovery of electron, very recently the gigantic 27 km circumference Large Hadron Collider (LHC) is operational in the search of Higg's boson and related physics issues. Particle accelerators have emerged as powerful microscopes for investigating the finest details of cells, genes, molecules, atoms, protons, neutrons, muons, electrons, quarks and, possibly, still undiscovered even more fundamental constituents of the universe, such as dark matter and dark energy. Several noble prize winning discoveries have been made using accelerators. Accelerators are now being used in a wide area of industrial and medical applications. They are used for the production of radioisotopes for medical imaging, cancer therapy, food sterilization, treatment of waste water, sterilization of medical equipment, material modification, mass spectroscopy, cargo scanning, fabrication of semiconductors etc. Ongoing effort towards the development of accelerators with megawatt beam power is showing hope for a cleaner source of nuclear energy and treatment of nuclear waste. Several tens of thousands of accelerators are presently operational in the world for basic research and applications. Development of new accelerators has several times been driven by new technologies and materials and sometimes they have driven the technological developments towards cutting edge. Some examples are ultra-high vacuum in large volumes, superfluid helium in cryogenics, cryocoolers, superconducting magnets and RF cavities, high power vacuum electronic devices, global control systems, superfast computing and communication networks, giant data storage/processing systems etc. India has been pursuing a fairly robust programme of accelerator development at various institutions. It
The effect of single-particle charge limits on charge distributions in dusty plasmas
An analytical expression for the stationary particle charge distribution in dusty plasmas is derived that accounts for the existence of single-particle charge limits. This expression is validated by comparison with the results of Monte Carlo charging simulations. The relative importance of the existence of charge limits for various values of the ratio of electron-to-ion density and ion mass is examined, and the effect of charge limits on the transient behavior of the charge distribution is considered. It is found that the time required to reach a steady-state charge distribution strongly decreases as the charge limit decreases, and that the existence of charge limits causes high-frequency charge fluctuations to become relatively more important than in the case without charge limits. (paper)
DNA Charge Transport within the Cell
Grodick, Michael A.; Muren, Natalie B.; Barton, Jacqueline K.
2015-01-01
The unique characteristics of DNA charge transport (CT) have prompted an examination of roles for this chemistry within a biological context. Not only can DNA CT facilitate long range oxidative damage of DNA, but redox-active proteins can couple to the DNA base stack and participate in long range redox reactions using DNA CT. DNA transcription factors with redox-active moieties such as SoxR and p53 can use DNA CT as a form of redox sensing. DNA CT chemistry also provides a means to monitor th...
Effects of charged particles on DNA
It can be noted that it is not simple double strand breaks (dsb) but the non-reparable breaks that are associated with high biological effectiveness in the cell killing effect for high LET radiation. Here, we have examined the effectiveness of fast neutrons and low (initial energy = 12 MeV/u) or high (135 MeV/u) energy charged particles on cell death in 19 mammalian cell lines including radiosensitive mutants. Some of the radiosensitive lines were deficient in DNA dsb repair such as LX830, M10, V3, and L5178Y-S cells and showed lower values of relative biological effectiveness (RBE) for fast neutrons if compared with their parent cell lines. The other lines of human ataxia-telangiectasia fibroblasts, irs 1, irs 2, irs 3 and irs 1SF cells, which were also radiosensitive but known as proficient in dsb repair, showed moderate RBEs. Dsb repair deficient mutants showed low RBE values for heavy ions. These experimental findings suggest that the DNA repair system does not play a major role against the attack of high linear energy transfer (LET) radiations. Therefore, we hypothesize that a main cause of cell death induced by high LET radiations is due to non-reparable dsb, which are produced at a higher rate compared to low LET radiations. (author)
Charged-particle beam: a safety mandate
The Advanced Test Accelerator (ATA) is a recent development in the field of charged particle beam research at Lawrence Livermore National Laboratory. With this experimental apparatus, researchers will characterize intense pulses of electron beams propagated through air. Inherent with the ATA concept was the potential for exposure to hazards, such as high radiation levels and hostile breathing atmospheres. The need for a comprehensive safety program was mandated; a formal system safety program was implemented during the project's conceptual phase. A project staff position was created for a safety analyst who would act as a liaison between the project staff and the safety department. Additionally, the safety analyst would be responsible for compiling various hazards analyses reports, which formed the basis of th project's Safety Analysis Report. Recommendations for safety features from the hazards analysis reports were incorporated as necessary at appropriate phases in project development rather than adding features afterwards. The safety program established for the ATA project faciliated in controlling losses and in achieving a low-level of acceptable risk
Terahertz transport dynamics of graphene charge carriers
Buron, Jonas Christian Due
The electronic transport dynamics of graphene charge carriers at femtosecond (10-15 s) to picosecond (10-12 s) time scales are investigated using terahertz (1012 Hz) time-domain spectroscopy (THz-TDS). The technique uses sub-picosecond pulses of electromagnetic radiation to gauge the electrodynamic...... response of thin conducting films at up to multi-terahertz frequencies. In this thesis THz-TDS is applied towards two main goals; (1) investigation of the fundamental carrier transport dynamics in graphene at femtosecond to picosecond timescales and (2) application of terahertz time-domain spectroscopy...... to rapid and non-contact electrical characterization of large-area graphene, relevant for industrial integration. We show that THz-TDS is an accurate and reliable probe of graphene sheet conductance, and that the technique provides insight into fundamental aspects of the nanoscopic nature of conduction...
Monte Carlo methods for particle transport
Haghighat, Alireza
2015-01-01
The Monte Carlo method has become the de facto standard in radiation transport. Although powerful, if not understood and used appropriately, the method can give misleading results. Monte Carlo Methods for Particle Transport teaches appropriate use of the Monte Carlo method, explaining the method's fundamental concepts as well as its limitations. Concise yet comprehensive, this well-organized text: * Introduces the particle importance equation and its use for variance reduction * Describes general and particle-transport-specific variance reduction techniques * Presents particle transport eigenvalue issues and methodologies to address these issues * Explores advanced formulations based on the author's research activities * Discusses parallel processing concepts and factors affecting parallel performance Featuring illustrative examples, mathematical derivations, computer algorithms, and homework problems, Monte Carlo Methods for Particle Transport provides nuclear engineers and scientists with a practical guide ...
Charge and Heat Transport in Polycrystalline Metallic Nanostructures
ZHANG Xing; TAKAHASHI Koji; FUJII Motoo
2008-01-01
Metals are typically good conductors in which the abilities to transport charge and to transport heat can be related through the Wiedemann-Franz law. Here we report on an abnormal charge and heat transport in polyerystalline metallic nanostructures in which the ability to transport charge is weakened more obviously than that to transport heat. We attribute it to the influence of the internal grain boundaries and have formulated a novel relation to predict the thermal conductivity. The Wiedemann-Franz law is then modified to account for the influence of the grain boundaries on the charge and heat transport with the predictions now agreeing well with the measured results.
Transport of Dust Particles in Tokamak Devices
Pigarov, A Y; Smirnov, R D; Krasheninnikov, S I; Rognlien, T D; Rozenberg, M
2006-06-06
Recent advances in the dust transport modeling in tokamak devices are discussed. Topics include: (1) physical model for dust transport; (2) modeling results on dynamics of dust particles in plasma; (3) conditions necessary for particle growth in plasma; (4) dust spreading over the tokamak; (5) density profiles for dust particles and impurity atoms associated with dust ablation in tokamak plasma; and (6) roles of dust in material/tritium migration.
Kumar, Satyam [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Dwivedi, G.D. [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Lourembam, J. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Kumar, Shiv; Saxena, U.; Ghosh, A.K. [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Chou, H. [Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Chatterjee, Sandip, E-mail: schatterji.app@iitbhu.ac.in [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)
2015-11-15
Structural, transport and optical properties of nano-crystalline Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} have been investigated to emphasize on the semiconducting properties of charge-ordered manganite. Rietveld refinement of X-ray diffraction pattern of Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles show that due to increase in sintering temperature, MnO{sub 6} octahedra elongated along z-direction and compressed in x-y plane. Both Mn–O–Mn angles are found to decrease with increasing sintering temperature. Fourier transform infrared (FTIR) spectroscopy measurements reveal that the stretching and bending vibration of Mn–O–Mn is responsible for the change in Mn–O–Mn bond length and bond angle respectively. With increasing sintering temperature, these vibrations tend to increase, which resulted in the further distortion of MnO{sub 6} octahedra. Magnetic measurements suggest that charge ordering is established and system becomes antiferromagnetic with increasing particle size. Resistivity behavior of Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles clearly exhibit semiconducting nature of these systems, which is due to the formation of charge-ordered state of Mn{sup 3+} and Mn{sup 4+}. Estimated optical band-gap of ∼3.7 eV for Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanocrystals, makes it a potential candidate for wide band-gap magnetic semiconductors. - Highlights: • Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles have been synthesized via sol–gel route. • Optical properties of charge-ordered Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} have been investigated. • Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles exhibit wide band-gap (3.7 eV) semiconducting nature. • Potential candidate for wide band-gap magnetic semiconductor device applications.
Particles and scalar waves in noncommutative charged black hole spacetime
Bhar, Piyali; Rahaman, Farook; Biswas, Ritabrata(Indian Institute of Engineering Sceince and Technology Shibpur (Formerly, Bengal Engineering and Science University Shibpur), 711 013, Howrah, West Bengal, India); Mondal, U. F.
2015-01-01
In this paper we have discussed geodesics and the motion of test particle in the gravitational field of noncommutative charged black hole spacetime. The motion of massive and massless particle have been discussed seperately. A comparative study of noncommutative charged black hole and usual Reissner-Nordstrom black hole has been done. The study of effective potential has also been included. Finally, we have examined the scattering of scalar waves in noncommutative charged black hole spacetime.
Particles and Scalar Waves in Noncommutative Charged Black Hole Spacetime
Piyali, Bhar; Farook, Rahaman; Ritabrata, Biswas; U. F., Mondal
2015-07-01
In this paper we have discussed geodesics and the motion of test particle in the gravitational field of non-commutative charged black hole spacetime. The motion of massive and massless particle have been discussed seperately. A comparative study of noncommutative charged black hole and usual Reissner-Nordström black hole has been done. The study of effective potential has also been included. Finally, we have examined the scattering of scalar waves in noncommutative charged black hole spacetime.
Dynamics of fast charged particle beam rotation in bended crystals
Dynamics of fast charged particle beam rotation in a bended monocrystal is considered. Face and volume mechanisms of capture in channels are taken into account simultaneously in the model presented. Functions of distribution in transverse energies (φ) of channeled and dechanneled particles are obtained. Charge-energy ''scale invariance'' in ion channeling with charge Z in a bended crystal determined by scale parameter W=pv/Z (p and v are pulse and velocity local to transverse planes) follows from the model presented
Charged particle periodicity in the Saturnian magnetosphere
The low energy charged particles (LECP) experiments on the Voyager 1 and 2 spacecraft performed measurements of electrons (approx.22 keV to approx.20 MeV) and ions (approx.28 keV to approx.150 MeV) during the Saturn encounters in 1980 and 1981. Count rate ratios of two of the low energy electron (22 to 35 keV and 183 to 500 keV) and ion (43 to 80 keV and 137 to 215 keV) channels exhibit an approximation 10 hour periodicity in the outer Saturnian magnetosphere beyond the orbit of Titan. Electron ratios vary from approx.50 to approx.300; ion ratios vary from approx.3 to approx.20. Similar but less pronounced periodicities are observed for higher and lower energy electron and ion spectral indices. Three complete cycles were observed during the Voyager 2 outbound portion of the encounter from which were determined an electron ratio period of 10/sup h/21/sup m/ +- 48/sup m/ and an ion ratio period of 9/sup h/49/sup m/ +- 59/sup m/. Using Saturn Kilometric Radiation (SKR) and Saturn Electrostatic Discharge (SED) periods, extrapolation backward from Voyager 2 to Voyager 1 suggests that the periodicities are Saturnian rather than Jovian in nature, and that they persist in phase for time intervals at least as long as 287 days. Ratio minima, or spectral hardenings, occur in the same hemisphere as do auroral brightenings, SKR activity, and spoke enhanement. We interpret the observations as prima facie evidence of an asymmetry in the Saturian magnetic field and the root cause of the observed SKR periodicity
Charge transport in single crystal organic semiconductors
Xie, Wei
Organic electronics have engendered substantial interest in printable, flexible and large-area applications thanks to their low fabrication cost per unit area, chemical versatility and solution processability. Nevertheless, fundamental understanding of device physics and charge transport in organic semiconductors lag somewhat behind, partially due to ubiquitous defects and impurities in technologically useful organic thin films, formed either by vacuum deposition or solution process. In this context, single-crystalline organic semiconductors, or organic single crystals, have therefore provided the ideal system for transport studies. Organic single crystals are characterized by their high chemical purity and outstanding structural perfection, leading to significantly improved electrical properties compared with their thin-film counterparts. Importantly, the surfaces of the crystals are molecularly flat, an ideal condition for building field-effect transistors (FETs). Progress in organic single crystal FETs (SC-FETs) is tremendous during the past decade. Large mobilities ~ 1 - 10 cm2V-1s-1 have been achieved in several crystals, allowing a wide range of electrical, optical, mechanical, structural, and theoretical studies. Several challenges still remain, however, which are the motivation of this thesis. The first challenge is to delineate the crystal structure/electrical property relationship for development of high-performance organic semiconductors. This thesis demonstrates a full spectrum of studies spanning from chemical synthesis, single crystal structure determination, quantum-chemical calculation, SC-OFET fabrication, electrical measurement, photoelectron spectroscopy characterization and extensive device optimization in a series of new rubrene derivatives, motivated by the fact that rubrene is a benchmark semiconductor with record hole mobility ~ 20 cm2V-1s-1. With successful preservation of beneficial pi-stacking structures, these rubrene derivatives form
Photon production by charged particles in narrow optical fibers
Artru, X.; Ray, C.
2006-01-01
Presented at International Conference on Charged and Neutral Particles Channeling Phenomena, Frascati, Italy, July 3-7, 2006. - Theorie, CAS A charged particle passing through or by an optical fiber induces emission of light guided by the fiber. The formula giving the spontaneous emission amplitude are given in the general case when the particle trajectory is not parallel to the fiber axis. At small angle, the photon yield grows like the inverse power of the angle and in the parallel limit...
Massive Vector Particles Tunneling From Noncommutative Charged Black Holes
Övgün, Ali
2015-01-01
In this paper, we investigate the tunneling process of charged massive bosons $W^{\\pm}$ (spin-1 particles) from noncommutative charged black holes such as charged RN black holes and charged BTZ black holes. By applying the WKB approximation and by using the Hamilton-Jacobi equation we derive the tunneling rate and the corresponding Hawking temperature for those black holes configuration. The tunneling rate shows that the radiation deviates from pure thermality and is consistent with an underlying unitary theory.
Particle with non-Abelian charge: classical and quantum
Lahiri, Amitabha
2010-01-01
We construct an action in the worldline formalism for a non-Abelian charged particle in a non-Abelian background field, described by real bosonic variables, leading to a set of the well known classical equations given by Wong. The isospin parts in the action can be viewed as the Lagrange multiplier term corresponding to a non-holonomic constraint restricting the isospins to be parallel transported. The path integration is performed over the isospin variables and their paths turn out to be constrained by its classical solution for the isospins. We derive a wave equation from the path integral, constructed as the constrained Hamiltonian operator acts on the wave function. It reveals what operator ordering corresponds to our classical Hamiltonian. It is verified by the inverse Weyl transformation.
Fractal like charge transport in polyaniline nanostructures
Nath, Chandrani; Kumar, A., E-mail: ask@tezu.ernet.in
2013-10-01
The structural and electrical properties of camphorsulfonic acid (CSA) doped nanotubes, and hydrochloric acid (HCl) doped nanofibers and nanoparticles of polyaniline have been studied as a function of doping level. The crystallinity increases with doping for all the nanostructures. Electrical transport measurements in the temperature range of 5–300 K show an increase in conductivity with doping for the nanostructures. All the nanostructures exhibit metal to insulator (MIT) transition below 40 K. The metallic behavior is ascribed to the electron–electron interaction effects. In the insulating regime of the nanotubes conduction follows the Mott quasi-1D variable range hopping model, whereas the conduction in the nanofibers and nanoparticles occur by variable range hopping of charge carriers among superlocalized states without and with Coulomb interaction, respectively. The smaller dopant size in case of HCl makes the polymer fractal resulting in superlocalization of electronic wave-functions. The confined morphology of the nanoparticles results in effective Coulomb interaction dominating the intersite hopping.
Charge transport in holography with momentum dissipation
Goutéraux, B
2014-01-01
In this work, we examine how charge is transported in a theory where momentum is relaxed by spatially dependent, massless scalars. We analyze the possible IR phases in terms of various scaling exponents and the (ir)relevance of operators in the IR effective holographic theory with a dilaton. We compute the (finite) resistivity and encounter broad families of (in)coherent metals and insulators, characterized by universal scaling behaviour. The optical conductivity at zero temperature and low frequencies exhibits power tails which can decay or blow up, including in the metallic regime, swamping out the contribution from the Drude peak. Their frequency scaling can differ from the resistivity scaling due to the running of the dilaton.
Highly charged hollow latex particles prepared via seeded emulsion polymerization.
Nuasaen, Sukanya; Tangboriboonrat, Pramuan
2013-04-15
The carboxylated hollow latex (HL) particles possessing high surface charge density were conveniently prepared by using poly(styrene-co-acrylic acid) (P(St/AA)) as seed particles and methyl methacrylate (MMA)/divinylbenzene (DVB)/AA as monomers. Without seed removal, the hollow structure was simply tuned by adjusting the monomer/seed ratio and the monomer content. The monodisperse, spherical, and non-collapsed HL particles with double shell having the void of 280 nm were obtained from P(St/AA) seeds of 300 nm. The conductimetric back titration, SEM, TEM, and dynamic light scattering measurement revealed that the surface charge density, surface roughness, and size of HL particles significantly increased when applying the stepwise charging monomers/initiator. The highly charged HL particles would be well dispersed in coating film providing good optical properties, for example, opacity and whiteness. PMID:23428072
Anomalous mobility of highly charged particles in pores.
Qiu, Yinghua; Yang, Crystal; Hinkle, Preston; Vlassiouk, Ivan V; Siwy, Zuzanna S
2015-08-18
Single micropores in resistive-pulse technique were used to understand a complex dependence of particle mobility on its surface charge density. We show that the mobility of highly charged carboxylated particles decreases with the increase of the solution pH due to an interplay of three effects: (i) ion condensation, (ii) formation of an asymmetric electrical double layer around the particle, and (iii) electroosmotic flow induced by the charges on the pore walls and the particle surfaces. The results are important for applying resistive-pulse technique to determine surface charge density and zeta potential of the particles. The experiments also indicate the presence of condensed ions, which contribute to the measured current if a sufficiently high electric field is applied across the pore. PMID:26177843
Analysis of electrolyte transport through charged nanopores
Peters, P. B.; van Roij, R.; Bazant, M. Z.; Biesheuvel, P. M.
2016-05-01
We revisit the classical problem of flow of electrolyte solutions through charged capillary nanopores or nanotubes as described by the capillary pore model (also called "space charge" theory). This theory assumes very long and thin pores and uses a one-dimensional flux-force formalism which relates fluxes (electrical current, salt flux, and fluid velocity) and driving forces (difference in electric potential, salt concentration, and pressure). We analyze the general case with overlapping electric double layers in the pore and a nonzero axial salt concentration gradient. The 3 ×3 matrix relating these quantities exhibits Onsager symmetry and we report a significant new simplification for the diagonal element relating axial salt flux to the gradient in chemical potential. We prove that Onsager symmetry is preserved under changes of variables, which we illustrate by transformation to a different flux-force matrix given by Gross and Osterle [J. Chem. Phys. 49, 228 (1968), 10.1063/1.1669814]. The capillary pore model is well suited to describe the nonlinear response of charged membranes or nanofluidic devices for electrokinetic energy conversion and water desalination, as long as the transverse ion profiles remain in local quasiequilibrium. As an example, we evaluate electrical power production from a salt concentration difference by reverse electrodialysis, using an efficiency versus power diagram. We show that since the capillary pore model allows for axial gradients in salt concentration, partial loops in current, salt flux, or fluid flow can develop in the pore. Predictions for macroscopic transport properties using a reduced model, where the potential and concentration are assumed to be invariant with radial coordinate ("uniform potential" or "fine capillary pore" model), are close to results of the full model.
Bibliography of integral charged particle nuclear data. Archival edition
This is the fourth annual edition of the National Nuclear Data Center charged-particle bibliography. This edition is cumulative and supersedes the previous editions. The bibliography's primary aims are to satisfy the need for a concise and comprehensive index of integral charged-particle cross section data and to provide an index of charged-particle data compiled in the international exchange format, EXFOR. This part of the publication deals with isotope production; references are ordered by mass of the nuclide produced. The present publication is an archival volume; future publications will be cumulative supplements to this edition
Quantum interface to charged particles in a vacuum
Okamoto, Hiroshi
2015-11-01
A superconducting qubit device suitable for interacting with a flying electron has recently been proposed [Okamoto and Nagatani, Appl. Phys. Lett. 104, 062604 (2014), 10.1063/1.4865244]. Either a clockwise or counterclockwise directed loop of half magnetic flux quantum encodes a qubit, which naturally interacts with any single charged particle with arbitrary kinetic energy. Here, the device's properties, sources of errors, and possible applications are studied in detail. In particular, applications include detection of a charged particle essentially without applying a classical force to it. Furthermore, quantum states can be transferred between an array of the proposed devices and the charged particle.
Heavy-ion radiography applied to charged particle radiotherapy
The objectives of the heavy-ion radiography research program applied to the clinical cancer research program of charged particle radiotherapy have a twofold purpose: (1) to explore the manner in which heavy-ion radiography and CT reconstruction can provide improved tumor localization, treatment planning, and beam delivery for radiotherapy with accelerated heavy charged particles; and (2) to explore the usefulness of heavy-ion radiography in detecting, localizing, and sizing soft tissue cancers in the human body. The techniques and procedures developed for heavy-ion radiography should prove successful in support of charged particle radiotherapy
Defect states and disorder in charge transport in semiconductor nanowires
Ko, Dongkyun; Zhao, X. W.; Reddy, Kongara M.; Restrepo, O. D.; Mishra, R; Beloborodov, I. S.; Trivedi, Nandini; Padture, Nitin P.; W. Windl; Yang, F. Y.; Johnston-Halperin, E.
2011-01-01
We present a comprehensive investigation into disorder-mediated charge transport in InP nanowires in the statistical doping regime. At zero gate voltage transport is well described by the space charge limited current model and Efros-Shklovskii variable range hopping, but positive gate voltage (electron accumulation) reveals a previously unexplored regime of nanowire charge transport that is not well described by existing theory. The ability to continuously tune between these regimes provides ...
Particle Transport in Parallel-Plate Reactors
Rader, D.J.; Geller, A.S.
1999-08-01
A major cause of semiconductor yield degradation is contaminant particles that deposit on wafers while they reside in processing tools during integrated circuit manufacturing. This report presents numerical models for assessing particle transport and deposition in a parallel-plate geometry characteristic of a wide range of single-wafer processing tools: uniform downward flow exiting a perforated-plate showerhead separated by a gap from a circular wafer resting on a parallel susceptor. Particles are assumed to originate either upstream of the showerhead or from a specified position between the plates. The physical mechanisms controlling particle deposition and transport (inertia, diffusion, fluid drag, and external forces) are reviewed, with an emphasis on conditions encountered in semiconductor process tools (i.e., sub-atmospheric pressures and submicron particles). Isothermal flow is assumed, although small temperature differences are allowed to drive particle thermophoresis. Numerical solutions of the flow field are presented which agree with an analytic, creeping-flow expression for Re < 4. Deposition is quantified by use of a particle collection efficiency, which is defined as the fraction of particles in the reactor that deposit on the wafer. Analytic expressions for collection efficiency are presented for the limiting case where external forces control deposition (i.e., neglecting particle diffusion and inertia). Deposition from simultaneous particle diffusion and external forces is analyzed by an Eulerian formulation; for creeping flow and particles released from a planar trap, the analysis yields an analytic, integral expression for particle deposition based on process and particle properties. Deposition from simultaneous particle inertia and external forces is analyzed by a Lagrangian formulation, which can describe inertia-enhanced deposition resulting from particle acceleration in the showerhead. An approximate analytic expression is derived for particle
Mechanisms of Particle Charging by Surfactants in Nonpolar Dispersions.
Lee, Joohyung; Zhou, Zhang-Lin; Alas, Guillermo; Behrens, Sven Holger
2015-11-10
Electric charging of colloidal particles in nonpolar solvents plays a crucial role for many industrial applications and products, including rubbers, engine oils, toners, or electronic displays. Although disfavored by the low solvent permittivity, particle charging can be induced by added surfactants, even nonionic ones, but the underlying mechanism is poorly understood, and neither the magnitude nor the sign of charge can generally be predicted from the particle and surfactant properties. The conclusiveness of scientific studies has been limited partly by a traditional focus on few surfactant types with many differences in their chemical structure and often poorly defined composition. Here we investigate the surface charging of poly(methyl methacrylate) particles dispersed in hexane-based solutions of three purified polyisobutylene succinimide polyamine surfactants with "subtle" structural variations. We precisely vary the surfactant chemistry by replacing only a single electronegative atom located at a fixed position within the polar headgroup. Electrophoresis reveals that these small differences between the surfactants lead to qualitatively different particle charging. In the respective particle-free surfactant solutions we also find potentially telling differences in the size of the surfactant aggregates (inverse micelles), the residual water content, and the electric solution conductivity as well as indications for a significant size difference between oppositely charged inverse micelles of the most hygroscopic surfactant. An analysis that accounts for the acid/base properties of all constituents suggests that the observed particle charging is better described by asymmetric adsorption of charged inverse micelles from the liquid bulk than by charge creation at the particle surface. Intramicellar acid-base interaction and intermicellar surfactant exchange help rationalize the formation of micellar ions pairs with size asymmetry. PMID:26484617
Facilitated transport of charged colloids in geologic media
Diffusion of a charged colloidal particle in a two-dimensional simple shear flow was studied by means of Monte Carlo calculations and the effects of a bounding wall and charge of a particle on convective diffusion were elucidated. Taking charge effects into account has a marked effect on the diffusion behavior of the particle, increasing the migration distance. Diffusion of latex colloidal particles in a quartz-powder packed cell was also studied by through-diffusion methods. For the large latex colloidal particles, the effective diffusion coefficients measured are larger than those estimated by Stokes-Einstein equation
Monte Carlo Particle Transport Capability for Inertial Confinement Fusion Applications
Brantley, P S; Stuart, L M
2006-11-06
A time-dependent massively-parallel Monte Carlo particle transport calculational module (ParticleMC) for inertial confinement fusion (ICF) applications is described. The ParticleMC package is designed with the long-term goal of transporting neutrons, charged particles, and gamma rays created during the simulation of ICF targets and surrounding materials, although currently the package treats neutrons and gamma rays. Neutrons created during thermonuclear burn provide a source of neutrons to the ParticleMC package. Other user-defined sources of particles are also available. The module is used within the context of a hydrodynamics client code, and the particle tracking is performed on the same computational mesh as used in the broader simulation. The module uses domain-decomposition and the MPI message passing interface to achieve parallel scaling for large numbers of computational cells. The Doppler effects of bulk hydrodynamic motion and the thermal effects due to the high temperatures encountered in ICF plasmas are directly included in the simulation. Numerical results for a three-dimensional benchmark test problem are presented in 3D XYZ geometry as a verification of the basic transport capability. In the full paper, additional numerical results including a prototype ICF simulation will be presented.
Charged particle interaction with a chirped electromagnetic pulse
Khachatryan, A. G.; Boller, K. -J.; Goor, van, Fred
2003-01-01
It is found that a charged particle can get a net energy gain from the interaction with an electromagnetic chirped pulse. Theoretically, the energy gain increases with the pulse amplitude and with the relative frequency variation in the pulse.
Charged particle beam scanning using deformed high gradient insulator
Chen, Yu -Jiuan
2015-10-06
Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.
Techniques used for charged particle nuclear data evaluation at CNDC
The methods and techniques used for Charged Particle Nuclear Data (CPND) evaluation at Chinese Nuclear Data Center (CNDC) are summarized, including compilation and evaluation of experimental data, nuclear reaction theory and model calculation, systematics research and comprehensive recommendation etc
Silicon pin diode array hybrids for charged particle detection
This paper reports on the design of silicon PIN diode array hybrids for use as charged particle detectors. A brief summary of the need for vertex detectors is presented. Circuitry, block diagrams and device specifications are included
Radiobiology with heavy charged particles: a historical review
Skarsgard, L.D. [Dept. of Medical Biophysics, B.C. Cancer Research Centre and TRIUMF, Vancouver (Canada)
1997-09-01
The presentation will attempt to briefly review some of radiobiological data on the effects of heavy charged particles and to discuss the influence of those studies on the clinical application which followed. (orig./MG)
Deposition of Aerosol Particles in Electrically Charged Membrane Filters
A theory for the influence of electric charge on particle deposition on the surface of charged filters has been developed. It has been tested experimentally on ordinary membrane filters and Nuclepore filters of 8 μm pore size, with a bipolar monodisperse test aerosol of 1 μm particle diameter, and at a filter charge up to 20 μC/m2. Agreement with theory was obtained for the Coulomb force between filter and particle for both kinds of filters. The image force between charged filter and neutral particles did not result in the predicted deposition in the ordinary membrane filter, probably due to lacking correspondence between the filter model employed for the theory, and the real filter. For the Nuclepore filter a satisfactory agreement with theory was obtained, also at image interaction
On the charged particle shock acceleration
The shock acceleration method employs injection of beam particles into the linear accelerator unexcited structure. Upon injecting a wave of accelerating electromagnetic field is excited in the structure it catches up with the particles and accelerates them. Dynamics of particle acceleration using the abovesaid method is under consideration. A d gree of particle beam compression in the process of beam acceleration is found out. New technique is suggested of shock acceleration with particle outlet to the potential barrier plateau that enables to attain compression not only of relativistic beams but also of non relativistic ones. It is shown that the method in question enables to get compression of electron and ion beams while increasing essentially their current and reducing the density modulation period. Shock acceleration in high current accelerators enables to obtain high-energy current beams (above 104A), which ght be used in studies on ionic thermonuclear fusion in powerful free electron lasers
Busscher, Henk J; Dijkstra, Rene J B; Engels, Eefje; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C
2006-11-01
Waterborne diseases constitute a threat to public health despite costly treatment measures aimed at removing pathogenic microorganisms from potable water supplies. This paper compared the removal of Raoultella terrigena ATCC 33257 and Escherichia coli ATCC 25922 by negatively and positively charged types of activated carbon particles. Both strains display bimodal negative zeta-potential distributions in stabilized water. Carbon particles were suspended to an equivalent external geometric surface area of 700 cm2 in 250 mL of a bacterial suspension, with shaking. Samples were taken after different durations for plate counting. Initial removal rates were less elevated for the positively charged carbon particle than expected, yielding the conclusion that bacterial adhesion under shaking is mass-transport limited. After 360 min, however, the log-reduction of the more negatively charged R. terrigena in suspension was largest for the positively charged carbon particles as compared with the negatively charged ones, although conditioning in ultrapure or tap water of positively charged carbon particles for 21 days eliminated the favorable effect of the positive charge due to counterion adsorption from the water. Removal of the less negatively charged E. coli was less affected by aging of the (positively charged) carbon particles, confirming the role of electrostatic interactions in bacterial removal by activated carbon particles. The microporous, negatively charged coconut carbon performed less than the mesoporous, positively charged carbon particle prior to conditioning but did not suffer from loss of effect after conditioning in ultrapure or tap water. PMID:17144313
Limits on the production of massive stable charged particles
We present improved limits on the production of massive stable charged particles in bar pp collisions using the Collider Detector at Fermilab based on an integrated luminosity of 3.54 pb-1. Both unit and fractionally charged particles are considered. Cross-section upper limits are determined for masses from 50 to 500 GeV/c2. Theoretical cross sections are used to set bounds on the mass of fermionic color triplets, sextets, octets, and decuplets as well as scalar triplets
Nuclear data needs in nuclear astrophysics: Charged-particle reactions
Progress in understanding a diverse range of astrophysical phenomena - such as the Big Bang, the Sun, the evolution of stars, and stellar explosions - can be significantly aided by improved compilation, evaluation, and dissemination of charged-particle nuclear reaction data. A summary of the charged-particle reaction data needs in these and other astrophysical scenarios is presented, along with recommended future nuclear data projects. (author)
Analogies between light optics and charged-particle optics
Khan, Sameen Ahmed
2002-01-01
The close analogy between geometrical optics and the classical theories of charged-particle beam optics have been known for a very long time. In recent years, quantum theories of charged-particle beam optics have been presented with the very expected feature of wavelength-dependent effects. With the current development of non-traditional prescriptions of Helmholtz and Maxwell optics respectively, accompanied with the wavelength-dependent effects, it is seen that the analogy between the two sy...
Proposal to Search for Magnetically Charged Particles with Magnetic Charge 1e
Sullivan, Michael K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fryberger, David [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-11-02
A model for composite elementary Standard Model (SM) particles based upon magnetically bound vorton pairs, we briefly introduce here, predicts the existence of a complete family of magnetically charged particles, as well as their neutral isotopic partners (all counterparts to the SM elementary particles), in which the lowest mass (charged) particle would be an electrically neutral stable lepton, but which carries a magnetic charge equivalent to 1e. This new particle, which we call a magneticon (a counterpart to the electron) would be pair produced at all e^{+}e^{-} colliders at an E_{cm} above twice its mass. In addition, PP and PPbar colliders should also be able to produce these new particles through the Drell-Yan process. To our knowledge, no monopole search experiment has been sensitive to such a low-charged magnetic monopole above a particle mass of about 5 GeV/c^{2}. Hence, we propose that a search for such a stable particle of magnetic charge 1e should be undertaken. We have taken the ATLAS detector at the LHC as an example in which this search might be done. To this end, we modeled the magnetic fields and muon trigger chambers of this detector. We show results from a simple Monte Carlo simulation program to indicate how these particles might look in the detector and describe how one might search for these new particles in the ATLAS data stream.
Asymptotic algebra for charged particles and radiation
A C*-algebra of asymptotic fields which properly describes the infrared structure in quantum electrodynamics is proposed. The algebra is generated by the null asymptotic of electromagnetic field and the time asymptotic of charged matter fields which incorporate the corresponding Coulomb fields. As a consequence Gauss' law is satisfied in the algebraic setting. Within this algebra the observables can be identified by the principle of gauge invariance. A class of representations of the asymptotic algebra is constructed which resembles the Kulish-Faddeev treatment of electrically charged asymptotic fields. (orig.)
Indirect Charged Particle Detection: Concepts and a Classroom Demonstration
Childs, Nicholas B.; Horányi, Mihály; Collette, Andrew
2013-01-01
We describe the principles of macroscopic charged particle detection in the laboratory and their connections to concepts taught in the physics classroom. Electrostatic dust accelerator systems, capable of launching charged dust grains at hypervelocities (1-100 km/s), are a critical tool for space exploration. Dust grains in space typically have…
An improved search for elementary particles with fractional electric charge
The SLAC Quark Search Group has demonstrated successful operation of a low cost, high mass throughput Millikan apparatus designed to search for fractionally charged particles. About six million silicone oil drops were measured with no evidence of fractional charges. A second experiment is under construction with 100 times greater throughput which will utilize optimized search fluids
Weakly nonlinear electrophoresis of a highly charged colloidal particle
Schnitzer, Ory; Zeyde, Roman; Yavneh, Irad; Yariv, Ehud
2013-05-01
At large zeta potentials, surface conduction becomes appreciable in thin-double-layer electrokinetic transport. In the linear weak-field regime, where this effect is quantified by the Dukhin number, it is manifested in non-Smoluchowski electrophoretic mobilities. In this paper we go beyond linear response, employing the recently derived macroscale model of Schnitzer and Yariv ["Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction," Phys. Rev. E 86, 021503 (2012), 10.1103/PhysRevE.86.021503] as the infrastructure for a weakly nonlinear analysis of spherical-particle electrophoresis. A straightforward perturbation in the field strength is frustrated by the failure to satisfy the far-field conditions, representing a non-uniformity of the weak-field approximation at large distances away from the particle, where salt advection becomes comparable to diffusion. This is remedied using inner-outer asymptotic expansions in the spirit of Acrivos and Taylor ["Heat and mass transfer from single spheres in Stokes flow," Phys. Fluids 5, 387 (1962), 10.1063/1.1706630], with the inner region representing the particle neighborhood and the outer region corresponding to distances scaling inversely with the field magnitude. This singular scheme furnishes an asymptotic correction to the electrophoretic velocity, proportional to the applied field cubed, which embodies a host of nonlinear mechanisms unfamiliar from linear electrokinetic theories. These include the effect of induced zeta-potential inhomogeneity, animated by concentration polarization, on electro-osmosis and diffuso-osmosis; bulk advection of salt; nonuniform bulk conductivity; Coulomb body forces acting on bulk volumetric charge; and the nonzero electrostatic force exerted upon the otherwise screened particle-layer system. A numerical solution of the macroscale model validates our weakly nonlinear analysis.
Charged particle separation by an electrically tunable nanoporous membrane
We study the applicability of an electrically tunable nanoporous semiconductor membrane for the separation of nanoparticles by charge. We show that this type of membrane can overcome one of the major shortcomings of nanoporous membrane applications for particle separation: the compromise between membrane selectivity and permeability. The computational model that we have developed describes the electrostatic potential distribution within the system and tracks the movement of the filtered particle using Brownian dynamics while taking into consideration effects from dielectrophoresis, fluid flow, and electric potentials. We found that for our specific pore geometry, the dielectrophoresis plays a negligible role in the particle dynamics. By comparing the results for charged and uncharged particles, we show that for the optimal combination of applied electrolyte and membrane biases the same membrane can effectively separate same-sized particles based on charge with a difference of up to 3 times in membrane permeability. (paper)
An imaging co-axial tube electrodynamic trap for manipulation of charged particles
A tubular particle trapping device was designed and fabricated using two co-axial electrically conductive tubes with diameters of 5 mm and 7 mm, respectively. The device was integrated with an imaging camera and optical fiber bundle for real time monitoring of trapped particle motion. Charged microparticles of 3 to 50 m diameter can be suspended in air at ambient pressure using the device utilizing a quadrupole potential with an alternating voltage of amplitude 300 V to 750 V and frequency of 30 Hz to 140 Hz. Controlled trapping of a single particle or multiple particles can be achieved by tuning the voltage amplitude. The particle remained trapped when the entire assembly was translated or rotated. The device can be used as a manipulator for charged particle transport and repositioning.
A high sensitivity selector for charged particles
The electrostatic size selector for aerosol particles, is composed of two coaxial parallel conductive disks between which an electric field is established; an annular slot in the first disk allows for the atmosphere air intake. Suction and injection systems, and a third intermediate disk are used to carry out a dynamic confinement that allows for the separation of the particles having the required electric mobility and therefore the required size
Gerts, David W; Bean, Robert S; Metcalf, Richard R
2013-02-19
A radiation detector is disclosed. The radiation detector comprises an active detector surface configured to generate charge carriers in response to charged particles associated with incident radiation. The active detector surface is further configured with a sufficient thickness for a partial energy deposition of the charged particles to occur and permit the charged particles to pass through the active detector surface. The radiation detector further comprises a plurality of voltage leads coupled to the active detector surface. The plurality of voltage leads is configured to couple to a voltage source to generate a voltage drop across the active detector surface and to separate the charge carriers into a plurality of electrons and holes for detection. The active detector surface may comprise one or more graphene layers. Timing data between active detector surfaces may be used to determine energy of the incident radiation. Other apparatuses and methods are disclosed herein.
Turbulence driven particle transport in Texas Helimak
We analyze the turbulence driven particle transport in Texas Helimak [K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)], a toroidal plasma device with a one-dimensional equilibrium with magnetic curvature and shear. Alterations on the radial electric field, through an external voltage bias, change the spectral plasma characteristics inducing a dominant frequency for negative bias values and a broad band frequency spectrum for positive bias values. When applying a negative bias, the transport is high where the waves propagate with phase velocities near the plasma flow velocity, an indication that the transport is strongly affected by a wave particle resonant interaction. On the other hand, for positive bias values, the plasma has a reversed shear flow, and we observe that the transport is almost zero in the shearless radial region, an evidence of a transport barrier in this region.
Kinetic transport simulation of energetic particles
Sheng, He; Waltz, R. E.
2016-05-01
A kinetic transport code (EPtran) is developed for the transport of the energetic particles (EPs). The EPtran code evolves the EP distribution function in radius, energy, and pitch angle phase space (r, E, λ) to steady state with classical slowing down, pitch angle scattering, as well as radial and energy transport of the injected EPs (neutral beam injection (NBI) or fusion alpha). The EPtran code is illustrated by treating the transport of NBI fast ions from high-n ITG/TEM micro-turbulence and EP driven unstable low-n Alfvén eigenmodes (AEs) in a well-studied DIII-D NBI heated discharge with significant AE central core loss. The kinetic transport code results for this discharge are compared with previous study using a simple EP density moment transport code ALPHA (R.E. Waltz and E.M. Bass 2014 Nucl. Fusion 54 104006). The dominant EP-AE transport is treated with a local stiff critical EP density (or equivalent pressure) gradient radial transport model modified to include energy-dependence and the nonlocal effects EP drift orbits. All previous EP transport models assume that the EP velocity space distribution function is not significantly distorted from the classical ‘no transport’ slowing down distribution. Important transport distortions away from the slowing down EP spectrum are illustrated by a focus on the coefficient of convection: EP energy flux divided by the product of EP average energy and EP particle flux.
Leske, R. A.; Mewaldt, R. A.; Cummings, A. C.; Stone, E. C.; von Rosenvinge, T. T.
2001-01-01
The ionic charge states of solar energetic particles (SEPs) depend upon the temperature of the source material and on the environment encountered during acceleration and transport during which electron stripping may occur. Measurements of SEP charge states at relatively high energies (≳15 MeV/nucleon) are possible with the Mass Spectrometer Telescope (MAST) on the Solar, Anomalous, and Magnetospheric Particle Explorer satellite by using the Earth's magnetic field as a particle rigidity filter...
Metal oxide charge transport material doped with organic molecules
Forrest, Stephen R.; Lassiter, Brian E.
2016-08-30
Doping metal oxide charge transport material with an organic molecule lowers electrical resistance while maintaining transparency and thus is optimal for use as charge transport materials in various organic optoelectronic devices such as organic photovoltaic devices and organic light emitting devices.
Course Notes: United States Particle Accelerator School Beam Physics with Intense Space-Charge
The purpose of this course is to provide a comprehensive introduction to the physics of beams with intense space charge. This course is suitable for graduate students and researchers interested in accelerator systems that require sufficient high intensity where mutual particle interactions in the beam can no longer be neglected. This course is intended to give the student a broad overview of the dynamics of beams with strong space charge. The emphasis is on theoretical and analytical methods of describing the acceleration and transport of beams. Some aspects of numerical and experimental methods will also be covered. Students will become familiar with standard methods employed to understand the transverse and longitudinal evolution of beams with strong space charge. The material covered will provide a foundation to design practical architectures. In this course, we will introduce you to the physics of intense charged particle beams, focusing on the role of space charge. The topics include: particle equations of motion, the paraxial ray equation, and the Vlasov equation; 4-D and 2-D equilibrium distribution functions (such as the Kapchinskij-Vladimirskij, thermal equilibrium, and Neuffer distributions), reduced moment and envelope equation formulations of beam evolution; transport limits and focusing methods; the concept of emittance and the calculation of its growth from mismatches in beam envelope and from space-charge non-uniformities using system conservation constraints; the role of space-charge in producing beam halos; longitudinal space-charge effects including small amplitude and rarefaction waves; stable and unstable oscillation modes of beams (including envelope and kinetic modes); the role of space charge in the injector; and algorithms to calculate space-charge effects in particle codes. Examples of intense beams will be given primarily from the ion and proton accelerator communities with applications from, for example, heavy-ion fusion, spallation