Rectlinear Cooling Scheme for Bright Muon Sources

In a hybrid 6D cooling channel, cooling is accomplished by reducing the beam momentum through ionization energy loss in wedge absorbers and replenishing the momentum loss in the longitudinal direction with gas-filled rf cavities. While the gas acts as a buffer to prevent rf breakdown, gas ionization also occurs as the beam passes through the pressurized cavity. The resulting plasma may gain substantial energy from the rf electric field which it can transfer via collisions to the gas, an effect known as plasma loading. In this paper, we investigate the influence of plasma loading on the cooling performance of a rectilinear hybrid channel. With the aid of numerical simulations we examine the sensitivity in cooling performance and plasma loading to key parameters such as the rf gradient and gas pressure.

The Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory aims to demonstrate 10% ionization cooling of a muon beam by its interaction with low-Z absorber materials followed by restoration of longitudinal momentum in RF linacs. MICE Step IV, including the rst LH 2 or LiH absorber cell sandwiched between two particle tracking spectrometers, is the collaboration's near-term goal. Two large superconducting spectrometer solenoids and one focus coil solenoid will provide a magnetic eld of 4 T in the tracker and absorber-cell volumes. The status of these components is described, as well as progress towards Steps V and VI, including the eight RF cavities to provide the required 8 MV/m gradient in a strong magnetic eld; this entails an RF drive system to deliver 2 MW, 1 ms pulses of 201 MHz frequency at 1 Hz repetition rate, the distribution network to deliver 1 MW to each cavity with correct RF phasing, diagnostics to determine the gradient and the muon transit phase, and development of the large-diameter magnets required for the linacs.

Hadrontherapy is an emerging technique in cancer therapy that uses beams of charged particles. To meet the improved capability of hadrontherapy in matching the dose release with the cancer position, new dose-monitoring techniques need to be developed and introduced into clinical use. The measurement of the fluxes of the secondary particles produced by the hadron beam is of fundamental importance in the design of any dose-monitoring device and is eagerly needed to tune Monte Carlo simulations. We report the measurements carried out with charged secondary particles produced from the interaction of a 80 MeV/u fully stripped carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a poly-methyl methacrylate target. Charged secondary particles, produced at 90° with respect to the beam axis, have been tracked with a drift chamber, while their energy and time of flight have been measured by means of a LYSO scintillator. Secondary protons have been identified exploiting the energy and time-of-flight information, and their emission region has been reconstructed backtracking from the drift chamber to the target. Moreover, a position scan of the target indicates that the reconstructed emission region follows the movement of the expected Bragg peak position. Exploiting the reconstruction of the emission region, an accuracy on the Bragg peak determination in the submillimeter range has been obtained. The measured differential production rate for protons produced with EProdkin > 83 MeV and emitted at 90° with respect to the beam line is dNP/(dNCdΩ) (EProdkin > 83 MeV, θ = 90°) = (2.69 ± 0.08stat ± 0.12sys) × 10−4 sr−1.

A statistical theory of the momentum and energy exchange between beams of particles interacting by Yukawa-type potentials is presented. A theoretical description is given for the slowing down of the beams, the thermalization and heating of the beams, and the establishment of the isothermal state in the beams. The associated collision integrals are evaluated, with consideration of the velocity dependence of various Coulomb logarithms. The kinetic processes are shown to depend crucially on whether the relative velocity of the beams is supersonic or subsonic. The theory is applicable to (i) beams of charged and neutral particles interacting by a Coulomb potential screened by bound electrons, and (ii) beams of charged particles interacting by a Coulomb potential screened by free charges. In the region of low energies, the results are applicable to the components of collision-dominated ionized gases and plasmas, and represent an essential contribution to the transport theory of collision-dominated media with nondivergent Coulomb interactions.

We calculate exact two-dimensional analytic expressions for the electric and magnetic fields and their potentials generated by a linear beam of relativistic charged particles between infinite ideally conducting planes and ferromagnetic poles. We use the method of summing an infinite sequence of fields of linear image charges and image currents to obtain solutions and also calculate the density distribution of the electric charge on the conductor surface induced by the charged particle beam. We obtain new formulas for the linear approximation of the fields near the beam and discuss the mathematical features of the exact solutions and the applicability constraints for the linear approximations.

Copyright © 2016 CC-BY-3.0 and by the respective authors. The measurement of beam bunch length with high resolution is very important for the latest generation light sources and also a key parameter for the optimization of the final beam quality in high gradient plasma accelerators. In this contribution we present progress in the development of novel single shot, RMS bunch length diagnostic techniques based on imaging the near and far fields of coherent THz diffraction radiation (CDR) that is produced as a charged particle beam interacts with a solid foil or an aperture. Recent simulation results show that the profile of a THz image of the point spread function (PSF) of a beam whose radius is less than the image produced by a single electron, is sensitive to bunch length and can thus be used as a diagnostic. The advantages of near (source) field imaging over far field imaging are examined and the results of recent high energy (20 GeV) CDR THz experiments at SLAC/FACET are presented. Plans for experiments to further validate and compare these imaging methods for both moderate and high energy charged particle beams are discussed.

Study of the response of the novel LAr LEM-TPC detector exposed to cosmic rays and a charged particle beam

The most obvious components of particle accelerators and beam transport systems are those that provide the beam guidance system. Whatever the application may be, a beam of charged particles is designed to follow closely a predescribed path along a desired beam transport line or along a closed orbit in case of circular accelerators. The forces required to bend and direct the charged particle beam or to hold particles close to the ideal path are known as the Lorentz forces and are derived from electric and magnetic fields through the Lorentz equation.

Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions at energies of up to several TeV at the Muon Collider. The International Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling, the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam passes through a material (the absorber) in which it loses energy. The energy lost is then replaced using RF cavities. The combined effect of energy loss and re-acceleration is to reduce the transverse emittance of the beam (transverse cooling). A major revision of the scope of the project was carried out over the summer of 2014. The revised project plan, which has received the formal endorsement of the international MICE Project Board and the international MICE Funding Agency Committee, will deliver a demonstration of ionization cooling by September 2017. In the revised configuration a central lithium-hydride absorber provides the cooling effect. The magnetic lattice is provided by the two superconducting focus coils and acceleration is provided by two 201 MHz single-cavity modules. The phase space of the muons entering and leaving the cooling cell will be measured by two solenoidal spectrometers. All the superconducting magnets for the ionization cooling demonstration are available at the Rutherford Appleton Laboratory and the first single-cavity prototype is under test in the MuCool Test Area at Fermilab. The design of the cooling demonstration experiment will be described together with a summary of the performance of each of its components. The cooling performance of the revised configuration will also be presented.

The most obvious components of particle accelerators and beam transport systems are those that provide the beam guidance and focusing system. Whatever the application may be, a beam of charged particles is expected by design to follow closely a prescribed path along a desired beam transport line or along a closed orbit in case of circular accelerators. The forces required to bend and direct the charged particle beam or provide focusing to hold particles close to the ideal path are known as the Lorentz forces and are derived from electric and magnetic fields through the Lorentz equation.

Passage of fast charged particles through bent crystals and nanotubes

A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium conditions of a relaxed plasma. The equilibrium conditions of a relaxed two species plasma are also computed. In such a scenario, space charge based electrostatic confinement is predicted to occur where a second plasma species is confined by the space charge of the first plasma species. An experimental apparatus with cylindrical symmetry that has its interior surface lined with an ASB is presented. This system was developed by using a simulation of the electro- magneto-static fields present within the trap to guide mechanical design. The construction of the full experimental apparatus is discussed. Experimental results that show the characteristics of electron beam transmission through the experimental apparatus are presented. A description of the experimental hardware and software used for trapping a charged particle beam or plasma is also presented.

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

This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators that are injectors to larger machines in high-energy physics facilities are not considered. An ABNS for BNCT is composed of: (1) the accelerator hardware for producing a high current charged particle beam, (2) an appropriate neutron-producing target and target heat removal system (HRS), and (3) a moderator/reflector assembly to render the flux energy spectrum of neutrons produced in the target suitable for patient irradiation. As a consequence of the efforts of researchers throughout the world, progress has been made on the design, manufacture, and testing of these three major components. Although an ABNS facility has not yet been built that has optimally assembled these three components, the feasibility of clinically useful ABNSs has been clearly established. Both electrostatic and radio frequency linear accelerators of reasonable cost (approximately 1.5 M dollars) appear to be capable of producing charged particle beams, with combinations of accelerated particle energy (a few MeV) and beam currents (approximately 10 mA) that are suitable for a hospital-based ABNS for BNCT. The specific accelerator performance requirements depend upon the charged particle reaction by which neutrons are produced in the target and the clinical requirements for neutron field quality and intensity. The accelerator performance requirements are more demanding for beryllium than for lithium as a target. However, beryllium targets are more easily cooled. The accelerator performance requirements are also more demanding for greater neutron field quality and intensity. Target HRSs that are based on submerged-jet impingement and the use of microchannels have emerged as viable target cooling options. Neutron fields for reactor-based neutron sources provide an obvious basis of comparison for ABNS field quality. This paper compares Monte Carlo calculations of neutron field quality for an ABNS and an idealized standard reactor neutron field (ISRNF). The comparison shows that with lithium as a target, an ABNS can create a neutron field with a field quality that is significantly better (by a factor of approximately 1.2, as judged by the relative biological effectiveness (RBE)-dose that can be delivered to a tumor at a depth of 6cm) than that for the ISRNF. Also, for a beam current of 10 mA, the treatment time is calculated to be reasonable (approximately 30 min) for the boron concentrations that have been assumed.

This paper contains results of development new version (2016) of program for channels design high-energy beams of charged particles. The program includes application package modeling the dynamics of charged particles in the channel, operational tools to change the channel parameters, channel optimization tools and processing output beam parameters with graphic and digital presentation of its key features. The MATLAB (Scilab) was used as programming tools, allows to make the source code modular, compact and scalable. New object-oriented graphical user interface provides an interactive assembly of new or modernization of previously developed channel - selection and arrangement of its elements, as well as the installation and the variation of their parameters. The relational database, which is part of the new version of program, providing additional functionality to the designer. It is intended for storage of the current development, and to preserve the previously completed projects, as well as other useful designer related information. A multi-output of all the main parameters of the beam at the output, as well as anywhere in the channel. In this case, the developer has the ability to interactively search and setting the optimum mode of operation channel.