Particle tracking in the ILC extraction lines with DIMAD and BDSIM

The study of beam transport is of central importance to the design and performance assessment of modern particle accelerators. In this paper, we benchmark two contemporary codes, DIMAD and BDSIM, the latter being a relatively new tracking code built within the framework of GEANT4. We consider both the 20 mrad and 2 mrad extraction lines of the 500 GeV International Linear Collider (ILC) and we perform particle tracking studies of heavily disrupted post-collision electron beams. We find that the two codes give an almost equivalent description of the beam transport

Benchmarking of Tracking Codes (BDSIM/DIMAD) using the ILC Extraction Lines

The study of beam transport is of central importance to the design and performance assessment of modern particle accelerators. In this work, we benchmark two contemporary codes - DIMAD and BDSIM, the latter being a relatively new tracking code built within the framework of GEANT4. We consider both the 20 mrad and 2 mrad extraction lines of the International Linear Collider (ILC) and we perform tracking studies of heavily disrupted post-collision electron beams. We find that the two codes mostly give an equivalent description of the beam transport.Comment: Contribution to the Tenth European Particle Accelerator Conference `"EPAC'06'', Edinburgh, United-Kingdom, 26-30 June 200

Optimization of the e-e- option for the ILC

The e-e- running mode is one of the interesting physics options at the International Linear Collider (ILC). The luminosity for e-e- collisions is reduced by the beam-beam effects. The resulting beamstrahlung energy loss and beam-beam deflection angles as function of the vertical transverse offset are different compared to the e+e- collisions. In this paper, the dependence of these observables with the offset for different beam sizes has been analyzed to optimize performances for the e-e- mode, taking into account the requirements of the beam-beam deflection based intra-train feedback system. A first study of the implications for the final focus and extraction line optics is also presented for the cases of the 20 mrad and 2 mrad ILC base line crossing angle geometries

Polarized Positron Source with a Compton Multiple Interaction Point Line

ISBN 978-3-95450-115-1International audiencePositron sources are critical components of the future lepton colliders projects. This is essentially due to the high luminosity required, orders of magnitude higher than existing ones. In addition,polarization of the positron beam rather expands the physics research potential of the machine by increasing the precision of the measurements and enhancing certain types of interactions. In this framework, the Compton sources for polarized positron production are taken into account where the high energy gamma rays are produced by the Compton scattering and subsequently converted in the polarized electron-positron pairs in a target. The Compton multiple IPs line is proposed as one of the solutions to increase the number of captured positrons. This allows a significant increase in the emitted gamma ray flux impinging on the target. The gamma ray production with the Compton multiple IPs line is simulated and used for polarized positron generation. Later, a capture section based on an adiabatic matching device followed by a pre-injector linac is simulated to capture and accelerate the positron beam. The results obtained are presented and discussed

BDSIM-Beamline Simulation Toolkit Based on GEANT4

http://cern.ch/AccelConf/e06/PAPERS/WEPCH124.PDFInternational audienceBDSIM is a code that combines accelerator-style par- ticle tracking with traditional Geant-style tracking based on Runge-Kutta techniques. This approach means that particle beams can be tracked efficiently when inside the beampipe, while also enabling full Geant4 processes when beam-particles interact with beamline apertures. Tracking of the resulting secondary particles is automatic. The code is described, including a new MAD-style interface and new geometry description, and key performance parameters are listed

Update on the Status of BDSIM

International audienceRecent updates to the status of the BDSIM particle tracking code are presented. In particular, we describe efforts to combine the secondary particle generation of BDSIM with the wakefield calculations of Placet in order to quantify backgrounds from col- limating elements in the beam delivery system of the International Linear Collider. Further recent updates to BDSIM are also introduced

Development of an intense positron source using a crystal--amorphous hybrid target for linear colliders

In a conventional positron source driven by a few GeV electron beam, a high amount of heat is loaded into a positron converter target to generate intense positrons required by linear colliders, and which would eventually damage the converter target. A hybrid target, composed of a single crystal target as a radiator of intense gamma--rays, and an amorphous converter target placed downstream of the crystal, was proposed as a scheme which could overcome the problem.This paper describes the development of an intense positron source with the hybrid target. A series of experiments on positron generation with the hybrid target has been carried out with a 8--GeV electron beam at the KEKB linac. We observed that positron yield from the hybrid target increased when the incident electron beam was aligned to the crystal axis and exceeded the one from the conventional target with the converter target of the same thickness, when its thickness is less than about 2 radiation length. The measurements in the temperature rise of the amorphous converter target was successfully carried out by use of thermocouples. These results lead to establishment to the evaluation of the hybrid target as an intense positron source.Comment: 17pages, 10figure

The Injection System of the INFN-SuperB Factory Project: Preliminary Design

THPEA007International audienceThe ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. Polarized electrons are required for experiments and must be delivered by the injection system, due to the beam lifetime shorter than the polarization build-up: they will be produced by means of a SLAC-SLC polarized gun. One or two 1 GeV damping rings are used to reduce e+ and e- emittances. Two schemes for positron production are under study, one with electron-positron conversion at low energy (<1 Gev), the second at 6 GeV with a recirculation line to bring the positrons back to the damping ring. Acceleration through the Linac is provided by a S-band RF system made of traveling wave, room temperature accelerating structures. An option to use the C-band technology is also presented

ERL Scheme for Compton Polarised Positron Sources

International audienceOne of the main challenges for the future linear colliders projects (ILC and CLIC) is to design an efficient positron source taking into account the constraints imposed by the target heating. At present, different schemes have been analysed to produce high energy gammas and to convert them in an amorphous target. One of them considers the possibility to boost the energy of the backscattered photons of a laser pulse by Compton effect. This method is very attractive since the source is independent from the main Linac and since the photon helicity is conserved in Compton scattering and subsequently transferred to the produced pairs. This allows the physics experiments disposing of both positron and electron polarised sources. Different schemes have been proposed to provide the electron beam for the Compton collisions. taking into account the constraint imposed by the low value of the Thomson cross section. One of the explored possibilities is to design an ERL with relatively low repetition frequency, high charge per pulse and then to stack the produced positrons in an accumulation ring. Different considerations on this scheme will be illustrated and the main constraints discussed. MO6RFP06

A positron source using an axially oriented crystal associated to a granular amorphous converter

Submitted to Chinese Physics CA non conventional positron source using the intense γ radiation from an axially oriented monocrystal which materialize into e+e- pairs in a granular amorphous converter is described. The enhancement of photon radiation by multi-GeV electrons crossing a tungsten crystal along its axis is reported. The resulting enhancement of pair production in an amorphous converter placed 2 meters downstream, is also reported. Sweeping off the charged particles from the crystal by a bending magnet upstream of the converter allows a significant reduction of the deposited energy density. Substituting a granular target made of small spheres to the usual compact one, makes easier the energy dissipation. The deposited energy and corresponding heating are analyzed and solutions for cooling are proposed. The configurations studied here for this kind of positron source allow its consideration for unpolarized positrons for the ILC