ID: 3601 The Baseline Positron Production and Capture Scheme for CLIC Speaker Olivier Dadoun (LAL, Orsay) Authors Olivier Dadoun, Pierre Lepercq, Freddy Poirier, Alessandro Variola (LAL, Orsay), Vladimir Strakhovenko (BINP SB RAS, Novosibirsk), Louis Rinolfi, Alessandro Vivoli (CERN, Geneva), Robert Chehab (IN2P3 IPNL, Villeurbanne), Tsunehiko Omori (KEK, Ibaraki) Abstract The CLIC study considers the hybrid source using channeling as the baseline for unpolarised positron production. The hybrid source uses a few GeV electron beam impinging on a crystal tungsten target. With the tungsten crystal oriented on its < 111 > axis it results an intense, relatively low energy photon beam due mainly to channeling radiation. Those photons are then impinging on an amorphous tungsten target producing positrons by e+e- pair creation. The downstream capture section is based on an adiabatic matching device and a 2 GHz pre-injector linac. The resulting studies are presented here. Funding Agency Type of Presentation Contributed Oral Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification A03 Linear Colliders

ID: 2901 An Undulator based Polarized Positron Source for CLIC Presenter Wei Gai (ANL, Argonne) Authors Wanming Liu, Wei Gai (ANL, Argonne), Louis Rinolfi (CERN, Geneva), John Sheppard (SLAC, Menlo Park, California) Abstract We propose a viable positron source scheme that uses circularly polarized gamma rays generated from the main 250 GeV electron beam. The beam passes through a helical superconducting undulator with a magnetic field of ~ 1 Tesla and a period of a few centimeters. The gamma-rays produced in the undulator in the energy range between ~ 3 MeV ~ 100 MeV will be directed to a titanium target and produces polarized positrons. The positrons are then captured, accelerated and transported to a damping ring. Detailed parameter studies of this scheme including positron yield, undulator parameter dependence and target composition and geometry will be presented. Effects on the 250 GeV drive beam, including emittance, energy spread and energy loss from the beam passing through the undulator will also be discussed. Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

ID: 2910 Update on the ILC Positron Source Study at ANL Presenter Wei Gai (ANL, Argonne) Authors Wanming Liu, Wei Gai (ANL, Argonne) Abstract We present an update on the ANL ILC positron source study. We examined the impact of different drive beam energies on the positron yield and polarization for the ILC RDR baseline undulator. The e+ yield is found to drop rapidly as the drive beam energy is reduced. We studied different undulator parameters for their effect on the positron yield and polarization when working at lower drive beam energies. Using a lower K (B field level) can increase the photon energy, but it is still very difficult to bring the yield up for low drive beam energies. For 250 GeV drive beam options, we studied the RDR undulator performance as a function of K. Instead of powering off some sections of the undulator, one can also consider lowering the B field to bring the positron yield back to the desired 1.5 e+/e-. We also studied the liquid lead target option for ILC positron source and the energy deposition in the reference design Ti target wheel. Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

ID: 2822 Design of a Pulsed Flux Concentrator for the ILC Positron Source Presenter Jeff Gronberg (LLNL, Livermore, California) Authors Jeff Gronberg, Ryan Abbott, Charles Brown, Jalal Javedani, William Thomas Piggott (LLNL, Livermore, California), James Clarke (STFC/DL/ASTeC, Daresbury, Warrington, Cheshire) Abstract The positron source at a future TeV scale electron linear collider will need to generate positrons at a rate two orders of magnitude larger than have been previously achieved. We report on a design of a 3.5 Tesla pulsed flux concentrator magnet which uses liquid nitrogen cooling of the flux concentrator plates to reduce the electrical resistance leading to reduced energy deposition and the ability to generate the required 1 ms pulse duration. This magnet can double the collection efficiency of positrons emitted from the target. Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

ID: 3516 Positron Source Simulations using Geant4 Presenter Andriy Ushakov (DESY Zeuthen, Zeuthen) Authors Andriy Ushakov, Sabine Riemann, Andreas Schaelicke (DESY Zeuthen, Zeuthen) Abstract The development of an intense polarised positron sources provides a challenge for a new generation of linear colliders. The software framework Geant4, a toolkit for simulation of the passage of particles trough matter, features tracking capabilities of charged particles in electromagnetic fields, and also includes the description of polarisation transfer in scattering processes. Based on Geant4 a novel simulation tool, PPS-Sim*, has been developed to optimise the design and to determine polarisation, beam properties, as well as energy deposition in accelerator components. All source components and their parameters can be chosen easily and flexible. Helical undulator, laser-Compton and coherent Bremsstrahlung in crystals are available as positron production schemes. Target materials and geometry can be adjusted. Flux concentrator, quarter wave transformer and lithium lens are implemented as possible capture devices. Geometry, accelerating components and magnetic field configuration can be specified by the user. In this contribution, PPS-Sim will be presented, and selected results for linear collider applications will be discussed. Footnotes * PPS-Sim web page - http://pps-sim.desy.de Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

ID: 3388 Eddy Current Studies From the Undulator-based Positron Source Target Wheel Prototype Presenter Ian Richard Bailey (Cockcroft Institute, Warrington, Cheshire; Lancaster University, Lancaster) Authors Ian Richard Bailey (Cockcroft Institute, Warrington, Cheshire; Lancaster University, Lancaster), James Clarke (Cockcroft Institute, Warrington, Cheshire; STFC/DL/ASTeC, Daresbury, Warrington, Cheshire), Lei Zang (Cockcroft Institute, Warrington, Cheshire; The University of Liverpool, Liverpool), Leo James Jenner (Imperial College of Science and Technology, London), Charles Brown, Jeff Gronberg, Lisle Hagler, William Thomas Piggott (LLNL, Livermore, California) Abstract The efficiency of future positron sources for the next generation of high-energy particle colliders (e.g. ILC, CLIC, LHeC) can be improved if the positron-production target is immersed in the magnetic field of adjacent capture optics. If the target is also rotating due to heat deposition considerations then eddy currents may be induced and lead to additional heating and stresses. In this paper we present data from a rotating target wheel prototype for the baseline ILC positron source. The wheel has been operated at revolution rates up to 1800rpm in fields of the order of 1 Tesla. Comparisons are made between torque data obtained from a transducer on the target drive shaft and the results of finite-element simulations. Rotordynamics issues are presented and future experiments on other aspects of the positron source target station are considered. Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

ID: 1858 Undulator Based Positron Source Optimization for CLIC Presenter Lei Zang (Cockcroft Institute, Warrington, Cheshire) Authors Lei Zang (Cockcroft Institute, Warrington, Cheshire), Ian Richard Bailey (Lancaster University, Lancaster), Andrzej Wolski (The University of Liverpool, Liverpool) Abstract CLIC will need of order 10 to the 14 positrons per second to achieve its specified luminosity. For such a challenge, an undulator based scheme has been proposed as one of the options for the positron source. As CLIC may operate over a wide range of energy (from 0.5 TeV to 3 TeV), there is a large margin for us to push the performance of the whole system to be more efficient. We report on the undulator parameters and optimization of components of the source such as conversion target, AMD, solenoid and capture RF for different operational scenarios. In addition to maximizing the positron yield the polarization of the positron beam are also considered. Funding Agency Type of Presentation Poster Main Classification 03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques Sub Classification T02 Lepton Sources

LCpositrons: ConferenceAbstracts (last edited 2010-10-04 16:42:06 by IanBailey)