Keyword: positron
Paper Title Other Keywords Page
MOPPC090 Coupling Modulator Simulations into an FEL Amplifier for Coherent Electron Cooling FEL, electron, simulation, radiation 346
 
  • I.V. Pogorelov, G.I. Bell, D.L. Bruhwiler, B.T. Schwartz, S.D. Webb
    Tech-X, Boulder, Colorado, USA
  • Y. Hao, V. Litvinenko, G. Wang
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics under grant numbers DE-FG02-08ER85182 and DE-SC0000835.
Next-generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques*. Particle-in-cell (PIC) simulations of a CeC modulator with the parallel VORPAL framework generate macro-particle distributions with subtle but important phase space correlations. To couple these macro-particles into a 3D simulation code for the free-electron laser (FEL) amplifier, while retaining all details of the 6D phase space coordinates, we implemented an alternative approach based on particle-clone pairs**. Our approach allows for self-consistent treatment of shot noise and spontaneous radiation, with no need for quiet-start initialization of the FEL macro-particles' ponderomotive phase. We present results of comparing fully 3D amplifier modeling based on the particle-clone approach vs GENESIS simulations where distribution of bunching parameter was used as input. We also discuss enabling direct coupling of the VORPAL delta-f simulation output into 3D distributions of particle-clone pairs.
* V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** V.N. Litvinenko, "Macro-particle FEL model with self-consistent spontaneous radiation," unpublished (2002). 		 
 
MOPPP031 A New Injection System for an Electron/Positron Linac linac, electron, injection, gun 628
 
  • C. Liebig, M. Hüning, M. Schmitz
    DESY, Hamburg, Germany
  
  For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% before the positron converter and the associated activation. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. Its main part is a traveling wave structure in 2π/3 mode, to which one capture cell is coupled in π mode. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. In addition, the design is analysed in a test rig before final installation. Test rig and subsequent injector are equipped with extensive diagnostics. Besides the design of the injection system results of simulations and measurements on the test rig will be presented.  
 
MOPPR025 The BPM DAQ System Upgrade for SuperKEKB Injector Linac linac, electron, emittance, injection 834
 
  • M. Satoh, K. Furukawa, F. Miyahara, T. Suwada
    KEK, Ibaraki, Japan
  • T. Kudou, S. Kusano
    MELCO SC, Tsukuba, Japan
  
  The non-destructive beam position monitor (BPM) is indispensable diagnostic tool for the stable beam operation. In the KEK Linac, approximately nineteen BPMs with the strip-line type electrodes are used for the beam orbit measurement and feedback. In addition, some of them are also used for the beam energy feedback loops. The current DAQ system consists of the fast digital oscilloscopes. A signal from each electrode is analyzed with a predetermined response function up to 50 Hz. The beam position resolution of current system is limited to about 0.5 mm because of ADC resolution. Towards SuperKEKB project, we have a plan to upgrade the BPM DAQ system since the Linac should provide the smaller emittance beam. We will report the system description of the new DAQ system and the results of performance test in detail.  
 
MOPPR034 A Laser Wire System at Electron Beam Transport Line in BEPCII laser, electron, photon, simulation 852
 
  • C. Zhang, J. Cao, Q.Y. Deng, Y.F. Sui
    IHEP, People's Republic of China
  
  Funding: National Natural Science Foundation of China
A Laser Wire system is under development at transport line in BEPCII (Beijing Electron Positron Collider). The structure of whole system is briefly described in this paper. Some work on laser and detector are presented. We also discussed the challenge of Laser Wire and some other things that can affect measurement. According to the plan, the Laser Wire will be installed in electron beam transport line in the summer of 2012. 		 
 
TUOBC03 Experimental Measurements of e-Cloud Mitigation using Clearing Electrodes in the DAΦNE Collider vacuum, wiggler, dipole, electron 1107
 
  • D. Alesini, T. Demma, A. Drago, A. Gallo, S. Guiducci, C. Milardi, P. Raimondi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • S. De Santis
    LBNL, Berkeley, California, USA
  
  Recently the electron-positron collider DAΦNE has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes for e-cloud clearing were installed in all the dipole and wiggler magnets of the collider positron ring. Experimental measurements of the effectiveness of the electrodes in the mitigation of the e-cloud effects in the positron beam have been done showing an impressive effectiveness of these devices in the cure of the e-cloud effects in the positron beam. In particular the electrodes allow reducing the vertical beam size increase, the growth rate of transverse instabilities and the tune shifts induced by the electron cloud. Frequency shifts measurements of the vacuum chamber resonances switching on and off the electrodes have also been done showing their effect in the reduction of the electron cloud density. In this paper we summarize the results of all our observations and the experimental measurements of the e-cloud suppression with these electrodes.  
slides icon Slides TUOBC03 [2.825 MB]  
 
TUPPC086 Conceptual Design of the CLIC damping rings emittance, wiggler, damping, vacuum 1368
 
  • Y. Papaphilippou, F. Antoniou, M.J. Barnes, S. Calatroni, P. Chiggiato, R. Corsini, A. Grudiev, J. Holma, T. Lefèvre, M. Martini, M. Modena, N. Mounet, A. Perin, Y. Renier, G. Rumolo, S. Russenschuck, H. Schmickler, D. Schoerling, D. Schulte, M. Taborelli, G. Vandoni, F. Zimmermann
    CERN, Geneva, Switzerland
  • C. Belver-Aguilar, A. Faus-Golfe
    IFIC, Valencia, Spain
  • A. Bernhard
    KIT, Karlsruhe, Germany
  • M.J. Boland
    ASCo, Clayton, Victoria, Australia
  • A.V. Bragin, E.B. Levichev, S.V. Sinyatkin, P. Vobly, K. Zolotarev
    BINP SB RAS, Novosibirsk, Russia
  • M. Korostelev
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • E. Koukovini
    EPFL, Lausanne, Switzerland
  • M.A. Palmer
    CLASSE, Ithaca, New York, USA
  • M.T.F. Pivi, S.R. Smith
    SLAC, Menlo Park, California, USA
  • R.P. Rassool, K.P. Wootton
    The University of Melbourne, Melbourne, Australia
  • L. Rinolfi
    JUAS, Archamps, France
  • A. Vivoli
    Fermilab, Batavia, USA
  
  The CLIC damping rings are designed to produce unprecedentedly low-emittances of 500 nm and 5 nm normalized at 2.86 GeV, in all beam dimensions with high bunch charge, necessary for the performance of the collider. The large beam brightness triggers a number of beam dynamics and technical challenges. Ring parameters such as energy, circumference, lattice, momentum compaction, bending and super-conducting wiggler fields are carefully chosen in order to provide the target emittances under the influence of intrabeam scattering but also reduce the impact of collective effects such as space-charge and coherent synchrotron radiation. Mitigation techniques for two stream instabilities have been identified and tested. The low vertical emittance is achieved by modern orbit and coupling correction techniques. Design considerations and plans for technical system, such as damping wigglers, transfer systems, vacuum, RF cavities, instrumentation and feedback are finally reviewed.  
 
TUPPD016 Collection Optics with the Horn Type Focusing Element made with Separate Conductors focusing, secondary-beams, optics, scattering 1443
 
  • A.A. Mikhailichenko
    CLASSE, Ithaca, New York, USA
  
  We describe the device for focusing of charged particles by the system of separated conductors which follow the parabolic profile. Basically this is a horn-type focuser, but with the individual conductors instead of continuous surface. This device allows substantial reduction of fabrication cost with the same focusing properties as the continuous parabolic surface. We recommend this “bird-cage” type system for focusing pions/muons in the projects under discussion in many Laboratories around the World.  
 
TUPPD024 HIGH-INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON LABORATORY target, simulation, solenoid, radiation 1461
 
  • S. Golge, B. Vlahovic
    NCCU, Durham, USA
  • B. Wojtsekhowski
    JLAB, Newport News, Virginia, USA
  
  We present a novel concept of a low-energy e+ source with projected intensity on the order of 1010 slow e+/s. The key components of this concept are a continuous wave e- beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e+ into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.  
 
TUPPD025 REVIEWOF LOW-ENERGY POSITRON BEAM FACILITIES target, linac, neutron, radiation 1464
 
  • S. Golge, B. Vlahovic
    NCCU, Durham, USA
  
  Positrons are produced by processes such as positive beta decay from radioactive isotopes, in nuclear reactor cores from both in-situ radioisotope radiation and pair production, and by accelerator driven beams hitting a converter target. The purpose of this paper is to review some of the prominent existing low-energy e+ facilities.  
 
TUPPD032 Design Optimization of Flux Concentrator for SuperKEKB solenoid, simulation, target, electron 1473
 
  • L. Zang, S. Fukuda, T. Kamitani, Y. Ogawa
    KEK, Ibaraki, Japan
  
  For high luminosity electron-positron colliders, intense positron beam production is one of the key issues as well as electron. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will discuss a design optimization of a FC for the SuperKEKB positron source. Geometrical parameters of the FC are optimized to achieve high peak field using the CST EM Studio. Magnetic field distribution evaluated with the EM Studio is implemented into a particle tracking code to see a performance of the positron capture section. The tracking simulation includes a positron production at the target, focusing by the FC and subsequent solenoids and acceleration by RF structures till the end of the capture section. We report the results of a FC design optimized for higher positron yield with the tracking simulation.  
 
TUPPD033 Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays target, photon, dipole, electron 1476
 
  • R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa
    Muons, Inc, Batavia, USA
  • A. Afanasev
    GWU, Washington, USA
  
  A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.  
 
TUPPD036 Novel Designs for Undulator Based Positron Sources target, undulator, photon, damping 1485
 
  • M. Jenkins
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • I.R. Bailey, M. Jenkins
    Lancaster University, Lancaster, United Kingdom
  
  At least three proposed future colliders(ILC, CLiC and LHeC) require a positron source with a yield greater than 1014 e+/s. An undulator based positron source has the potential to provide the required yield. This design generates gamma rays by using a high energy electron beam traveling through a superconducting helical undulator. The gamma rays then pair produce in a titanium alloy target to produce positrons. This is the ILC baseline positron source. Two drawbacks to the undulator-based positron source are that it couples the positron source to the electron beam operation and that it exhibits a low conversion efficiency of photons to positrons. A self-seeding undulator-based positron source has been proposed. This starts with a low intensity positron beam which travels through the undulator to produce more positrons which are recirculated through the source to increase the intensity until the design yield is achieved. Multiple targets have been added to increase the conversion efficiency of the positron source. In this study I present simulation results for such a design and consider the feasibility of this design at the ILC, CLiC or LHeC.  
 
TUPPP092 Renovated Two-stage Bunch Compressor for the International Linear Collider wiggler, linac, linear-collider, collider 1801
 
  • S. Seletskiy
    BNL, Upton, Long Island, New York, USA
  • N. Solyak
    Fermilab, Batavia, USA
  
  The International Linear Collider (ILC) utilizes a Bunch Compressor (BC) in the Damping Ring to Main Linac Transfer Line (RTML) that compresses the RMS bunch length from 6 mm to 300 micrometers before sending the beam to the Main Linac. It was decided to utilize a two stage BC for the design baseline, since it provides an additional option for the ILC to work with 150 micrometers long bunches and reduces the energy spread at the RTML exit under normal operational conditions. In this paper we report the new design of the optimized two-stage bunch compressor.  
 
TUPPR001 Spin Tracking Simulation of a Future International Linear Collider polarization, solenoid, electron, simulation 1807
 
  • V.S. Kovalenko, O.S. Adeyemi, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • A.F. Hartin
    DESY, Hamburg, Germany
  • S. Riemann, F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The full physics potential of the International Linear Collider (ILC) is expected to be optimized by using polarized electron and positron beams. To ensure that no significant polarization can be lost during the transport of the electron and positron beams from the source to the interaction region, spin tracking has to be included in all transport elements which can contribute to a potential loss of polarization. The possible sources of depolarization such as the spin rotators and the damping ring have been investigated for the current ILC baseline. The detailed spin tracking simulations and study depolarization was performed by using BMAD and SLICKTRACK computer codes. The new results of our simulations for the ILC are presented. 		 
 
TUPPR002 Simulations of Positron Polarization in the Undulator-Based Source undulator, polarization, electron, photon 1810
 
  • A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick
    University of Hamburg, Hamburg, Germany
  • A.F. Hartin
    DESY, Hamburg, Germany
  • S. Riemann, F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The generation of an intense and highly polarized positron beam is a challenge. The design for the International Linear Collider proposes a positron source based on a helical undulator located at the end of the electron linac. This design allows us to utilize a high energy linear accelerator with both electron and positron beams polarized. The polarization of the positron beam can be enhanced using a photon collimator. The optimization of positron yield and polarization for a wide energy range has been studied for different undulator parameters and collimator designs, taking into account realistic parameters for the capture section. In particular, the effects of misalignment and tolerances are considered. 		 
 
TUPPR003 The Design of Spin-Rotator with a Possibility of Helicity Switching for Polarized Positron at the ILC solenoid, damping, polarization, lattice 1813
 
  • L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, G.A. Moortgat-Pick, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • A.F. Hartin, B. List, N.J. Walker
    DESY, Hamburg, Germany
  • S. Riemann, F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: Work supported by German Federal Ministry of education and research. Joint Research project R&D Accelerator Spin Management, contract N 05H10CUE
At the ILC, positrons are produced with longitudinal polarization at the source. In order to preserve the polarization, the spin must be rotated into the vertical direction prior to injection into the damping rings. A new design of the spin rotator is presented that allows to randomly switch between the two vertical orientations between successive bunch trains. After rotating the spin back to longitudinal polarization, this corresponds to a choice between the two possible helicity states at the interaction point. The fast flipping is achieved by inserting two parallel spin rotation sections with opposite polarities, with a fast magnet that allows to choose between the sections. 		 
 
TUPPR005 Linac Upgrade in Intensity and Emittance for SuperKEKB linac, emittance, electron, alignment 1819
 
  • T. Higo, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  
  The SuperKEKB is designed to produce 40 times luminosity than that of the KEKB. In order to realize such a high luminosity, the injector linac should provide both electron and positron beams of about 4-5 nC/bunch, which is several times higher than before. In addition, their emittance requirement of the injection beam to the rings is 20 microns, which is a factor of a few tens smaller than before. The intensity and emittance of the electron beam are realized directly by developing the photo RF gun. In contrast, the positron intensity is increased by adopting a higher capture efficiency system with flux concentrator followed by large-aperture accelerators, while its emittance is reduced by a damping ring. For preserving such a low emittance of both beams toward the injection to the rings, the suppression of the emittance growth is crucial. To this end, the alignment of the accelerator components should be a few tens of microns, where we need an improvement by more than a factor 10. The beam-based alignment is definitely needed with better-resolution BPMs. In the present paper are reviewed the overall progress and perspective of the design and the associated component developments.  
 
TUPPR012 Polarized Positron Source with a Compton Multiple Interaction Point Line electron, laser, simulation, linac 1834
 
  • I. Chaikovska, O. Dadoun, P. Lepercq, A. Variola
    LAL, Orsay, France
  • R. Chehab
    IN2P3 IPNL, Villeurbanne, France
  
  Positron 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 IP 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.  
 
TUPPR040 Update on ILC Positron Source Study at ANL undulator, polarization, photon, electron 1906
 
  • W. Liu, W. Gai
    ANL, Argonne, USA
  
  As the new ILC baseline has moved the positron production to the end of electron main linac, both the drive beam energy and beamline layouts have also been changed for the positron source. Now the drive beam energy will be varying from 150GeV to 250GeV and 500GeV (for TeV upgrade) as the colliding center of mass (CM) energy changes. Systematic studies on the performance of positron source under different running scenarios have been done at ANL and the results are presented in this paper.  
 
TUPPR041 Update on ILC Positron Source Start-to-End Simulation electron, undulator, lattice, linac 1909
 
  • W. Liu, W. Gai
    ANL, Argonne, USA
  
  As a result of the changes in the new ILC base line, there are many changes in the positron source beamline layouts and thus a new lattice design is required. According to the changes in the ILC baseline, a new lattice design for the ILC positron source has been developed at ANL. In this paper, both the new ILC positron source beamline lattice and the corresponding start to end simulation results are presented.  
 
TUPPR042 On the Polarization Upgrade of ILC Undulator-based Positron Source polarization, undulator, photon, electron 1912
 
  • W. Liu, W. Gai
    ANL, Argonne, USA
  • S. Riemann
    DESY, Hamburg, Germany
  • A. Ushakov
    University of Hamburg, Hamburg, Germany
  
  The current nominal polarization for ILC undulator based positron source is 30% without photon collimators. In order to improve the effective luminosity, an upgrade of positron source with higher polarization is required. Some studies on the upgrade options have been done at both DESY and ANL, and the results are presented in this paper.  
 
TUPPR043 New Baseline Design of the ILC RTML System electron, linac, optics, damping 1915
 
  • N. Solyak, V.V. Kapin, A. Vivoli
    Fermilab, Batavia, USA
  • S. Seletskiy
    BNL, Upton, Long Island, New York, USA
  
  The new ILC baseline was proposed in 2009 (Strawman baseline - SB2009) to minimize cost of the machine and accommodate many changes made in the design of the accelerator systems. The biggest changes are made in the central area, where BDS, RTML, DR, electron and positron sources are sharing the tunnels. A new layout of the compact DR and re-location of the electron and positron sources to the main tunnel requires a new lattice design for all beamlines in this area. The lattice design was coordinated between accelerator systems and Convention Facility and Siting (CFS) group to eliminate conflicts between beamlines and satisfy construction requirements. In this paper we present a new design of the RTML electron and positron lattices in the central area and other modifications made in the RTML line to accommodate changes to the beamline layouts.  
 
TUPPR051 Development of L-Band Positron Capture Accelerating Structure with Kanthal-coated Collinear Load for SuperKEKB solenoid, cavity, damping, target 1933
 
  • F. Miyahara, Y. Arakida, T. Higo, N. Iida, K. Kakihara, T. Kamitani, S. Matsumoto
    KEK, Ibaraki, Japan
  • L. Lilje
    DESY, Hamburg, Germany
  
  In order to achieve a luminosity of 8x1035 cm-2 s-1, the SuperKEKB injector is required to provide both e+e− beams higher in intensity by a factor 4-5 than those for KEKB, and with a low emittance of about 20 um. A damping ring is used to fulfill this low emittance requirement for e+, but the intensity increase is realized by a larger yield from the conversion target to the damping ring. To this end, the L-band capture system is adopted to increase the transverse and longitudinal acceptance. The capture section consists of a Tungsten conversion target with flux concentrator followed by two L-band 2.4m-long accelerating structures and continuing to the large aperture S-band 2m-long ones. The L-band frequency of 1.3 GHz, 5/11 times S-band one, was adopted to suppress the satellite bunches in the S-band system. This L-band system is surrounded by a solenoid magnet producing 4kG on axis. To compose compact magnet system, the output coupler of the L-band accelerating structure is replaced by the Kanthal coated collinear load section. In this paper, we will discuss the design of the accelerating structure and present the studies of Kanthal layer coated on copper.  
 
TUPPR078 LEP3: A High Luminosity e+e− Collider in the LHC Tunnel to Study the Higgs Boson collider, luminosity, emittance, synchrotron 2005
 
  • F. Zimmermann, M. Koratzinos
    CERN, Geneva, Switzerland
  • A.P. Blondel
    DPNC, Genève, Switzerland
  • M. Zanetti
    MIT, Cambridge, Massachusetts, USA
  
  Recent indications from two LHC experiments suggest that the Higgs boson might be light, within the mass range 115-130 GeV. Such object could be studied at an e+e− collider with about 240 GeV centre-of-mass energy. A corresponding Higgs factory – “LEP3” - could be installed in the LHC tunnel, reducing its cost and also allowing for a second life of the two LHC general-purpose detectors. We present preliminary accelerator and beam parameters for LEP3 tailored so as to provide a peak luminosity of 1034/cm2/s at each of two experiments, while respecting a number of constraints including beamstrahlung limits. At this luminosity around 20,000 Higgs events per year per experiment could be obtained for a Standard Model Higgs boson with a mass of 115-130 GeV. For the parameters considered the estimated luminosity lifetime is about 12 minutes, and the synchrotron radiation losses are 50 MW per beam. High operational efficiency requires two rings: a low emittance collider storage ring operating at constant energy, and a separate accelerator to top up the colliding beams every few minutes. The alternative of a larger ring collider installed in a new, bigger tunnel will also be discussed.  
 
TUPPR088 Baseline Design of the SuperB Factory Injection System linac, electron, injection, emittance 2032
 
  • S. Guiducci, A. Bacci, M.E. Biagini, R. Boni, M. Boscolo, D. Pellegrini, M.A. Preger, P. Raimondi, A.R. Rossi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • M.A. Baylac
    LPSC, Grenoble, France
  • J. Brossard, S. Cavalier, O. Dadoun, T. Demma, P. Lepercq, E. Ngo Mandag, C. Rimbault, A. Variola
    LAL, Orsay, France
  • J.T. Seeman
    SLAC, Menlo Park, California, USA
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  
  The injection complex of the SuperB, B-factory project of INFN consists of a polarized electron gun, a positron production system, electron and positron linac sections, a positron damping ring and the transfer lines connecting these systems and the collider main rings. To keep the ultra high luminosity nearly constant, continuous injection of 4 GeV electrons and 7 GeV positrons in both Low Energy Ring (LER) and High Energy Ring (HER) is necessary. In this paper we describe the baseline design and the beam dynamics studies performed to evaluate the system performance.  
 
WEPPC116 Depth Distribution of Losses in Superconducting Niobium Cavities cavity, niobium, SRF, vacuum 2495
 
  • A. Romanenko, A. Grassellino, J.P. Ozelis
    Fermilab, Batavia, USA
  • H. Padamsee
    CLASSE, Ithaca, New York, USA
  
  In order to optimize performances of superconducting niobium cavities it is crucial to understand the structure of near-surface few tens of nanometers of the material. In particular, superconducting properties of niobium, which depend on the presence of impurities and/or defects, may be non-uniform in the magnetic field penetration depth. A few cavity experiments based on oxypolishing* and anodizing**,*** provided some insight into the problem, but the definitive understanding is not developed yet. In this contribution we report on the "depth profiling" of the near-surface RF layer using an alternative technique based on the hydrofluoric acid (HF) rinsing. Tumbled, electropolished and buffered chemical polished cavities have been investigated and tentative nanostructural interpretation is discussed.
* P. Kneisel, Proc. of the 1999 SRF Workshop, Santa Fe, USA
** G. Eremeev and H. Padamsee, Physica C 441 No. 1-2 (2006) 62
*** G. Ciovati, P. Kneisel and A. Gurevich, PRSTAB 10 (2007) 062002 		 
 
WEPPD032 Heat Load Studies in Target and Collimator Materials for the ILC Positron Source photon, polarization, undulator, target 2576
 
  • F. Staufenbiel, S. Riemann
    DESY Zeuthen, Zeuthen, Germany
  • O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
    University of Hamburg, Hamburg, Germany
  
  An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat load and stress inside the target and collimator materials. In order to avoid failure of these components the stress evolution has been simulated. The results as well as the corresponding material arrangements for the photon collimator design are presented.  
 
WEPPD064 Quick Recovery of the KEK e−/e+ Injector Linac from the Great East Japan Earthquake linac, vacuum, injection, electron 2669
 
  • A. Enomoto
    KEK, Ibaraki, Japan
  
  The KEK e−/e+ injector linac is under operation for the KEK Photon Factory (PF) storage ring and Photon Factory - Advanced Ring (PF-AR). And the linac has just started the upgrade for the SuperKEKB project. On March 11, the linac suffered great damage from the Great East Japan Earthquake. Due to an extraordinary strong vibration, many bellows of vacuum pipes were violently torn and the entire linac vacuum was exposed to the atmosphere. Without electricity, highly humid air entered the inside of accelerator structures. Some people supposed the linac would not be recovered within a year. However, it resumed operation after only two months. We report the memorable disaster and how we recovered the linac so quickly.  
 
WEPPP010 FACET: SLAC's New User Facility electron, acceleration, wakefield, linac 2741
 
  • C.I. Clarke, F.-J. Decker, R.J. England, R.A. Erickson, C. Hast, M.J. Hogan, S.Z. Li, M.D. Litos, Y. Nosochkov, J.T. Seeman, J. Sheppard, U. Wienands, M. Woodley, G. Yocky
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET (Facility for Advanced Accelerator Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. The first User Run started in spring 2012 with 20 GeV, 3 nC electron beams. The facility is designed to provide short (20 um) bunches and small (20 um wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. The creation of drive and witness bunches and shaped bunch profiles is possible with "Notch" Collimation. FACET is also a source of THz radiation for material studies. Positrons will be available at FACET in future user runs. We present the User Facility and the available tools and opportunities for future experiments. 		 
 
WEPPP031 To the Possibility of Bound States between Two Electrons electron, emittance, damping, proton 2792
 
  • A.A. Mikhailichenko
    CLASSE, Ithaca, New York, USA
  
  We analyze the possibility to compress dynamically the polarized electron bunch so that the distance between some electrons in the bunch comes close to the Compton wavelength, arranging a bound state, as the attraction by the magnetic momentum-induced force at this distance dominates repulsion by the electrostatic force for the appropriately prepared orientation of the magnetic moments of the electron-electron pair. This electron pair behaves like a boson now, so the restriction for the minimal emittance of the beam becomes eliminated. Some properties of such degenerated electron gas represented also.  
 
WEPPP052 Self-modulation of Long Particle Bunches in Plasmas at SLAC plasma, wakefield, electron, simulation 2831
 
  • P. Muggli
    MPI, Muenchen, Germany
  • Y. Fang
    USC, Los Angeles, California, USA
  • M.J. Hogan
    SLAC, Menlo Park, California, USA
  • W.B. Mori
    UCLA, Los Angeles, California, USA
  • L.O. Silva, J. Vieira
    IPFN, Lisbon, Portugal
  
  The transverse self-modulation (SM) of ultra-relativistic, long particle bunches can lead to the generation of large amplitude wakefields*. In this work we show that the physics of SM could be investigated with the long electron and positron bunches available at SLAC**. The propagation of SLAC electron and positron bunches in 1 meter plasmas was modeled with OSIRIS. 3D simulations reveal that hosing may limit SM, but that shaped bunches with a hard-cut front ensure that saturation of SM can be reached. Cylindrically symmetric simulations show that the blowout regime can be achieved using these shaped bunches. Accelerating gradients in excess of 20 GeV/m are generated, and up to 10 GeV energy gain and loss are observed in the simulations at the 1% charge level after one meter of plasma. Because the blowout regime is reached, positron driven wakes lead to accelerating gradients that can be less than half than those of electrons. Simulations results outlining the SM results expected with the SLAC-FACET beam parameters will be presented.
* N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010).
** J. Vieira et al., submitted (2011). 		 
 
WEPPP056 Positron PWFA Simulations for FACET plasma, simulation, focusing, electron 2834
 
  • S.J. Gessner, E. Adli, S. Corde, R.J. England, J.T. Frederico, M.J. Hogan, S.Z. Li, M.D. Litos, T.O. Raubenheimer, D.R. Walz, Z. Wu
    SLAC, Menlo Park, California, USA
  • W. An, W.B. Mori
    UCLA, Los Angeles, California, USA
  
  Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
When a positron beam enters a plasma, plasma electrons are drawn in toward the beam axis, creating a region of extremely large charge density with complicated, nonlinear fields. Few analytic solutions exist to describe these fields, and this necessitates the use of simulations to model positron beam and plasma interactions. This presentation should cover recent work on positron PWFA simulations using the QuickPIC* particle-in-cell code. I will discuss the computational challenges associated with positron PWFA and specific applications of the simulations for future experimental tests at the FACET user facility at SLAC.
* C. Huang et al., "QuickPIC: A highly efficient particle-in-cell code for modeling wakefield acceleration in plasmas," J. Comp. Phys. 217, 658 (2006). 		 
 
WEPPR015 Intrabeam Scattering Studies at CesrTA emittance, scattering, electron, lattice 2970
 
  • M. P. Ehrlichman
    Cornell University, Ithaca, New York, USA
  • F. Antoniou, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • W. Hartung, M.A. Palmer, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, C.R. Strohman, S. Wang
    CLASSE, Ithaca, New York, USA
  • R. Holtzapple
    CalPoly, San Luis Obispo, California, USA
  
  Funding: NSF Award (PHY-0734867) NSF Award (PHY-1002467) Japan/US Cooperation Program Education and lifelong learning, co-financed by Greece and the European Union
Intrabeam scattering dilutes the emittance of low energy, low emittance rings. Because CesrTA can be operated at low energies with low transverse emittances and high bunch intensity, it is an ideal laboratory for the study of IBS effects. Furthermore, CesrTA is instrumented for accurate beam size measurements in all three dimensions, providing the possibility of a complete determination of the intensity dependence of emittances. Models based on classical IBS theories and multi-particle simulations are used to estimate the effect of IBS at CesrTA at different beam emittances, intensities and energies. The first measurements from machine studies at CesrTA are presented. 		 
 
WEPPR076 Positron Options for the Linac-ring LHeC target, emittance, electron, laser 3108
 
  • F. Zimmermann, O.S. Brüning, Y. Papaphilippou, D. Schulte, P. Sievers
    CERN, Geneva, Switzerland
  • H.-H. Braun
    Paul Scherrer Institut, Villigen, Switzerland
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • L. Rinolfi
    JUAS, Archamps, France
  • A. Variola, Z.F. Zomer
    LAL, Orsay, France
  • V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  
  The full physics program of a future Large Hadron electron Collider (LHeC) requires both pe+ and pe- collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8·1015 or 4.4·1016 e+/s at the collision point, which is about 300 or 7000 times the past SLC rate. We consider providing this e+ rate through a combination of measures: (1) Reducing the required production rate from the e+ target through colliding e+ (and the LHC protons) several times before deceleration, by reusing the e+ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, sliced-rod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coherent pair production in a strong laser, or high-field undulator radiation from the high-energy lepton beam. We describe the various concepts, present example parameters, estimate the electrical power required, and mention open questions.  
 
WEPPR087 Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA Due to Variations in Chromaticity, Bunch Current and Train Length betatron, electron, feedback, emittance 3135
 
  • M.G. Billing, G. Dugan, M.J. Forster, D.L. Kreinick, R.E. Meller, M.A. Palmer, G. Ramirez, M.C. Rendina, N.T. Rider, J.P. Sikora, K.G. Sonnad, H.A. Williams
    CLASSE, Ithaca, New York, USA
  • J.Y. Chu
    CMU, Pittsburgh, Pennsylvania, USA
  • J.W. Flanagan
    KEK, Ibaraki, Japan
  • R. Holtzapple, M. Randazzo
    CalPoly, San Luis Obispo, California, USA
  
  Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467.
Electron cloud-induced beam dynamics is being studied at CESRTA under various conditions. These measurements detect the the coherent self-excited spectrum for each bunch within a train and bunch-by-bunch beam size. In the position spectrum coherent betatron dipole and head-tail motion is detectable for each individual bunch within the train with a sensitivity for the motion of 1.1 (2) microns-rms in the vertical (horizontal) direction for a 1 mA bunch current. These techniques are utilized to study the electron cloud-related interactions, which cause the growth of coherent motion and beam size along the train. We report on the observations and results from studies of the instability growth vs. changes in chromaticity, the current per bunch and the length of the train. 		 
 
THEPPB012 Pressure Acoustic Waves in Positron Production Targets for Future Lepton Colliders target, photon, collider, linear-collider 3257
 
  • O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • A.F. Hartin
    DESY, Hamburg, Germany
  • F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
  
  Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
Future high energy lepton colliders demand high luminosities to achieve its physics goals. For the electron-positron linear collider, the generation of positrons is a non-trivial problem: the positron production target has to a survive huge amount of energy deposited by the bombardment of intense beams of electrons or photons. This causes a rapid increase of the temperature in the target within a very short time period. The resulting thermal stress induces pressure waves and can substantially shorten the operating life-span of for the target material. In this work, we study linear and effects of induced stress through pressure acoustic waves using a hydrodynamic model. The survivability issue of the target is discussed. 		 
 
THPPR057 Feasibility Study Gamma-induced Positron Annihilation Lifetime Spectroscopy in an Electron Storage Ring laser, electron, target, storage-ring 4103
 
  • Y. Taira, H. Toyokawa
    AIST, Tsukuba, Ibaraki, Japan
  • M. Adachi, M. Katoh, S. Tanaka
    UVSOR, Okazaki, Japan
  • N. Yamamoto
    Nagoya University, Nagoya, Japan
  
  Funding: This work was supported by Grants-in-Aid for Scientific Research (22360297) and Grant-in-Aid for JSPS Fellows (235193).
Positron annihilation lifetime spectroscopy (PALS) has proved to be very sensitive tool to characterize materials and study defects. However PALS has been restricted to thin samples because of the limited range of positrons in materials. We have developed new techniques for PALS, in which laser Compton scattered (LCS) gamma rays are used to produce positrons inside materials via pair production. Ultra-short gamma ray pulse source* with pulse width of 5 ps (FWHM) generated by 90-degree collision LCS was applied to PALS for the first time. The short pulse width of the gamma-rays that is negligible compared to estimated positron lifetime (100 ps to ns range) is essential to PALS. The experiment was carried out at the UVSOR-II electron storage ring, a 750 MeV synchrotron light source. The positron annihilation lifetime, 199 ± 10 ps, in a bulk sample of lead was successfully measured by using the ultra-short gamma ray pulse.
* Y. Taira, et al., Nucl. Instr. And Meth. A 637 (2011) S116.