Keyword: polarization
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MOPB16 Continuous Beam Energy Measurements at Diamond Light Source beam-losses, operation, wiggler, resonance 107
 
  • N. Vitoratou, P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  • P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  Resonant Spin Depolarization (RSD) is a well-known technique that has been employed by Diamond Light Source (DLS) for beam energy measurements. In this project, we study a new approach to make RSD compatible with user beam operation and provide a continuously updated online measurement. An array of four custom-made scintillation detectors has been installed around the beam pipe, downstream of collimators to capture the highest fraction of lost particles and maximize the count rate. The excitation is gated to half of the stored bunches and the acquisition system counts losses in both halves independently. Using the count in the un-excited part for normalisation suppresses external factors that modify the loss rate. Different parameters of the measurement, like excitation kick strength and duration have been explored to optimise depolarisation and to increase the reliability of the measurement.  
poster icon Poster MOPB16 [3.136 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-MOPB16  
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WEOA02 Optical Investigation to Minimize the Electron Bunch Arrival-time Jitter Between Femtosecond Laser Pulses and Electron Bunches for Laser-Driven Plasma Wakefield Accelerators laser, plasma, electron, ECR 332
 
  • S. Mattiello, A. Penirschke
    THM, Friedberg, Germany
  • H. Schlarb
    DESY, Hamburg, Germany
 
  Funding: The work of S. Mattiello is supported by the German Federal Ministry of Education and Research (BMBF) within the Project ' MAKE-PWA.
In a laser driven plasma based particle accelerators a stable synchronization of the electron bunch and of the plasma wakefield in the range of less than 2 fs is necessary in order to optimize the acceleration. For this purpose we are developing a new shot to shot feedback system with a time resolution of less than 1 fs. As a first step, stable THz pulses are generated by optical rectification of a fraction of the plasma generating high energy laser pulses in a nonlinear lithium niobate crystal. It is planed that the generated THz pulses will energy modulate the electron bunches shot to shot before the plasma to achieve the time resolution of 1 fs. In this contribution we systematically investigate the influence of the optical properties as well as the theoretical description of the THz generation on the conversion efficiency of the generation of short THz pulses in undepleted approximation. We compare different approximations for the modeling of the generation dynamics and of the dielectric function in order to investigate the importance of a detailed description of the optical properties. First results by considering intensity decreasing of the laser pump will be presented.
*The feedback system will be tested at the Accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY).
 
slides icon Slides WEOA02 [1.605 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOA02  
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WEPB14 Recent Results on Non-invasive Beam Size Measurement Methods Based on Polarization Currents radiation, target, experiment, photon 464
 
  • S. Mazzoni, M. Bergamaschi, O.R. Jones, R. Kieffer, T. Lefèvre, F. Roncarolo
    CERN, Geneva, Switzerland
  • A. Aryshev, N. Terunuma
    KEK, Ibaraki, Japan
  • L.Y. Bartnik, M.G. Billing, J.V. Conway, M.J. Forster, Y.L.P. Fuentes, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.V. Bleko, A.S. Konkov, A. Potylitsyn
    TPU, Tomsk, Russia
  • L. Bobb
    DLS, Oxfordshire, United Kingdom
  • P. Karataev, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
 
  We present recent results on non-invasive beam profile measurement techniques based on Diffraction Radiation (DR) and Cherenkov Diffraction Radiation (ChDR). Both methods exploit the analysis of broadband electromagnetic radiation resulting from polarization currents produced in, or at the boundary of, a medium in close proximity of a charged particle beam. To increase the resolution of DR, measurements were performed in the UV range at a wavelength of 250 nm. With such configurations, sensitivity to the beam size of a 1.2 GeV electron beam below 10 um was observed at the Accelerator Test Facility (ATF) at KEK, Japan. In the case of the ChDR, a proof of principle study was carried out at the Cornell Electron Storage Ring (CESR) where beam profiles were measured in 2017 on a 5.3 GeV positron beam. At the time of writing an experiment to measure the resolution limit of ChDR has been launched at ATF where smaller beam sizes are available. We will present experimental results and discuss the application of such techniques for future accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB14  
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