Author: Strokov, S.A.
Paper Title Page
TUPP011 Observation of Scintillators Charging Effects at the European XFEL 303
  • A.I. Novokshonov, B. Beutner, G. Kube
    DESY, Hamburg, Germany
  • S.A. Strokov
    TPU, Tomsk, Russia
  Scintillating screens are widely used for beam profile diagnostics at various kinds of particle accelerators. At modern linac based electron machines with ultrashort bunches as the European XFEL in Hamburg (Germany), scintillators help to overcome the limitation of standard OTR based monitors imposed by the emission of coherent radiation. The XFEL injector section is equipped with four off-axis screens allowing to perform online beam profile diagnostics, i.e. a single bunch out of a bunch train is kicked onto the screen and the profile is analyzed. However, during user operation a decrease of the SASE level was observed in cases that one of the of-axis screens was used. The observation is explained by charging of the scintillator screen: each deflected bunch hitting the screens causes ionization and charging of the screen. The scintillator as good insulator keeps the charge for some time such that the non-deflected part of the bunch-train feels their Coulomb force and experiences a kick, resulting in a drop of the SASE level. This report summarizes the observations at the European XFEL and introduces a simple model for quantification of this effect.  
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About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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