Author: Brovko, O.I.
Paper Title Page
MOPOW014 Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator 741
  • O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • S. Schreiber, M.V. Yurkov
    DESY, Hamburg, Germany
  Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW014  
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