Calibration and cross-laboratory implementation of scintillating screens for electron bunch charge determination

In this article we revise the calibration measurements of different scintillation screens commonly used for the detection of relativistic electrons, extending previous reference work towards higher charge density and new types of screens. Electron peak charge densities up to 10 nC/mm² were provided by focused picosecond-long electron beams delivered by the ELBE linear accelerator at the Helmholtz-Zentrum Dresden-Rossendorf.
At low charge densities, a linear scintillation response was found, followed by the onset of saturation in the range of nC/mm². The absolute calibration factor (photons/sr/pC) in this linear regime was measured to be almost a factor of 2 lower than reported by Buck et al. retrospectively implying a higher charge in charge measurements performed with the old calibration. A good agreement was found with the results by Glinec et al.. Furthermore long-term irradiation tests with an integrated dose of approximately 50 nC/mm² indicate a significant decrease of the scintillation efficiency over time.
Finally, in order to enable the transfer of the absolute calibration between laboratories, a new constant reference has been developed.