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

We revise the calibration of scintillating screens commonly used to detect relativistic electron beamswith low average current, e.g., from laser-plasma accelerators, based on new and expanded measure-ments that include higher charge density and different types of screens than previous work [Bucket al.,Rev. Sci. Instrum.81, 033301 (2010)]. Electron peak charge densities up to 10 nC/mm2were pro-vided by focused picosecond-long electron beams delivered by the Electron Linac for beams withhigh Brilliance and low Emittance (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf. At lowcharge densities, a linear scintillation response was found, followed by the onset of saturation in therange of nC/mm2. The absolute calibration factor (photons/sr/pC) in this linear regime was measuredto be almost a factor of 2 lower than that reported by Bucket al.retrospectively implying a highercharge in the charge measurements performed with the former calibration. A good agreement wasfound with the results provided by Glinecet al.[Rev. Sci. Instrum.77, 103301 (2006)]. Furthermorelong-term irradiation tests with an integrated dose of approximately 50 nC/mm2indicate a significantdecrease of the scintillation efficiency over time. Finally, in order to enable the transfer of the absolutecalibration between laboratories, a new constant reference light source has been developed