Accurate simulation of the European XFEL scintillating screens point spread function

Abstract: The European XFEL is equipped with scintillating screens as a profile measurement monitor. The scintillating material used is Gadolinium Aluminium Gallium Garnet doped with Cerium (GAGG:Ce). At most of the stations, the screen is positioned perpendicular to the electron beam, with scintillation observed at a backward angle. The scintillator thickness is usually 200 um, making the resolution worse in the plane with the angle, as it allows for the entire particle track within the scintillator to be seen. Besides, aberrations are introduced by the objective used. This study outlines an accurate simulation of the point spread function (PSF) caused by all distortions of the optical system and, in addition, a method to improve the screens resolution by including the PSF into a fitting function, assuming a Gaussian beam shape.