Transmissive Imaging X‐Ray Beam Position Monitors (XBPM) for Protein Crystallography (PX) Beamlines

We present the development of transmissive imaging X‐ray Beam Position Monitors (XBPM) for use in Protein Crystallography (PX) beamlines and beamlines operating at photon energies around and above 10 keV and fluxes of 1010 photons/s or higher. Results from different phosphors, substrates and coating techniques are compared with respect to transmission, layer quality and image resolution. The screen absorption is below 10 % for selected phosphors at photon energies above 10 keV. This enables continuous monitoring of both beam shape and intensity during experimental data collection at a few micron resolution. The screens have been designed for monochromatic beams, with a maximum beam diameter of 2 mm (extendible to 25 mm). The presented approach not only promises a generic solution for use in the automation of PX beamlines, but will also be extendible to other state‐of‐the‐art crystal monochromator beamlines.