Diamond-based semi-transparent beam-position monitor for synchrotron radiation applications

A soft X-ray beam-position monitor based on a thin CVD diamond photodetecto r has been developed for use on third-generation synchrotron radiation faci lities, and has been tested on beamlines ID26 and ID12 at the European Sync hrotron Radiation Facility. Since diamond exhibits a low absorption to low- energy X-ray photons, this device allows beam-position monitoring with very little beam attenuation at photon energies as low as 2 keV. The devices pr esented here find their use essentially on low-energy monochromatic beamlin es with narrow beam sizes (typically below 1 mm(2)). Measurements performed on a 20 mu m-thick device show that a position sensitivity of 2 mu m can r eadily be achieved with a photon flux attenuation of 22 % at 4 keV. This al lows permanent in-situ monitoring of beam instabilities during experiments.