Single crystal CVD diamond as an X-ray beam monitor

Synchrotron X-ray beams may now be focussed to < 1 μm and devices with similar spatial precision are required to monitor the beam position or provide real-time information for position control. Over the X-ray energy range 5-25 keV, diamond is an outstanding material for the fabrication of'semitransparent' beam monitors. Tests were made at the ESRF with 'electronic grade', single crystal diamond samples which were patterned with metal contacts and operated as solid-state ionization chambers. A uniform spatial response flat within 0.2% was seen when the devices were mapped with a sub-micron synchrotron X-ray beam, and the photoelectric current generated was linear with the beam intensity and showed no time lag effects. The beam induced currents were measured both at DC and at the RF frequency of the synchrotron. A sensitivity of <13 nm to beam movement was obtained.