Transmissive x-ray beam position monitors with submicron position- and submillisecond time resolution

Area of Science:

• Instrumentation
• Synchrotron Radiation Science
• X-ray Optics

Background:

• Precise monitoring of X-ray beam position is critical for advanced experimental setups.
• Existing beam position monitors often face limitations in active area, resolution, or transmission.
• Automation of synchrotron beamlines requires robust and high-performance diagnostic tools.

Purpose of the Study:

• To develop and characterize fast transmissive X-ray beam position monitors (XBPMs) with large active areas.
• To evaluate the performance of duo- and tetra-lateral position-sensitive detectors for XBPM applications.
• To assess the potential of these monitors for automating state-of-the-art crystal monochromator beamlines.

Main Methods:

• Development of thinned position-sensitive detectors in duo- and tetra-lateral configurations.
• Testing of detectors at BESSY synchrotron beamlines (BL14.1, KMC-1, KMC-2).
• Measurement of signal currents, active area sizes, detector thicknesses, and X-ray transmission at various photon energies.

Main Results:

• Achieved signal currents up to 3 microA/100 mA ring current at 10 keV.
• Tested active areas ranging from 1x1 mm² to 5x5 mm², with duo-lateral detectors available up to 10x10 mm².
• Demonstrated detector thicknesses of 5-8 micrometers with high transmission (up to 93% at 10 keV).
• Obtained submicron position resolution up to 10 kHz detection bandwidth.
• Reached signal-to-noise ratios up to 6x10⁴ at 10 Hz, yielding better than 50 nm position resolution.

Conclusions:

• The developed transmissive XBPMs offer excellent position resolution and high signal currents.
• The large active area and high transmission make these detectors suitable for various X-ray applications.
• This monitor design presents a promising generic solution for the automation of crystal monochromator beamlines.