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

• Published in: Review of scientific instruments 2008-06, Vol.79 (6)
• Main Authors: Fuchs, Martin R., Holldack, Karsten, Erko, Alexei, Schaefers, Franz, Mueller, Uwe, Bullough, Mark, Walsh, Susanne, Wilburn, Colin
• Format: Article
• Language: English
• Subjects: BEAM POSITION; BESSY STORAGE RING; CENTER-OF-MASS SYSTEM; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; KEV RANGE; KHZ RANGE; MONITORS; MONOCHROMATIC RADIATION; MONOCHROMATORS; PHOTONS; POSITION SENSITIVE DETECTORS; RADIATION DETECTION; RING CURRENTS; THICKNESS; TIME RESOLUTION; X RADIATION
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.2938400

We present the development of fast transmissive center-of-mass x-ray beam position monitors with a large active area, based on a thinned position sensitive detector in both a duo- and a tetra-lateral variant. The detectors were tested at BESSY beamlines BL14.1, KMC-1, and KMC-2 and yielded signal currents of up to 3 {mu}A/100 mA current at 10 keV photon energy using the monochromatic focused beam of BL14.1. The active area sizes were 1x1 and 3x3 mm{sup 2} for the duo-lateral and 5x5 mm{sup 2} for the tetra-lateral devices, with the duo-lateral detectors currently being available in sizes from 1x1 to 10x10 mm{sup 2} and thicknesses between 5 and 10 {mu}m. The presented detectors' thicknesses were measured to be 5 and 8 {mu}m with a corresponding transmission of up to 93% at 10 keV and 15% at 2.5 keV. Up to a detection bandwidth of 10 kHz, the monitors provide submicron position resolution. For lower detection bandwidths, the signal-to-noise reaches values of up to 6x10{sup 4} at 10 Hz, corresponding to a position resolution of better than 50 nm for both detector sizes. As it stands, this monitor design approach promises to be a generic solution for automation of state-of-the-art crystal monochromator beamlines.