DESY, in collaboration with the ESRF, and Instrumentation Technologies, has developed beam position monitors (BPM), with a position resolution better than 50 nanometers. The first systems are for small monochromatic focused beams, close to the sample. Since space around the sample is limited and precious the devices have to be thin. They should absorb only a small fraction of the incident flux, while still giving enough signal in order to be able to measure small beam movements, at a few tens of hertz.
Single crystal diamonds are the best candidates to fulfill these requirements. They are near perfect, very homogeneous, fast, low-Z, and both thermally and mechanically very robust. A four-quadrant Single-Crystal Diamond, coupled to a modified Libera Brilliance RF readout is depicted below.
These four-quadrant diamond detectors are connected to RF-based electronics, based on the Libera electron BPM modules. This gives the possibility to achieve very low noise performance. The pictures below show results obtained at the F4 beamline at DORIS where an attenuated white beam of 20um x 20um was used and the quadrant BPM scanned as indicated in the inset.
Project Leader: Heinz Graafsma