BPM (Single Crystal Diamond Beam Position Monitors with RF Readout Electronics)

Development of an X-ray Beam Position Monitor, based thin single-crystal diamonds, with four-quadrant electrodes and readout by modified Libera-Brilliance amplifier-filter electronics. The combination of fast diamond detectors and sophisticated signal processing at the radio-frequency of the PETRA-III ring allows for sensitivities of the beam-position down to a few tens of nano-meters, and up to frequencies of a few tens of kHz.

Single Crystal Diamond Beam Position Monitor

X and Y photon beam position with corresponding A, B, C and D quadrant mesh plots

Photon beam position (X direction in center of the sensor - 10µm x 10µm area) and it's noise (X,Y scanner back slash numerically removed)

Response to the ground shock introduced three meters away from experimental hutch

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