The charged particle crosses both PIN diodes, causing a coincidence. Synchrotron radiation photons, if stopped by either PIN-diode, do not cause a coincidence.
K. Wittenburg was awarded the Faraday Cup in 2000 for the design of the PIN photodiode Beam Loss Monitor and its implementation at HERA. Bergoz Instrumentation was granted a license by DESY to use Wittenburg's original development.
Very small size and low unit cost make it possible to monitor all locations where beam loss is predicted.
Vacuum quality around the storage ring can be measured based on BLM count rate.
Two PIN-photodiodes mounted face-to-face detect charges particles. Coincidence counting makes it insensitive to synchrotron radiation photons.
Spurious count very low: < 1 count in 10 seconds.
Up to 10MHz counting: dynamic range >10E8
Recovers 100ns after a hit
Choice of detector solid angle: Large PIN-diodes can be user installed
Output is a TTL compatible pulse: easy counting
Tested up to 10E8 Rads for hardness
Single particle detection efficiency PIN-photodiode surface Spurious count rate Maximum count rate Output