Speaker
Dr
Dieter Renker
(Paul Scherrer Institute)
Description
The working horse for the detection of photons is the photomultiplier tube (PMT)
which was invented in the RCA laboratories and became 1936 a commercial product.
It is an elaborated device but still, after 70 years, impressing improvements have
been achieved recently. PMTs however have two severe handicaps: they are very
sensitive to magnetic fields and their price is high because the complicated
mechanical structure inside the vacuum container is mostly handmade. This forced the
search for alternatives. Semiconductor devices, PIN-photodiodes, avalanche
photodiodes and recently Geiger-mode avalanche photodiodes have been developed and
have already replaced PMTs in many fields of research and will gain more ground in
the near future. Specially Geiger-mode avalanche photodiodes have a high potential
because they have high gain and need no or only a simple amplifier and they can be
produced in a standard and cost effective CMOS technique. When very large areas have
to be covered the cheapest device is probably a gaseous photomultiplier. Detectors
based on the so-called GEM foils (Gas Electron Multiplier), which allow to minimize
the harmful ion feedback, have high gain and even so a very long lifetime.
Author
Dr
Dieter Renker
(Paul Scherrer Institute)
