Ceramic Channel Electron Mutlipier (CEM)
CEM - What is that?
A Channel Elektron Multiplier (CEM) is an detector for elektrons, charged particles (ionized atoms or molecules) or ligth (photons).
A CEM has an funnel with a spiral channel at its small end. Apply to the channel high voltage. Now if a charged particle hits the funnel, it will set an electron free which gets into the channel. The electron will be accelerated by high voltage. Then it will hit the wall of the channel and release more electrons. This effect will go on until a cloud of some millions of electrons is formed at the end of the channel. This ouput puls ist strong enough to be measured with electronic amplifier.
The picture shows a multiplier from the KBL type.
| CEM KBL type with a funnel of 18mm diameter |
|resistance of the wall ||< 90 MOhm|
|plateau at||<3kV (50 counts per second)|
|dark count rate||< 0.01 counts per second|
|puls hight resulution||Delta A / A < 40%|
|max. count rate||> 20 MHz ( during our tests we got more then 50 MHz) |
|bake temperature||400oC (for a short periode)|
|storage temperature||up to 100oC|
|working preasure||max. 3*10-4 mbar|
|livetime||> 5As or 3*1012 pulses|
For other information about CEM ask firstname.lastname@example.org.
He is the person who devoloped this CEM at the Max Planck Institute for Solar System Research (MPS).