Ceramic Channel Electron Mutlipier (CEM)

	CEM - What is that?
	Technical Information

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.

Technical Information

The picture shows a multiplier from the KBL type.

Data sheet

CEM KBL type with a funnel of 18mm diameter
resistance of the wall	< 90 MOhm
plateau at	<3kV (50 counts per second)
amplification	4*10⁷
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	400^oC (for a short periode)
storage temperature	up to 100^oC
working preasure	max. 3*10^-4 mbar
livetime	> 5As or 3*10¹² pulses
shocks	> 100g

For other information about CEM ask lauche@linax1.dnet.gwdg.de. He is the person who devoloped this CEM at the Max Planck Institute for Solar System Research (MPS).

Hans Lauche
19-02-2002