56926BA2, Rev. 02, 04/2019
8.3 Visual Inspection of Scintillator and Photomultiplier
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Danger to life from electric shock!
u The installation may only be carried out by a qualified electrician.
u Please adhere to the relevant safety regulations.
u Installation/maintenance may only be carried out if the device has been de
energised.
u Only open the device when free of voltage.
In case of an electric shock, carry out first aid measures and immediately call an
emergency service.
Errors on the scintillator and/or photomultiplier manifest themselves by a too small
or too steep plateau (see chapter 6.4.5). Such errors can often already be recog-
nized in a visual inspection. To do so, the scintillator and the photomultiplier must
be disassembled.
The scintillator has to be crystal clear on the inside and neither have any cracks nor
dull spots. A clear yellow to brown discolouration indicates a thermal overload and
requires replacing the scintillator.
The window of the photomultiplier has a deposited film as a photocathode. This
layer causes the window to have a slightly brownish or smoked glass colour. If this
layer is no longer present or is stained, the cathode is damaged (e.g. through over-
heating, broken glass or light). In this case, the multiplier has to be replaced.
Photomultiplier (PMT)
Scintillator
42 Representation of the Scintillator and the Photomultiplier
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