Dear Photomultiplier Doctor,
I have an old photomultiplier. How can I easily find out if it is in working order?
Apart from doing a visual test, there are no other tests other than electrical ones. Sometimes from
mishandling, the vacuum within the photomultiplier is compromised, in which case it will not work.
When you look at the window of the photomultiplier it should be difficult to see the internal structure
because the photocathode appears a yellow/brown colour. If this is not the case and the window looks
clear then the photocathode may be lost.
If the photomultiplier passes visual inspection then apply the HV slowly (making sure you use the correct polarity) and look on a scope for negative pulses. There should be sufficient background counts for this purpose. Do not exceed the maximum HV on the test ticket (usually less than 1300V).
Regards,
Photomultiplier Doctor.
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