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Photomultiplier - Cherenkov detector success! - soldering questions

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Kleinstein:
Congratulations :-+   :clap:

Are the observed peaks really related to the plastic block ? At enough voltage and thus very high gain the PMT can also see single Photons / dark emissions as separate peaks. So one should to the test if the signal is there even without the plastic block. It is still not sure the light pulses are  Cherenkov radiation or scintillation.

jmelson:

--- Quote from: Kleinstein on February 14, 2020, 08:43:25 pm ---Congratulations :-+   :clap:

Are the observed peaks really related to the plastic block ? At enough voltage and thus very high gain the PMT can also see single Photons / dark emissions as separate peaks. So one should to the test if the signal is there even without the plastic block. It is still not sure the light pulses are  Cherenkov radiation or scintillation.

--- End quote ---
Dark current from the PMT photocathode will be almost totally uniform (at any specific HV setting).  Pulses from various environmental radiation (mostly cosmic ray showers) will vary in energy.
So, that's one way to be pretty sure you are seeing real radiation.  Then, of course, if you can come up with some kind of source (potassium salt, a chip of an old Corelle orange plate with
U235 glaze, or whatever you might have around) you can move it closer or farther.

Jon

ChristofferB:
Thanks!! I'm pretty hyped about it!

I'm not completely convinced what I'm looking at yet either, and I want to build a proper current to voltage preamp before playing around with the scintillators/cherenkov detectors.

I've also read that a lot of things scintillates, albeit inefficiently, and it is not oncommon to see glass scintillation from the PMT envelope itself.

I did try putting the pmt anode signal directly into my shaping amplifier, giving some much nicer peaks, see attached.

I'm not a big fan of this solution, though, signal quality aside, i'd REALLY like having something 'expendable' inbetween my main spectroscopy rack and my detector, in case I mess something up with the HV.

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