Reflectors in scintillators

[GigaBecquerel]

Hello!

I have an old russian 63x63 mm NaI scintillator with a few yellow spots, and I will soon get access to a dry air glovebox. So I would like to try to repair it with a mix of washing and polishing it (https://doi.org/10.1016/0168-9002(87)90900-4).
It gives readable spectra, but all the peaks have a strong tail to the left. If I fit a gaussian curve over the peak without the tail I get ~8% @ 662 keV, but with the tail it is around 12%, so I think a repair could help a lot.
The reflector of those crystals is magnesia, but I wonder how it is stuffed in there, especially in the bottom as it seems to be quite compressed. Is there some trick to it?
If anyone here has ever repaired a scintillator please report your experience here!

Lukas

[luuk]

Hi Lukas,
I repaired many Russian detectors the magnesium oxide reflector is so compact because the detectors are 20-30 years old, the magnesium start to stick together and form a thick heavy layer, it is simply pressed by hand.
I would advice to remove this powder reflector an simply use a ptfe(Teflon) reflector more simple and it will give almost the same result.
Luuk

[GigaBecquerel]

Hi Luuk,

Thank you for the info!
It really looks like PTFE Tape is the solution for everything scintillator related :D
Is there some trick to removing the crystal from its housing or do I just dissolve the glue, take out the window and tap it until it falls out?

Lukas

[luuk]

Hi Lukas,
About 7 years ago I wrote a post about about the refurbishing some a 63x63mm I did.
I don't think I posted it on this forum but only on the old yahoo forum.
It is almost a step by step manual to refurbish these detectors.
If interested I can post it here.
Luuk

[GigaBecquerel]

Hi Luuk,
Definitely Interested!
I found many people talking about refurbishing crystals, but I have never seen anyone actually do it.
The more information I can collect before attempting it the higher the chance is that my crystal will survive ;-)

Lukas

[Svilen]

That will surely be interesting for many others (including me) too Luuk, go for it ;) I don't plan to do it, but definitely it would be nice to know more about it.
Greetings and thanks,

[luuk]

Ok guys here it is .
But please remember that this is a post from 2014 so the offer in the post is of course outdated and not valid any more.
It was posted on the Yahoo forum in 2014.
Have fun reading it.
Luuk

[GigaBecquerel]

Amazing report, the resolution is awesome!
This looks very promising, I should have everything to try that here soon.
I know that it's quite old by now, but a friend wants me to ask if you still have one of these for sale.

Luuk

[Svilen]

Great report and, as expected, great job too! Thanks, Luuk for sharing this with us!

[Sesselmann]

Luuk,

Thanks for the excellent report, very nice work and result.

Steven