Photo peak duplication when the source is on the side of the scintillator

[Richard]

Hi Karl and Steve, encouraged by your advice I ordered a new crystal on eBay. Lets hope it is OK and that the swedish customs let it pass without excessive taxes and import charges. Karl, it is very kind of you to offer to help me. It's a pity that you move from Stockholm. Your suggestion of coupling grease sounds as an interesting alternative to Selley's "All Clear" glue. I am a bit worried about how to separate the old crystal and get rid of all glue residue without damaging the PMT. Steven, do you know if aceton or etanol is a good solvent? Anyway, I have to postpone the repair to some later time since now my vacation is at end.

Thanks Steve for sharing the spectra of your broken crystal. Your spectra differs a bit from mine. In your spectra the ghost peaks are shifted to higher energy while in my spectra, they are shifted to lower energy compared with the peaks at pure front illumination. Maybe it depends on the two volumes of the fractured parts.

[Sesselmann]

Richard,

I am not sure what kind of solvent would dissolve Selleys all clear, Selleys might offer advise, otherwise I can experiment with a few different solvents when I get back home from my vacation in a week.

Acetone should work fine, at least for removing any glue from the glass.