Light leak

[jim-frank]

I have a Ludlum 43-9 alpha sample counter with a photomultiplier tube. I purchased it with a whole box of counters, (at a yard sale for $5, heh!) and the mylar or foil covering the scintillator was torn. My question is, is there an easy way to repair this so that I can use this fine detector head in highly variable light conditions?
I'd like to use it for various tasks, and if I can afford a neutron scintillator block, I'd like to do that.
Thanks in advance,
JIm

[guest]

You might want to try a plastics store for aluminized mylar that has a thick enough coating to be opaque, but with a thin mylar base layer. The "foil" at the business end of your alpha detector may well be mylar of this sort. The first thing I would do would be to mike it out to determine the thickness. As a desperate expedient, if the window is not too big, you might be able to get the aluminized mylar you need by tearing apart a metallized mylar capacitor.
If you are not terribly interested in keeping the probe as an alpha particle detector, you could get rid of the inner fluorescent screen and use the PMT assembly for other nefarious purposes.