'Crazy' scintillators
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This is some information on handling of bare scintillators that I came to
know, which I would like to share with you.

Recently there is a lot of concern about a kind of pattern on the grooved
tiles particularly of Ring 1. It was called 'glaze' so far.  Long ago, I
have made some cosmic paddles for Panjab Univ. They were eventually not
used. Recently when I looked at them, I found that they had exactly same
but more intense pattern. One was a bare paddle and the other was fully
packed into a paddle (I broke open the packing). Both had same pattern.

I tried to look into literature and web on this. One of the books
(W.R.Leo) said, "it is generally advisable to wear cotton or terylene
gloves as the body acids from one's hands can cause a cracking of plastic
(often referred to as 'CRAZE') AFTER A PERIOD OF TIME".

An article by K.F.Johnson (in Physical Review D66, 2002) said, "A
particularly fragile region is the surface which can "craze" - develop
microcracks - which rapidly destroy the capability of plastic
scintillators to transmit light by total internal reflection. Crazing is
particularly likely where oils, solvents, or FINGERPRINTS have contacted
the surface".

Surprisingly, Bicron documents donot elaborate much about this. One of
their documents on Handling and Cleaning Plastic Scintillators says, "When
handling bare scintillator, wear clean soft cotton gloves. IF THIS IS NOT
POSSIBLE, wash your hands to remove any oils. The normal body oils of SOME
people can damage the scintillator".