[ RadSafe ] Optical Couplant

[Syd H. Levine]

Anybody have any leads on the best place to purchase some optical coupling 
grease / gel for assembling PMTs and scintillation crystals?  I need a good 
grade since we do detectors for oil well logging tools and they are subject 
to temperature extremes.

Apparently the old GE G-688 is not available at this time.  Dow Corning 
Q2-3067 is available, but they want a small fortune for the stuff.  In fact, 
even the secondary sources seem to think the stuff is now worth its weight 
in gold since the last time I acquired some.  Anynbody use the Visilox (now 
made by Blue Star) product and have an opinion how it compares to the GE or 
Dow material?

A couple of ounces lasts us for years and years, and in fact we still have 
plenty of the material, but it is so old, I am supicious of its "goodness". 
I have most of a 4 oz. bottle of Q2-3067, but while it is still clear and 
the proper consistency, it has taken on a slight amber hue.  I also have an 
old bottle of Bicron material from long before the Saint-Gobain days, and it 
is still water clear, but has the consistency of stiff jello, hard to work 
with.

Thanks.

Syd H. Levine
AnaLog Services, Inc.
Phone:  (270) 276-5671
Telefax:  (270) 276-5588
E-mail:  analog at logwell.com
Web URL:  www.logwell.com