LSC and unexplained luminescence

["M. Woo" <m-woo@uiuc.edu>]

Here's a puzzler...

In the past couple of weeks, we've been getting very high (sometimes
70-80%!) luminescence readings on our liquid scintillation counter
readouts... using *blank* samples as well as "real" samples.  Holding
the LSC vials and recounting after a day reduces the luminescence to
acceptable levels, so the problem is presumably not the LSC itself.

The blank I made up last year is fine (<0.2% luminescence).  We have
tried changing the scint fluid using a bottle from another lot #, as
well as wiping the outside of the vials with water-moistened wipes and
anti-static wipes to reduce any static buildup to no avail.  Actually,
now that I'm thinking about it, we should probably try opening up a new
flat of vials to eliminate them as a possibility.

At this point, we're willing to accept aliens as the cause. :-) 
However, suggestions from RADSAFErs with more experience would be
greatly appreciated.

Thanks in advance!  My e-mail address should be below in my .sig.

-- 
Melissa Woo, Health Physicist <mailto:m-woo@uiuc.edu>
Div. of Environmental Health & Safety
101 S. Gregory St., MC-225, Urbana, IL 61801
office	217.244-7233 fax 217.244.6594 <www.uiuc.edu/ph/www/m-woo/>
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