RE: Swipe Testing

[Eric Denison <denison.8@osu.edu>]

At 01:43 PM 9/30/97 -0500, Vince Chase wrote:
>Speaking of cotton swabs,  I found that I lost some counting efficiency 
>for low energy beta emitters (H-3 and C-14, particularly) over filter 
>papers...

I have also noticed a loss of efficiency with swabs (normally shows up as
increased H-number).  I have also noticed that counts tend to increase over
time if the vials are retained for a period of weeks or months and counted
again.  This is in contrast to the normal drop in counts due to decay and
degradation of the fluors.

I'm guessing that the low-energy emitters are being quenched while they are
bound up in the fiber mass of the swab, but that they eventually migrate
into the cocktail and "appear" in the counts later.

BTW, we also do dry paper for almost all of our wipes (exceptions being
difficult-to-reach places and wet areas).  We get the wipes in boxes of 100
from Acme.  If anyone needs the address, it's P.O. Box 444, Kingston, TN
37763.  I've got the pamphlet here somewhere...



Eric Denison <denison.8@osu.edu>
Radiation Safety Technician
Environmental Health & Safety
The Ohio State University