False Positive Betas

["STUART M. TORF (203)665-5000 x5814" <TORFSM@NU.COM>]

First of all, I want to thank everyone for all the responses on "false 
positives". 
It is forums like RADSAFE that are most useful (Thank You, Melissa).

It was apparent that I should have provided a lot more information than 
what was in my original e-mail. My apologies. Well here it is.

We use a Harshaw 8810 TLD card.

Approximately < 1% of our TLDs come up with a "false positive"

The beta chip #3 is 3.6 mil thick Li7F with a black mylar window 
(17 mg/cm2).

We use a "minimum reportable dose" algorithm which gives us a 90% 
confidence level on our beta responses. In essence, we don't see 
any betas unless they are > 200 mrem.

Our background response (chip #3) for the site in question is 
calculated (linear) (approx. 0.2 mrem/day) with an estimated error 
of  45%.

The typical beta to gamma dose ratio is anywhere from 2 to 3. Gamma 
doses are usually > 100 mrem.

The glow curves are analyzed (and in some cases smoothed out by 
glow curve refit/ analysis software) and appear normal in every 
respect. (no anomalous peaks or oddball glow curve shapes were 
identified).

Once again, thank you for all of your responses.

Stu Torf
Northeast Utilities
torfsm@nu.com