Re: Dosimetry

[denison.8@osu.edu]

Sandy Perle wrote:

>Jim Abraham correctly assessed that the following statement is
>unfounded.
>
>> > Also consider the fact that quarterly TLD's have to be more stable and
>> > better able to "hold a dose" over a long period of time than monthly ones.
>> > This probably means that the TLD and supporting materials are more
>> > expensive than stuff that only has to last a month.
>
>In actuality, the TLD is stable for any time period. The only
>technical requirement is that the appropriate fade factor correction
>be used for the length of time the badge was in the field. The fade
>reaches equillibrium in about 120 days, therefore, after that time,
>there is no change in fade correction applied.

Mea culpa.  I guess that's what I get for doing e-mail after midnight.  I
obviously projected some of the shortcomings of the chemical dosimeters I'm
studying onto TLD's.  I wasn't aware that the fade levels off so cleanly
with TLD's (some of the chemical systems I've examined can continue to
"lose dose" over a period of months, apparently due to recombination and/or
chemical equilibrium effects).  Sorry.  Should have phrased that part as a
question (i.e. 'Do they have to be more durable?')

I'll stand by the calculations, though, and stress that none of this was
ever meant as an "attack" against anyone.  Just an airing of potentially
overlooked factors.  Peace.


J. Eric Denison
Nuclear Engineering Program
The Ohio State University
2030 Robinson Laboratory
206 West 18th Avenue
Columbus OH 43210
(614) 292-3681 or -1074
denison.8@osu.edu


************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html