Re: Day/Night background change?

["Schoenhofer" <schoenho@via.at>]

Schoenhofer
Habichergasse 31/7
A-1160 Wien
AUSTRIA
Tel./Fax: +43-1-4955308
Mobiltel.: +43-664-3380333
e-mail: schoenho@via.at

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> Von: Tom Paquette <paquette@shaman.nexagen.com>
> An: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Betreff: Day/Night background change?
> Datum: Montag, 09. Juni 1997 18:52
> 
> Radsafers,
> 	We have GM foot monitors at our restricted space exits set to
> alarm at about 3 times normal background.  There has been little in
> the way of spontaneous alarm events in the last year, except the last
> two months when security guards are encountering nighttime alarm-trips
> when no occupational workers are in the building.  This suggests
> the possibility of a nighttime background change which would increase
> the probability of a spontaneous alarm trip.  Is there a day/night
> difference in background radiation?
> 	I'm sure you can suggest other reasons why the observation of
> the alarm tripping could be being misinterpreted by me.  I'm not sure
> why I don't have more spontaneous trips with the alarm set at 3 times
> background.  This must have to do with the time constant setting on the
> Ludlum 177 (slow in our case) and the "run length" of background
> radiation events.  I'm checking unattended operations in the vicinity
> of the monitor in question.  For now we'll just set the alarm level up 
> another background increment.
> 	Thanks.  Tom.
> 
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Tom, 

I know that in a Scandinavian institute a rise of background during nights
and weekends was observed. After long investigations it was found out that
the shut off of the forced ventilation during nights and weekends was the
cause of an increase in the radon concentration in air. Could your problem
be explained by radon?

Franz