Re: Old Activity Units?

["Mike Bohan" <mike.bohan@yale.edu>]

        Reply to:   RE>Old Activity Units?

Hi All,

I would put my vote in for mCi, because if the activity was in uCi the C-14
source would have been calibrated as 317.5 dpm.  If the source were in mCi
units then the calibration would be 317,460 dpm.  If the source was calibrated
in uCi, I wouldn't think it was much of a calibration standard as the counting
statistics even for a LSC would be too small, however as a mCi source it would
be in the right range.  

The easiest way to find out would to be to test it.  If they are disc type
sources, count them with a thin end window GM.  My pancake GM (HP-210L, ESP-1)
has the following efficiencies with a source to window distance of ~0.75 cm: 
Bi-210 (30%), C-14 (2.2%), Pa-234 (16.8%).  Of course, your mileage may vary,
but it will give you a ballpark number to use for a quick evaluation.

Of course, if it were MegaCuries!!!, it would blow your GM away!!!!   =%^)

<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><
Michael J. Bohan, RSO   |  e-mail: mike.bohan@yale.edu
Yale-New Haven Hospital |    Tele: (203) 785-2950
Radiological Physics    |     FAX: (203) 737-4252
20 York St. - WWW 204   |    As usual, everything I say may be plausibly
New Haven, CT    06504  |    denied at my employer's convenience ...
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--------------------------------------
Date: 22/01/97 2:26 PM
To: Mike Bohan
From: radsafe@romulus.ehs.uiuc.edu

Howdy,

We recently "found" an old set of beta reference sources with activity
units which I do not quite understand.  The date on the set is
November 1958.  The set contains:

   Bi-210   1.07 X 10^-5 MC

   C-14     14.3 X 10^-5 MC

   Pa-234   1.00 X 10^-5 MC

Any help identifying these units would be greatly appreciated.  Please 
reply to me directly.

Thanks,

Tracy

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