Re: Calibration Standards fo

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

        Reply to:   RE>Calibration Standards for Gamma Counter

Hi Wes,

I would use the following for a NaI(Tl) based spectrometry system:

Tc-99m		0.141 MeV   ---   Co-57 0.122 (85.5%), 0.137 (10.6%)
Cr-51		0.320 MeV   ---   Ba-133 0.303 (17.8%), 0.356 (60.5%), 0.384 (8.7%)
In-111		0.171, 0.245 MeV   ---   ???-See note below   
Re-186		0.122 MeV   ---   Co-57
Re-188		0.155 MeV   ---   Co-57

I recently calibrated a 2" x 2" Well NaI(Tl) based system for In-111 by
documenting the absolute photon efficiencies for Co-57, Ba-133, Na-22,
Cs-137(Ba137m), and Co-60 and then derived a calibration factor for In-111
using the resultant curve developed for my detection system.  It was a pain to
do on an SCA system but I believe I can defend it to a regulator for
contamination survey purposes.

Hope this helps,

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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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