Re: Inteference correction for different energy Beta

[Laurie Taylor <laurie-taylor@uiowa.edu>]

Mr. Jo:

Re:  Pb-210 - it decays to Bi-210 which has a half-life of 5.013 days and
is in equilibrium with the Pb-210.  B-210 decays by 100% beta emission with
a maximum energy of 1.161 MeV.  Therefore, the Pb-210 source should really
be considered a Bi-210 source.  The Pb-210 source is covered with a thin
lead shield to attenuate the emissions from the Pb-210.  The lead shield
also attenuates about 10% of the emissions from the Bi-210 source and any
efficiency determined for this source should be increased by 10%.  (Note:
the other sources in your beta source set are covered with mylar covers).

Regards,
Laurie Taylor, Health Physics Associate
The University of Iowa
laurie-taylor@uiowa.edu
319/335-8532

At 12:32 PM 10/15/98 -0500, you wrote:
>I am trying to generate a beta efficiency curves vs beta energy for commonly
>used survey meters with pan cake GM and thin end window GM. We purchased a
>calibrated beta standard which includes Pb-210 and Sr-90. Pb-210 has 61 keV
>beta, 10.8 keV x-ray, and 46.5 keV gamma. My problem is how to estimate
>Pb-210's contribution to the Bi-210 betas when the above detectors are
used. A
>similar problem exist to Sr-90 (546 keV)/Y-90 (2283 keV) beta source. I would
>like to use Y-90 as high end energy point in my graph but I am not sure
how to
>separate between two betas. I feel like contribution from both Sr/Y-90 would
>be close to 1:1 (50% contribution each) when detector is in contact with
>source. I don't feel using 1:1 ratio would be a correct way.
>
>If someone had worked out this problem, I would appreciate to know.
>
>========================================================
>Myung Chul Jo, RSO
>EH&S, Mail Stop 328
>University of Nevada, Reno
>Reno, Nevada 89557
>(702)784-4540
>(702)784-4553 fax
>
>
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