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Re: GM pancake "wipe counter"
- To: radsafe@romulus.ehs.uiuc.edu
- Subject: Re: GM pancake "wipe counter"
- From: Robert J Wilson <RWILSON@utmem1.utmem.edu>
- Date: Wed, 23 Feb 2000 16:34:43 -0600 (CST)
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- Posting-date: Wed, 23 Feb 2000 16:34:44 -0600 (CST)
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- UA-content-id: C85IIN3KGES
The least efficiency for radionuclides in NM is probably for Tc-99m
For a DRY WIPE (so nothing goes into the wipe)+
N0THING OVER THE THIN WINDOW OF THE PANCAKE PROBE (so that the particulate
radiation from Tc-99m can get through the window)=
an efficiency of 2-3% (you should check this with a DRY Tc-99m standard!)
.02 X 2200 dpm = 44 cpm , which you might get in the counting mode, say for 10
minutes
BUT 49?CFR allows 300 cm**2???? wipe
so .02 X 6600 dpm = 132 cpm, which you might get even in rate mode
rwilson@utmem.edu
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