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Re: Isotopes in natural environment
Hmmm, the branching ratio to Tl-210 is pretty small (0.02%), so I don't
think you would have much of a chance of seeing it in a body counter. Even
if there was some Tl-210, the 670 and 1592 lines are really weak (2% each
according to http://atom.kaeri.re.kr/cgi-bin/decay?Tl-210+B- ).
The 1592.7 line sounds more like the 2614.5 Tl-208 line with both
annihilation photons missing. (2614.5 keV photon hits detector, produces
electron - positron pair. Electron and positron deposit their kinetic energy
(1592.5 keV) in the detector. Positron annihilates with local electron and
produces two 511 keV photons, which can escape the detector without
depositing energy.) Tl-208 is a Thoron daughter and there should be lots of
it in peoples' lungs. The 2614.5 line has 100% intensity.
Regards,
Kai Kaletsch
Environmental Instruments Canada Inc.
http://www.eic.nu
----- Original Message -----
From: "William V Lipton" <liptonw@DTEENERGY.COM>
To: "LAM HOI CHING" <lamhc@HKUSUA.HKU.HK>
Cc: <radsafe@list.vanderbilt.edu>
Sent: Monday, June 03, 2002 5:33 AM
Subject: Re: Isotopes in natural environment
> Here are some possibilities, which I sometimes pick up on gamma
spectrometry
> blanks:
>
> 670.4 kev and 1592.7 kev: Tl-210, part of the U-238 decay chain
> 911.5 kev: Ac-228, part of the Th-232 decay chain.
>
> The opinions expressed are strictly mine.
> It's not about dose, it's about trust.
> Curies forever.
>
> Bill Lipton
> liptonw@dteenergy.com
>
>
> LAM HOI CHING wrote:
>
> > Dear radsafers,
> > Several peaks have been detected in the whole body counter, but some
of
> > the peaks I can't identify it now, could anybody give me the anwers.
> > Thank you.
> >
> > Recorded peak in whole body counter by Ge detector
Isotope
> > ----------------------------------------------------------------------
> > ------------
> > 352.2 keV
> > Pb-214 ( Ra B)
> > 609.4keV
> > Bi-214 (Ra C)
> > 1764.4keV
> > Bi-214 (RaC)
> >
> > 670.4keV
> > unknown
> > 911.5keV
> > unknown
> > 1592.7keV
> > unknown
> >
> > I search those peaks in the following website but there are too plenty
> > possibilities
> > http://nucleardata.nuclear.lu.se/Scripts/database/nudat/Gamma.idc
> >
> > Could anybody give me advice on this? Thank you
> >
> > John Lam, Physicist, Eastern Hospital, Hong Kong
> >
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