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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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