Re:: Thorium in lantern mantles

[nta@ix.netcom.com (Robert Holloway)]

You wrote: 
>
>     Bruce,
>
>     Funny you should ask a Thorium question!  While I don't know
>the  answer  to your question (and excuse me, I don't mean to  go
>off  into  another direction, but) I did recently run  across  an
>interesting "phenomenon".
>
>     I  was  doing a "show and tell" to someone using an EG&G  PC
>based  MCA  and  a  3" NaI(tl) detector and threw  in  a  thorium
>lantern  mantel  (of  unknown  age/manufacture)  and  found  some
>"interesting"  peaks.   I double checked my calibration and  they
>were  still  there in the same channels.  I had "assumed" (and  I
>know  what  words "ass- u-m-e" contain) that I was  dealing  with
>"natural  thorium"  (Th-232),  but much to my  surprise  I  found
>thorium(s)  and  their daughter(s) ("progeny" of course,  is  the
>politically  correct  word now-a-days) from OTHER decay series  -
>e.g.  U-238  and MAYBE some from U-235 although with a  Ni(tl)  I
>wouldn't bet money on it (I won't list all of the isotopes unless
>someone  is REALLY interested).  I tried a "newer" (I had  bought
>within 4 years or so) lantern mantel and found just Th-232 peaks.
>
>     Hey what gives here, do I have a deviant lantern mantel?  Am
>I  having a religious experience?  Has anyone else had a  similar
>experience?  Enquiring minds want to know!
>
>     Thanks,
>
>     Joel Baumbaugh (Baumbaug@nosc.mil)
>     NRaD
>     San Diego, CA
>
>STD  Disclaimer re: the Navy, the Fed.Gov., NRaD, my boss and  my
>co- workers.
>
>
>

   Joel:


   Natural deposits of thorium and natural deposits of rare earth 
elements typically have uranium present also in somewhat elevated 
amounts.

   It seems that your lantern mantel did not have completely purified
thorium.  
                                   
                                                   R. Holloway