Re:: Thorium in lantern mantles

[baumbaug@nosc.mil (Joel T. Baumbaugh)]

     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.