Re[2]: Th-232 air sample analysis -Reply

[Michael S Ford <MFORD@pantex.com>]

Rodney,  I'm feeling a bit slow this AM (OK, *every* AM)....

Since you're dealing with Th-232, wouldn't you be continuously
feeding the thoron daughters?  That is, if you've got Th-232 on the
filter, the thoron progeny won't dissipate.  Right?  (I told you I'm
feeling slow).

What are your thoughts on this?  Do you use the 7-day decay to rule
out natural background only?  And if you see thoron progeny after
7-days, you attribute it to the Th-232 chain?

Continuous air monitoring for Th-232 is generally accomplished by
lowering the ROI window to exclude the radon/thoron tails.  Since
there is about a 2 to 4 MeV difference in alpha energies btw Th-232
and radon/thoron progeny, this can be accomplished fairly easily. 
This technique can also be readily transferred to a lab analysis.

My own personal/non-corporate thoughts,
v/r
Michael
mford@pantex.com
TX Radiation Advisory Board

>>> Rodney Bauman wrote on Tue 21 Sep 99  7:19 >>>

I would imagine that this method also requires a sample decay
period of many (7+) days prior to counting, in order to allow for
decay of the short-lived thoron daughter products....
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