Re: Thorium in lantern mantles

[rick_strickert@pc.radian.com]

On Monday, 12 Jun 1995, Bruce Pickett asked, in part:

> What is considered to be an "average" activity for thorium mantles and
> how much variability is there?

Recently (1) Keith Ruddick at the University of Minneapolis measured the
Th-232 content in a Silk-Lite 21A lantern mantle, manufactured by Coleman
Co., Wichita, KS.  He reported 19 mg of Th-232, about 5% of the mass of a
burnt mantle.

19 mg of Th-232 is equivalent to a thorium activity of about 4.2 nCi
(150 Bq), including the equilibrium activity of Th-228.

Rick Strickert

1. Keith Ruddick, "Determination of the half-life of 212Po", American
Journal of Physics, 63(7), July, 1995, pp.658-660.


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