Spike wrote:
>I encourage the laughter Jeff. {8^D But I dont get it. Are you saying
there
>is carbon 14 in coal? I meant, wood has carbon 14 to start with, then
>over the eons it takes to form coal, yer 14 goes away, half every 6k years.
Right you are spike. My mistake in thinking you meant it was *all* gone, as in none, zero, zippo, nada. The not-much-more-than-infinitesimal bit that's left is what is used for carbon 14 dating.
Robert Bradbury wrote:
> I think that most
>of our internal radiation exposure comes from K40
I think Robert may be right. Potassium comprises 0.4 % of the body. That's 272 gms. (statistical average?) Of which 0.0118 % is K40, with a half life of 1.28 billion years. So in 200 years, 0.00000035 gms of K40 will decay (0.00000087 gms in 500 yrs). The predominant decay mode is beta decay (99.99%), with energies (as best I could determine from the SMI periodic table software I used to get these numbers) for the event of 1.312 Mev for the *beta disintegration*, 1.46 Mev gamma emission, and 1.33 Mev *other radiation*.
Best, Jeff Davis
"Everything's hard till you know how to do it." Ray Charles