[Phys-L] Re: cosmic rays bombarding rocks

[John Mallinckrodt <ajm@CSUPOMONA.EDU>]

Our "daughter" Claire (too long a story on the quotes for today) is
doing exactly this research at the University of Washington.

<http://depts.washington.edu/cosmolab/people.html>

I've forwarded the post to her and will share any response she might
care to send along.

> I read in the NY Times a week or so ago about dating method to determine
> approximately the time when glaciers retreated and rocks were uncovered.  The
> method involved, I believe, a beryllium isotope, and had a possible precision
> of plus or minus 500 years.
>
> I have not been able to find that article again, but some web searching
> turned up some pages on 'cosmogenesis'. This involves cosmic rays, mostly
> protons and mu mesons, bombarding silicas in rocks and producing Be-10 and
> also Al-26.  The beryllium-10 half-life is about 2.7 million years, so it
> seems like a suitable vehicle for dating on the order of 10,000 - 20,000
> years.
>
> Does anyone have an inkling of how cosmic ray particles could create
> beryllium 10 from oxygen and silicon?

--
John "Slo" Mallinckrodt

Professor of Physics, Cal Poly Pomona
<http://www.csupomona.edu/~ajm>

and

Lead Guitarist, Out-Laws of Physics
<http://www.csupomona.edu/~hsleff/OoPs.html>
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