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Re: Radioactive decay



-----Original Message-----
From: Ludwik Kowalski [mailto:kowalskiL@MAIL.MONTCLAIR.EDU]
Sent: Sunday, August 25, 2002 4:31 PM

In a tangential remark JohnD wrote (yesterday):

If the decay rate of 16.66% per round is too fast, you
can lower it by various means. You can lower by a
factor of 4 by saying that they only decay if they land
black-spot-up _and_ pointing toward the north side
of the room.

This prompted me to go back and to discover a detail
which becomes important when results of simulations
(for large numbers of atoms) are compared with the
experimentally measured, or theoretically predicted
half-life. Here is a challenge for students asked to
create a simulation program, as that shown at the
end of this message (same as yesterday).

[snip]

Then I used another program to obtain the best exponential fit.
The resulting half-live turned out to be 3.73 units. Ask your
students why this result is not the same as the theoretically
expected T=ln(2)/lambda=4.11 units.

As pointed out in
<http://lists.nau.edu/cgi-bin/wa?A2=ind9905&L=phys-l&P=R12037>, I believe
the difference can be modeled as lambda/2 (although higher order terms will
be needed in this case since lambda is so large).

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; 570-422-3428; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301