Re: pinhole Mesons

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From: Paul Doherty (pauld@exploratorium.edu)
Date: Sat Nov 20 1999 - 15:31:02 PST 

Message-Id: <l0311070fb45cdebc6c86@[192.174.2.173]>
Date: Sat, 20 Nov 1999 15:31:02 -0800
From: Paul Doherty <pauld@exploratorium.edu>
Subject: Re: pinhole Mesons

Resonding to Sarah's Meson question

The following site describes the Caltech physics laboratory where students
measure the life of a meson.

The mesons are created by cosmic rays are captured in a plastic block where
they come to rest with a flash of light to say that they have arrived and
are at rest. The students measure the time until the second flash of light
that accompanies the muon's decay. So the muon's lifetime is measured for
muons at rest. (For a particle with a half life it doesn't matter how long
they have lived before you start measuring, no matter how long they have
lived already, if they are alive when you start timing you will measure the
correct half life.

Moving mesons have a much longer half-life due to relativistic time dilation.

http://tweedledee.wonderland.caltech.edu/~derose/labs/exp15.html

Paul D

Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld

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