(-13-) From: AstroNet <resource@rahul.net>
Subject: "Top Quark" Identified
Date: 15 March 1995
"TOP QUARK" IDENTIFIED
The zoo of subatomic particles gained a new denizen with the detection of
the "top" quark, the sixth -- and presumably last -- member of the quark
family. The two discovery teams used Fermilab's Tevatron particle
accelerator to create head-on collisions of protons and antiprotons at an
energy of some 2 trillion electron volts. Among the millions of recorded
annihilation events, a few dozen gave rise to the secondary particles
expected from a top quark's decay. Investigators were also able to place
limits on its mass. And what a mass! While the "up" and "down" quarks
found in ordinary matter have masses (in energy units) of 5 million and 8
million electron volts respectively, the top quark tips the scales
between 176 and 199 *billion* electron volts.
As the last of six quark types required to account for baryonic (normal)
matter, the top's discovery fills in one branch of a complex family tree.
This subatomic heavyweight doesn't play much of a role now, but long ago,
in the first microseconds after the Big Bang, the universe consisted of a
quark plasma. So constraining the top quark's mass may provide further
clues to the cosmos's early character.
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- T o d d E. V a n H o o s e a r -
``'''vanhoose@lalaland.cl.msu.edu - vanhoose@msu.edu - vanhoose@lalaland.cl.msu.edu
(._.) Michigan State University - East Lansing, MI USA
(_) Computer Laboratory - Department of Communication
`---' <A HREF="http://lalaland.cl.msu.edu/~vanhoose/">My Home Page</A>
"I.R.S.: We've got what it takes to take what you've got!"
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