The
esoteric world of theoretical physics went into spasms of enthusiasm
last week when Brookhaven National Laboratory announced the identification
of a new elementary particle. It is not the biggest particle known
or the smallest, and it lives only one ten-billionth of a second. But
physicists all over the world were stirred up because it has almost
precisely the mass that was predicted for it by long-range theory. It
was rather as if Columbus, sailing across the Atlantic, had really
found Japan just where he thought it would be. Plethora of Particles. For years physicists have been confused by the
largely accidental discovery of more and more particles. They appear in
the smashed-up debris of collisions between other particles, and they
show up clear and sharp on bubble-chamber pictures and other detection
devices. By the time about 100 such bits of matter had been found,
physicists began to doubt that they were really elementary. Questions
arose. Were some of the particles merely “states” of other
particles, differing in only minor ways? Were they all just
combinations of a few really elementary particles? No one knew for
sure; no general law relating the particles to one another could be
proved true. One of the most promising attempts to devise such a law was made by
Physicists Yuval Ne'eman of Israel and Murray Gell-Mann of Caltech,
with a contribution from Japanese-born Susumu Okubo of the University
of Rochester. Called affectionately the “eightfold way,” from Buddha's list
of eight virtues that lead to the cessation of pain, the theory is
based on eight quantum numbers or fundamental properties that can be
used to describe particles. The reasoning that supports the eightfold
way is advanced quantum mechanics and beyond the understanding of the
mathematically unanointed, but one of the predictions of the
“way” was clear enough: a particle must exist that has a
negative electric charge and a mass— of 1,676 million electron volts.
It should have a life span of one ten-billionth of a second after it is
formed, and then decay into a xi particle and a pi-meson. Omega-Minus Signature. The unknown particle predicted by the eightfold way
was named omega minus, and both CERN Laboratory in Geneva and
Brookhaven National Laboratory on Long Island started elaborate campaigns
to find it. Brookhaven's apparatus was built around the 33-bev
Alternating Gradient Synchrotron, and it used a
line of magnets and electrostatic separators 400 ft. long to isolate
negative K-mesons. Ten of the K-mesons were allowed to enter
Brookhaven's 80-in. liquid-hydrogen bubble chamber every 2 seconds,
and pictures were taken of the results. Two pictures out of 100,000
showed tracks in the LH2 that proved to be the “signatures” of
omega-minus particles. They all curved just right and took off in the
right directions. Careful calculations with a computer gave the mass
of the new-found particles as 1,686 plus or minus 12 mev. This was
almost uncanny agreement with the predictions of the eightfold way.
