New accelerators with higher energies smashed beams of particles into fixed targets to produce short-lived particles with high masses. One of these particles, the upsilon, had properties that implied that it could not be made of the known four quarks: up, down, strange and charm. Physicists concluded that the upsilon was made of a new quark, the bottom quark, and its antiquark.
Leon Lederman, the second director of Fermilab, headed this 1977 experiment. Today there are accelerators dedicated to the production of upsilons and studies of the bottom quark.
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