The Bevatron was a proton synchrotron at Berkeley. Its circulating beams supplied high-energy protons to fixed targets, producing secondary particles that could be selected and measured downstream. It played a central role in the 1955 discovery of the antiproton. [ref]
https://newscenter.lbl.gov/2005/10/27/the-golden-anniversary-of-the-antiproton/. Berkeley Lab, The Golden Anniversary of the Antiproton: Bevatron proton beam and secondary-particle experiment
A fixed target makes the production threshold more demanding than simply supplying the new particle's rest energy: conservation of momentum requires outgoing motion, and conserved quantum numbers require accompanying particles. This is why accelerator beam energy, collision center-of-mass energy and produced-particle kinetic energy are different quantities.
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The Bevatron was a particle accelerator located at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. It was operational from 1954 until 1993 and was notable for being one of the first large-scale proton synchrotrons, designed primarily for high-energy physics research. The Bevatron was capable of accelerating protons to energies up to 6.