Mesotron

Part of speech: noun

Definitions

1. An early name for a meson, a subatomic particle with a mass between that of an electron and a proton
2. A particle physics term from the 1930s and 1940s for a meson, a short-lived particle of intermediate mass
3. Once used for the meson, an unstable elementary particle whose mass falls between electrons and protons

Etymology: "Mesotron" was proposed in 1938 by American physicists Carl Anderson and Seth Neddermeyer, who wanted a name for a newly discovered class of particles whose mass fell between that of the electron and the proton. They made the case in a letter to the journal Nature, titled "Mesotron (Intermediate Particle) as a Name for the New Particles of Intermediate Mass." The name was built from the Greek prefix "meso-", meaning "middle" or "intermediate," joined to "-tron," a combining element borrowed from "electron," which by then was familiar from the names of other particles. The name did not last. The particles Anderson and Neddermeyer had found were soon recognized as different from what physicists had expected, and the term that eventually took hold for this family was "meson," a shorter form with the same meaning. "Mesotron" survives mainly as a record of the moment when the particles were still being sorted out and named.