Children's, Intermediate and Advanced Online English Dictionary & Thesaurus

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alpha particle a positively charged particle given off as radiation from some fission or decay processes, consisting of two protons and two neutrons.
beta particle a high-speed positron or electron ejected from a nucleus in radioactive decay or fission.
elementary particle one of various subatomic particles, such as electrons, neutrinos, or quarks, from which all matter is made.
fundamental particle an elementary particle.
high-energy particle an atom or part of an atom having energy greater than one hundred thousand electron volts.
particle beam a stream of atomic or subatomic particles projected at extremely high speed and used in research, as into nuclear reactions, or in military weaponry.
particle board any of several boardlike building materials made by compressing wood chips, flakes, or sawdust with a bonding resin.
psi particle an unstable meson that is thought to be composed of a quark and its antiparticle.
tau particle a positively or negatively charged lepton whose mass is roughly 3,500 times greater than that of an electron, and that decays fairly quickly.