unstable particle


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Related to unstable particle: muon, electron

unstable particle

[¦ən′stā·bəl ′pärd·ə·kəl]
(particle physics)
Any elementary particle that spontaneously decays into other particles.
An elementary particle that can decay through the strong interactions, as opposed to a semistable particle; it has a lifetime on the order of 10-23 second.
References in periodicals archive ?
The physics of neutrino mass and its cosmological manifestations, the physical fundamentals of the existence and possibilities of astronomic search for the mirror and shadow matter, unstable massive neutrinos, invisible axions, and the domains of antimatter in the baryon-asymmetric universe, primary black holes, various stable and unstable particles of the hidden mass are just some of the problems of elements of cosmomicrophysical analysis which should be studied when investigating the universe and physical laws determining its origin, structure and evolution.
Mesons: the decay of these unstable particles that result from high-speed proton collisions.
The researchers fired a beam of antiprotons into a liquid-helium target, then used a sodium iodide detector to measure the energy--in the form of unstable particles known as pions--coming out of the target.