pion

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Related to Pions: pons, Mesons, Muons

pion

[pī′on]
Etymology: Gk, pi, 16th letter of Greek alphabet, meson, nuclear particle
any of a family of subatomic particles that can be created in nuclear reactions. Pions are unstable but can exist long enough to be formed into beams and used in certain types of medical therapy, such as the treatment of brain tumors. Pions of suitable energy can penetrate the skull and deliver most of their energy to a tumor while sparing overlying normal tissue. See also negative pi meson pion.
References in periodicals archive ?
Une peur qui, apres une parade miracle de Bravo sur Ronaldo, prend la forme d'un quatrieme pion humiliant, tant par la solitude du Pistolero que par la passe decisive de Jordi Alba, positionne en numero neuf.
The pion is made of a u, d quark-antiquark pair and its mass is about 140MeV.
But the observation of high-energy neutrinos by IceCube indicates that these high-energy pions do decay according to the standard ideas of physics, generating neutrinos whose speed approaches that of light but never exceeds it.
Achieving the mind-boggling velocities measured by OPERA would have required pions with energies 20 times greater than their offspring, Cowsik's team calculates.
Previously unknown forms of matter, such as pion crystals, could account for the results, Helfand says.
If H's had formed in the experiment, lambdas wouldn't have disintegrated into detectable pions, because lambda fusions would have happened a hundred million times faster than lambda decays, Rusek explains.
These reactions generate subatomic particles called pions, which can decay into electrons and positrons.
When pions crash into protons at an energy of about 18 gigaelectron-volts (GeV), the gluons holding the quarks together behave as if they were elastic strings stretched between the quarks.
Pions decay into muons and muon neutrinos, and the muons, in turn, transform into positrons, electron neutrinos, and muon antineutrinos.
These pions decay into muons, muon neutrinos, muon antineutrinos, and electron neutrinos, but not electron antineutrinos.
Instead, it focuses on the behavior of protons surrounded by clouds of pions.
Because deflected electrons would typically travel faster than any pions present, flashes of light in a detector in which the gas density has been properly adjusted would reveal the passage of electrons but not pions.