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Any of the three least massive mesons, having a positive, neutral, or negative electric charge. The charged pions have a mass 273 times that of an electron and a mean lifetime of 2.6 × 10-8 second, and the neutral pion has a mass 264 times that of an electron and a mean lifetime of 8.4 × 10-17 second. Also called pi meson.

[Contraction of pi meson.]


(ˈpaɪɒn) or

pi meson

(General Physics) physics a meson having a positive or negative charge and a rest mass 273.13 times that of the electron, or no charge and a rest mass 264.14 times that of the electron
[C20: from Greek letter pi1 + on]


(ˈpaɪ ɒn)

any of the three lightest mesons, having positive, negative, or neutral electric charge and spin of zero.
[1950–55; pi (meson) + -on1]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.pion - a meson involved in holding the nucleus together; produced as the result of high-energy particle collision
meson, mesotron - an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0
References in classic literature ?
John, and was formerly Christian Church ;) further toward you is the hill of Pion, around whose front is clustered all that remains of the ruins of Ephesus that still stand; divided from it by a narrow valley is the long, rocky, rugged mountain of Coressus.
By-and-by they came to a marvelous cave in the Hill of Pion and entered into it and feasted, and presently they hurried on again.
Paul, where we all did use to go to touch the ancient chains that bound him and be cured of our distempers; I see the tomb of the disciple Luke, and afar off is the church wherein repose the ashes of the holy John, where the Christians of Ephesus go twice a year to gather the dust from the tomb, which is able to make bodies whole again that are corrupted by disease, and cleanse the soul from sin; but see how the wharves encroach upon the sea, and what multitudes of ships are anchored in the bay; see, also, how the city hath stretched abroad, far over the valley behind Pion, and even unto the walls of Ayassalook; and lo, all the hills are white with palaces and ribbed with colonnades of marble.
Car l'antre blanche ne le sait que trop bien, la difference de niveau, abyssale, appelle de nouveaux pions blaugrana.
Pions quickly decay into gamma-ray photons, little high-energy particles of light that are unaffected by magnetic fields.
Hence, in order to avoid contradictions with the existence of charged pions and [W.
Neutrinos in this experiment are emitted in the decay of subatomic particles called pions; the pions possess far less energy than the amount required by the neutrinos to exceed light speed.
The neutrinos in the experiment were created by slamming speeding protons into a stationary target, producing a pulse of pions -- unstable particles that were magnetically focused into a long tunnel where they decayed in flight into muons and neutrinos.
The topics include exotic nuclei with open heavy flavor mesons, baryon anti-decuplet in the chiral quark-soliton model, chiral properties of baryons, exotic cluster structures excited by two neutron transfers, coherent pions from neutrino scattering off nuclei, the present status of microscopic theory for complex nucleus-nucleus interactions, and nuclear and particle physics with ultra-intense lasers.
Protons from the 30-GeV Main Ring synchrotron were directed onto a carbon target, where their collisions produced charged particles called pions.
30pm Manchest (Kick-off 7 finals get first-leg t the Prem champion Portugue EFA pions League m) ter United v FC Porto 7.
Tim Mullock, who is the goalkeeper for the British Univer-sities men's football team, will be visiting as an ambassador of the Sporting Cham- pions Scheme.