| 释义 |
▪ I. ‖ meson1 Anat., etc.|ˈmɛsɒn|
[mod.L., a. Gr. µέσον, neut. of µέσος middle.]
The median plane, which divides a body into two symmetrical halves.
1883Wilder & Gage Anat. Techn. 33 The Meson..is a plane passing lengthwise of the body and dividing the whole into approximately equal and similar right and left halves. 1889Buck's Handbk. Med. Sci. VIII. 536/1 The meson, mesal, or medial plane.
▪ II. ‖ meson2|mɛˈsɒn|
[a. Sp. mesón an inn.]
A type of inn in Mexico (see quot. 1861).
1824J. R. Poinsett Notes on Mexico iv. 32 We entered the town..and drove through it to the meson. 1847G. F. Ruxton Adventures Mexico & Rocky Mts. viii. 52 The meson was better than usual, being the stopping place of the diligencia to Fresnillo. 1861E. B. Tylor Anahuac 209 The meson of Mexico is a lineal descendant of the Eastern Caravanserai... It consists of two courtyards, one surrounded by stabling and the other by miserable rooms for the travellers, who must cook their food themselves, or go elsewhere for it. 1910A. Santleben Texas Pioneer 164 Meson means an inn or hostelry. 1955Amer. Speech XXX. 258 Meson, an inn.
▪ III. meson3 Nuclear Physics.|ˈmiːzɒn, ˈmɛzɒn|
[Alteration of the earlier name mesotron: see -on1.]
a. Any of a group of unstable subatomic particles (first found in cosmic rays) that are intermediate in mass between an electron and a proton; the name is now commonly restricted to particles that are strongly interacting and have zero or integral spin (cf. muon), certain of which occur in atomic nuclei as transmitters of the binding force between the nucleons.
1939H. J. Bhabha in Nature 18 Feb. 276/2 The name ‘mesotron’ has been suggested by Anderson and Neddermeyer..for the new particle found in cosmic radiation with a mass intermediate between that of the electron and proton. It is felt that the ‘tr’ in this word is redundant, since it does not belong to the Greek root ‘meso’ for middle; the ‘tr’ in neutron and electron belong, of course, to the roots ‘neutr’ and ‘electra’... It would therefore be more logical and also shorter to call the new particle a meson instead of a mesotron. 1942Pollard & Davidson Appl. Nucl. Physics ii. 13 The positive and negative mesotrons or mesons should be mentioned here. 1947Sci. News IV. 125 Mesons are the most penetrating component of cosmic rays. 1948Times 10 Mar. 4/7 Other scientists spoke of mesons as the ‘cosmic cement’ which is believed to hold together the nucleus of the atom. 1963S. Tolansky Introd. Atomic Physics (ed. 5) xxiii. 391 They [sc. muons] were once called mu-mesons but it was recognised that they were not in fact mesons since they had different spins. They are fermions, not bosons, and now the name meson is reserved for bosons only. 1971Sci. Amer. Oct. 42/3 Such high-energy cosmic ray collisions produce a shower of secondary particles, principally kaons (K mesons) and pions (pi mesons), which in turn decay spontaneously into muons. Ibid., The detector, a 2,000-ton array of concrete water tanks, light-collecting tubes and gas-filled cylinders, was designed to record the arrival of muons, or mu mesons.
b. Special Comb.: meson factory colloq., an establishment having a high-energy accelerator for producing an intense beam of mesons and the equipment for making experimental use of such a beam.
1966Physics Today Dec. 21/1 Meson factories, which will produce beams of nucleons and mesons thousands of times more intense than those presently available, can be expected to take us to our next level of understanding of nuclear structure... By meson factory I mean a complete nuclear-physics installation based on an accelerator of 500–1000 MeV, which is capable of providing at least 100 microamperes of high quality external beam. All ancillary facilities for performing high precision experiments with the primary and secondary beams are included: targeting, beam transport, data-handling equipment and beam dumps for the residual beams. 1972Physics Bull. Mar. 148/3 With the completion of high intensity proton accelerators, meson factories, around the world.., it will soon be possible to produce muonic atoms and molecules copiously.
▪ IV. meson
obs. form of mason, mizen. |