Antineutron
Antineutron je antičestica neutrona sa simbolom n.[1][2][3] On se razlikuje od neutrona samo po tome što neka od njegovih svojstava imaju jednaku veličinu ali suprotan znak.[4] On ima istu masu kao i neutron, i nema neto električni naboj, ali ima suprotan barionski broj (+1 za neutron, -1 za antineutron). To je zato što je antineutron sačinjen od antikvarkova, dok su neutroni sastavljeni od kvarkova. Antineutron se sastoji od jednog gornjeg antikvarka i dva donja antikvarka.
 Kvarkna struktura antineutrona. | |
| Klasifikacija | Antibarion |
|---|---|
| Kompozicija | 1 gornji antikvark, 2 donji antiquarks |
| Statistike | Fermionski |
| Interakcije | Jaka, slaba, gravitaciona, elektromagnetna |
| Status | Otkriven |
| Simbol | n |
| Antičestica | Neutron |
| Otkriven | Brus Kork (1956) |
| Masa | 939,565560(81) MeV/c2 |
| Naelektrisanje | 0 |
| Magnetni moment | +1,91 µN |
| Spin | 1⁄2 |
| Izospin | 1⁄2 |
Pošto je antineutron električno neutralan, on se ne može lako posmatrati direktno. Umesto toga, posmatraju se proizvodi njegove anihilacije običnom materijom. Teoretski, slobodni antineutron treba da se raspadne u antiproton,[5] pozitron i neutrino u procesu analognom beta raspadanju slobodnih neutrona. Postoje teorijski predlozi oscilacija neutron-antineutrona, procesa koji podrazumeva kršenje očuvanja barionskog broja.[6][7][8]
Antineutron je otkriven u sudaru protona-antiprotona u Bevatronu[9] (Larens Berkli nacionalnoj laboratoriji) zaslugom Brusa Korka 1956. godine, godinu dana nakon što je antiproton otkriven.[10][11]
Magnetni moment uredi
Magnetni moment antineutrona je suprotan magnetnom momentu neutrona.[12] On je +1,91 µN za antineutron, dok je −1,91 µN za neutron (relativno na pravac spina). Ovde je µN nuklearni magneton.
Vidi još uredi
Reference uredi
- ^ „The Nobel Prize in Physics 1959”.
- ^ „Antimatter Atoms Trapped for First Time—"A Big Deal"”. 19. 11. 2010.
- ^ Weinberg, Steve (1995-06-30). The quantum theory of fields, Volume 1 : Foundations
. стр. 14. ISBN 0-521-55001-7.
- ^ Lancaster, Tom; Blundell, Stephen J.; Blundell, Stephen (април 2014). Quantum Field Theory for the Gifted Amateur (на језику: енглески). OUP Oxford. стр. 61. ISBN 9780199699339.
- ^ Dirac, Paul (1930). „A Theory of Electrons and Protons”. Proceedings of the Royal Society A. 126 (801): 360—365. Bibcode:1930RSPSA.126..360D. doi:10.1098/rspa.1930.0013
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- ^ R. N. Mohapatra (2009). „Neutron-Anti-Neutron Oscillation: Theory and Phenomenology”. Journal of Physics G. 36 (10): 104006. Bibcode:2009JPhG...36j4006M. arXiv:0902.0834 . doi:10.1088/0954-3899/36/10/104006.
- ^ C. Giunti; M. Laveder (19. 8. 2010). „Neutron Oscillations”. Neutrino Unbound. Istituto Nazionale di Fisica Nucleare. Архивирано из оригинала 27. 9. 2011. г. Приступљено 19. 8. 2010.
- ^ Y. A. Kamyshkov (16. 1. 2002). „Neutron → Antineutron Oscillations” (PDF). NNN 2002 Workshop on "Large Detectors for Proton Decay, Supernovae and Atmospheric Neutrinos and Low Energy Neutrinos from High Intensity Beams" at CERN. Приступљено 19. 8. 2010.
- ^ „The History of Antimatter - From 1928 to 1995”. CERN. Архивирано из оригинала 2008-06-01. г. Приступљено 2008-05-24.(The cited page is noted as "3 of 5". The heading on the cited page is "1954: power tools".)
- ^ „The History of Antimatter - From 1928 to 1995”. CERN. Архивирано из оригинала 2008-06-01. г. Приступљено 2008-05-24.(The cited page is noted as "3 of 5". The heading on the cited page is "1954: power tools".)
- ^ Cork, Bruce; Lambertson, Glen R.; Piccioni, Oreste; Wenzel, William A. (15. 11. 1956). „Antineutrons Produced from Antiprotons in Charge-Exchange Collisions”. Physical Review. 104 (4): 1193—1197. Bibcode:1956PhRv..104.1193C. S2CID 123156830. doi:10.1103/PhysRev.104.1193.
- ^ Lorenzon, Wolfgang (6. 4. 2007). „Physics 390: Homework set #7 Solutions” (PDF). Modern Physics, Physics 390, Winter 2007. Приступљено 22. 12. 2009.
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- Schmidt, G.R.; Gerrish, H.P.; Martin, J.J.; Smith, G.A.; Meyer, K.J. „Antimatter Production for Near-term Propulsion Applications” (PDF). Архивирано из оригинала (PDF) 6. 3. 2007. г.
- Lewis, R. A.; Smith, G. A.; Howe, S. D. (1997). „Antiproton portable traps and medical applications” (PDF). Hyperfine Interactions. 109 (1–4): 155. Bibcode:1997HyInt.109..155L. doi:10.1023/A:1012653416870. Архивирано из оригинала (PDF) 22. 8. 2011. г.
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- ALPHA Collaboration (2011). „Confinement of antihydrogen for 1,000 seconds”. Nature Physics. 7 (7): 558—564. Bibcode:2011NatPh...7..558A. arXiv:1104.4982 . doi:10.1038/nphys2025.
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Spoljašnje veze uredi
- LBL Particle Data Group: summary tables
- -author= -
- Elementary particles: includes information about antineutron discovery (archived link)
- "Is Antineutron the Same as Neutron?" explains how the antineutron differs from the regular neutron despite having the same, that is zero, charge.
- Antiparticle (physics) на сајту Енциклопедија Британика