 The quark structure of the antineutron. | |
| Classification | antibaryon |
|---|---|
| Composition | 1up antiquark, 2down antiquarks |
| Statistics | fermionic |
| Family | hadron |
| Interactions | strong,weak,electromagnetic,gravitational |
| Symbol | n |
| Antiparticle | neutron |
| Discovered | Bruce Cork (1956) |
| Mass | 939.56542194(48) MeV/c2[1] |
| Mean lifetime | 878.4(5) s (free) |
| Electric charge | 0 e |
| Magnetic moment | +1.91 μN |
| Spin | 1/2 ħ |
| Isospin | 1/2 |
| Antimatter |
|---|
 |
Theantineutron is theantiparticle of theneutron with symboln. It differs from the neutron only in that some of its properties haveequal magnitude but opposite sign. It has the samemass as the neutron, and no netelectric charge, but has oppositebaryon number (+1 for neutron, −1 for the antineutron). This is because the antineutron is composed ofantiquarks, while neutrons are composed ofquarks. The antineutron consists of oneup antiquark and twodown antiquarks.
The antineutron was discovered inproton–antiproton collisions at theBevatron (Lawrence Berkeley National Laboratory) by the team ofBruce Cork, Glen Lambertson,Oreste Piccioni, and William Wenzel in 1956,[2] one year after theantiproton was discovered.
Since the antineutron is electrically neutral, it cannot easily be observed directly. Instead, the products of itsannihilation with ordinary matter are observed. In theory, a free antineutron shoulddecay into anantiproton, apositron, and aneutrino in a process analogous to thebeta decay offree neutrons. There are theoretical proposals ofneutron–antineutron oscillations, a process that implies the violation of thebaryon number conservation.[3][4][5] There is a project to search for neutron-antineutron oscillations using ultracold neutrons.[6][7][8][9]
Themagnetic moment of the antineutron is the opposite ofthat of the neutron.[10] It is+1.91 μN for the antineutron but−1.91 μN for the neutron (relative to the direction of thespin). HereμN is thenuclear magneton.
| Elementary |
| ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Composite |
| ||||||||||||||||||||||||
| Quasiparticles | |||||||||||||||||||||||||
| Lists | |||||||||||||||||||||||||
| Related | |||||||||||||||||||||||||
