The quark structure of the antineutron.
|Composition||1 up antiquark, 2 down antiquarks|
|Interactions||Strong, Weak, Gravity, Electromagnetic|
|Discovered||Bruce Cork (1956)|
The antineutron is the antiparticle of the neutron with symbol n. It differs from the neutron only in that some of its properties have equal magnitude but opposite sign. It has the same mass as the neutron, and no net electric charge, but has opposite baryon number (+1 for neutron, −1 for the antineutron). This is because the antineutron is composed of antiquarks, while neutrons are composed of quarks. The antineutron consists of one up antiquark and two down antiquarks.
Since the antineutron is electrically neutral, it cannot easily be observed directly. Instead, the products of its annihilation with ordinary matter are observed. In theory, a free antineutron should decay into an antiproton, a positron and a neutrino in a process analogous to the beta decay of free neutrons. There are theoretical proposals that neutron–antineutron oscillations exist, a process which would occur only if there is an undiscovered physical process that violates baryon number conservation.
The magnetic moment of the antineutron is the opposite of that of the neutron. It is µN for the antineutron but +1.91 for the neutron (relative to the direction of the −1.91 µNspin). Here µN is the nuclear magneton.
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- C. Giunti; M. Laveder (19 August 2010). "Neutron Oscillations". Neutrino Unbound. Istituto Nazionale di Fisica Nucleare. Retrieved 19 August 2010.
- Y. A. Kamyshkov (16 January 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. Retrieved 19 August 2010.
- Lorenzon, Wolfgang (6 April 2007). "Physics 390: Homework set #7 Solutions" (PDF). Modern Physics, Physics 390, Winter 2007. Retrieved 22 December 2009.
- LBL Particle Data Group: summary tables
- suppression of neutron-antineutron oscillation
- 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.