Antineutron
The antineutron or antineutron is the antiparticle of the neutron. It was discovered by Bruce Cork in 1956, a year after the discovery of the antiproton. The antineutron has the same mass value as a neutron, and no electric charge. However it differs from a neutron by being composed of antiquarks. Particularly the antineutron is composed of two antiquarks down and one antiquark up. The magnetic moment of an antineutron is contrary to that of a neutron. It is +1.91 μN for the antineutron number -1.91 μN. Here the μN is the elemental unit of the magnetic moment, determined nuclear magnéton. Knowing that the antineutron is electrically neutral, it can not be easily observed directly. Instead the annihilation of their products with ordinary matter are observed. There are theoretical propositions that indicate that neutron-antineutron oscillations exist, a process that would only happen if there is an undiscovered physical process that violates the conservation of baryon number.