Neutron
The neutron is an electrically neutral subatomic particle that, together with protons, forms atomic nuclei. It has a rest mass of 1.00866491595 u (≈ 939.565 MeV/c²) and a magnetic moment of –1.913 μN. Discovered by James Chadwick in 1932, free neutrons undergo beta decay with a mean lifetime of about 878 seconds.
