Magnetic Moment of the Neutron

Abstract The neutron is a Dirac particle and according to the Dirac equation it must have a zero magnetic moment. However, at the beginning of the 1930s, as soon as the magnetic moments of the proton and deuteron had been determined, Esterman and Stern[168] showed that the obtained results led to a hypothesis of the neutron having a negative magnetic moment of about 2µN, where µN = eħ/2mpc is the nuclear magneton and mP is the proton mass. Tamm and Altschuler[169] were able to make an analogous suggestion on analysing the nuclear magnetic moments data. In 1937 Frisch et al.[170] made one of the first attempts to determine the magnetic moment of the neutron µn by observing the reorientation of the moments in a beam of polarized neutrons using an alternating magnetic field in resonance with the Larmor frequency of precession of the neutrons in a superimposed uniform magnetic field. The result of the experiment was more qualitative than quantitative and confirmed that the neutron magnetic moment is negative and approximately equal to 2µN.