Neutron electric dipole moment measurement with a buffer gas comagnetometer

A neutron EDM measurement with a comagnetometer is discussed. For magnetometry, polarized xenon atoms are injected into a cylindrical cell where a cylindrically symmetric magnetic field and an electric field are applied for the EDM measurement. The geometric phase effect (GPE), which originates from particle motion in a magnetic field gradient, is analyzed in terms of the Dyson series. The motion of the xenon atom is largely suppressed because of a small mean free path. The field gradient is controlled by means of NMR measurements, where the false effect of Earthʼs rotation is removed. As a result, the GPE is reduced below 10−28e cm10−28e cm.

► A method of high precision neutron EDM measurement is described.
► Geometric phase effects are discussed in terms of Dyson series.
► A magnetic field drift is compensated by means of a buffer gas magnetometer.
► Geometric phase effects are greatly suppressed.
► The systematic error is reduced by two orders of magnitude compared with before.