Development of NMOR magnetometer for spin-maser EDM experiment

We have been developing a high sensitivity atomic magnetometer for atomic EDM experiments using a lowfrequency nuclear spin maser. In the developed nuclear spin maser of ¹²⁹Xe, suppression of drift and fluctuation in the magnetic field is one of the important issues. The magnetometer being developed for spin maser EDM experiments utilizes the nonlinear magneto optical rotation (NMOR) effect in Rb atomic vapor. The enhancement of the optical rotation in a small magnetic field relies on the long spin-coherence time of Rb atoms in a vapor cell. The NMOR spectrum was measured by using fabricated Rb cells coated with an anti-relaxation material. The NMOR spectrum dependence on laser frequency, cell coating, and laser beam diameter were investigated. The magnetic sensitivity at present is 0.2 μG/ √ Hz from observed NMOR and noise spectra.