Frequency characteristics of a nuclear spin maser for the search for the electric dipole moment of ¹²⁹Xe atom

Frequency characteristics of a ¹²⁹Xe nuclear spin maser was studied, which is under development at Tokyo Institute of Technology for the search for a permanent electric dipole moment in diamagnetic ¹²⁹Xe atom. Drifts in the solenoid current and cell temperature were found to be the most influential factors on the maser frequency. From correlation coefficient analysis, there seem to exist other origins of frequency fluctuation, such as phase drifts in the maser oscillation. In order to improve the stability of the maser frequency, the intensity of the pumping laser required to fully polarize ¹²⁹Xe nuclei was evaluated. Construction of a polarization assessment system for ¹²⁹Xe gas cells and development of a new scheme of current stabilization are also remarked.