Experimental search for 129Xe atomic EDM with nuclear spin maser technique

The development of a nuclear spin oscillator system, namely a spin maser with an external feedback, for use in the search for 129Xe atomic EDM is presented. By introducing a new current source for the B0 field solenoid, drifts in the maser frequency were remarkably suppressed. This in turn clearly brought out the correlation between the maser frequency and the environmental field. Correcting for the effect of the environmental field, the frequency precision of 5 nHz in the measurement time of 45,000 s was attained. Origins of the remaining drifts in the maser frequency are now under investigation.