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An optically pumped resonance magnetometer has been constructed which utilizes 4He gas as the resonant element in the self-oscillator mode of operation. This instrument is capable of monitoring anomalies and fluctuations in the magnetic field with a sensitivity of 0.1 μG over the range of the earth's field (0.25–0.75 G). Recordings of variations in the geomagnetic field are compared with recordings made simultaneously with a servo helium magnetometer. The characteristics and advantages of the new system are discussed.
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Slocum et al. (1971) studied this question.
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