Optimized Condition for Buffer Gas in Optical-Pumped Magnetometer Operated at Room Temperature

Abstract

The optimal buffer-gas condition for achieving low noise in room temperature optical-pumped magnetometers (OPMs) was determined. To find this optimal condition, various buffer gases (helium, neon, argon, and nitrogen) filled in cesium cells at pressures of 1, 10, 50, 300, or 1000 Torr were tested. Magnetic-resonance signal was detected by sweeping rf frequency, and maximum intensity ( I max ) and line width (Δ f ) in the magnetic-resonance spectra were measured. As an appropriate figure of merit for OPMs, the “α value” (i.e., I max /Δ f ) is defined. It was found that the α value of the cells decreased as gas pressure increased. The α value obtained from the cell filled with neon gas (at 1 Torr) at optimal rf field of 50 nT was the largest. It was inferred from these results that the spin-destruction collision between cesium atoms and the buffer gas has a significant influence on the α value.