Influence of pump beam truncation on transverse relaxation time of 129Xe in a nuclear magnetic resonance gyroscope

Abstract

In order to investigate the influence of pump beam truncation on the transverse relaxation time of 129Xe nuclear spins in a nuclear magnetic resonance gyroscope, we measured the transverse relaxation rate as a function of pump laser power and vapor cell temperature for two ovens with different optical access sizes. The experimental results conform qualitatively to a theoretical model based on magnetic field gradient induced by polarization gradient of Rb atoms. It is found that the non-uniform power distribution in the beam cross-section led to remarkable relaxation, especially for the 129Xe nuclear spins in a large-size vapor cell. To reduce the polarization gradient, the spatial distribution of the pump laser power in the cell should be as homogenous as possible. These results are of significance to the design of a high precision nuclear magnetic resonance gyroscope.