Rapid measurement of longitudinal nuclear spin relaxation time based on the in-situ longitudinal magnetometer in Rb–Xe comagnetometers

The longitudinal relaxation time T₁ of Xe nuclear spins is an important parameter to determine the performance of Rb–Xe comagnetometers. The industry standard delayed pulse method is time-consuming, and requires multiple π pulses and π/2 pulses. In this work, a direct measurement method for obtaining T₁ based on the in-situ longitudinal magnetometer is introduced with the measurement period shortened to 3-5 T₁. The proposed method requires only a single π pulse, reducing the measurement time by approximately more than 90%. By solving the Bloch equation, the working principle of the longitudinal magnetometer and the measurement method is demonstrated. The experiment shows that the longitudinal magnetometer achieves a linear working range greater than 60 nT, and the difference in measurement results of T₁ through different methods at different temperatures and pump beam power is less than 3%. In addition, the longitudinal magnetometer introduced in this method has broad prospects for measuring the basic physical quantities in comagnetometers.