Development of cesium magnetometer for Neutron Electric Dipole Moment measurement at LANL Electric Dipole Moment (LANL nEDM)
POSTER
Abstract
High-precision measurements of the neutron electric dipole moment (nEDM) require exquisite control and continuous monitoring of magnetic fields at the sub-picotesla level over extended timescales. The sensitivity of optically pumped magnetometers is fundamentally limited by spin-relaxation processes, making an accurate characterization of longitudinal and transverse relaxation essential. As a part of the effort in LANL nEDM to make a 10-fold improvement of the current limit of nEDM measurement, there is a need to develop external magnetometers with high sensitivity at room temperature for nEDM measurement.
In this work, we are investigating the performance of a cesium vapor-cell magnetometer by systematically measuring both longitudinal (T₁) and transverse (T₂) relaxation with optical rotation using balanced polarimetry in the dark. We are studying the dependence of relaxation on vapor-cell temperature and pump-laser power, with emphasis on operation near room temperature, which is critical for nEDM experiments. Heating alkali vapor cells is known to reduce polarization lifetime and increase longitudinal relaxation. Moreover, in nEDM measurements, elevated cell temperatures generate thermal gradients that produce correlated magnetic-field fluctuations, leading to false EDM signals. These considerations motivate the development of magnetometers with high sensitivity at room temperature to achieve the 10-fold goal.
A distinctive feature of this work is the use of a temperature-stabilized single laser beam for both optical pumping and probing, which is crucial in achieving more compact external sensors in nEDM measurement. We have been able to demonstrate long relaxation times of about 200 ms at room temperature, indicating that cesium vapor-cell magnetometers operated under these conditions are promising candidates for high-precision magnetic-field monitoring in next-generation nEDM experiments.
In this work, we are investigating the performance of a cesium vapor-cell magnetometer by systematically measuring both longitudinal (T₁) and transverse (T₂) relaxation with optical rotation using balanced polarimetry in the dark. We are studying the dependence of relaxation on vapor-cell temperature and pump-laser power, with emphasis on operation near room temperature, which is critical for nEDM experiments. Heating alkali vapor cells is known to reduce polarization lifetime and increase longitudinal relaxation. Moreover, in nEDM measurements, elevated cell temperatures generate thermal gradients that produce correlated magnetic-field fluctuations, leading to false EDM signals. These considerations motivate the development of magnetometers with high sensitivity at room temperature to achieve the 10-fold goal.
A distinctive feature of this work is the use of a temperature-stabilized single laser beam for both optical pumping and probing, which is crucial in achieving more compact external sensors in nEDM measurement. We have been able to demonstrate long relaxation times of about 200 ms at room temperature, indicating that cesium vapor-cell magnetometers operated under these conditions are promising candidates for high-precision magnetic-field monitoring in next-generation nEDM experiments.
*LANL/LDRD
Publication: Planned Papers: Systematic study of Cesium vapor alkali relaxations with temperature and laser power
Presenters
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Segun S Adebisi
- University of Michigan