Magnetic Anomaly Detection by Remote Means
Technical Report,01 Jan 2013,31 Dec 2015
PRINCETON UNIV NJ PRINCETON United States
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Research on the possibility of detecting magnetic anomalies remotely using laser excitation of a naturally occurring atomic or molecular species in air has focused on the use of Xe 129. Although Xe 129 is only present in the atmosphere at molar fractions of tens of parts per billion, it is the best candidate for magnetic detection since it has a nuclear spin of 12, and there is no electron spin to depolarize the nuclear spin. Molecules rapidly lose spin orienation through collisions however Xe129, an inert atomic species, can remain spin polarized for up to seconds in air. This permits the measurement of the surrounding magentic field through the measurement of the spin nutation rate around the external field. The research hasdemonstrated that 10 part per million concentrations of Xe can be detected using 2 plus 1 Radar REMPI, limited by background signals from oxygen. Higher detection sensitivity is anticipated through preparation of metastable Xe followed by 1 plus 1 Radar REMPI. Spin polarization is to be achieved through multiphoton interactions with circular polarized laser light. Proper wavelengths for this multiphoton process have been generated through two photon pumped lasing in atmospheric pressure xenon, and excitation of selected Xe electronic states has been achieved.
- Magnetic and Electric Field Detection and Detectors
- Atmospheric Physics