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Ultrasensitive 3He NMR-magnetometry for measurements of high magnetic fields

Kolloquium der Abteilung 2

Abstract. In the talk a 3He magnetometer is descibed capable to measure high magnetic fields (B > 0.1 T) with a relative accuracy of better than 10-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2* being of order minutes which is achieved for spherical sample cells in the regime of “motional narrowing” where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in situ using a new, non-standard variant of the metastability exchange optical pumping.