Design and performance of an absolute 3He/Cs magnetometer

Abstract

Abstract. We report on the design and performance of a highly sensitive combined 3 He/Cs magnetometer for the absolute measurement of magnetic fields. The magnetometer relies on the magnetometric detection of the free spin precession of nuclear spin polarized 3 He gas by optically pumped cesium magnetometers. We plan to deploy this type of combined magnetometer in an experiment searching for a permanent electric dipole moment of ultracold neutrons at the Paul Scherrer Institute (Switzerland). A prototype magnetometer was built at the University of Fribourg (Switzerland) and tested at Physikalisch-Technische Bundesanstalt (Berlin, Germany). We demonstrate that the combined magnetometer allows Cramér-Raolimited field determinations with recording times in the range of 10 ∼ 500 s, measurements above 500 s being limited by the stability of the applied magnetic field. With a 100 s recording time we were able to perform an absolute measurement of a magnetic field of ≈ 1 µT with a standard uncertainty of ∆B ∼ 60 fT, corresponding to ∆B/B <6×10 −8 .

A sensitive and accurate atomic magnetometer based on free spin precession

“…FSP signals have been deployed for specific magnetometry tasks using (nuclear) spin-polarized mercury atoms [15] and 3 He atoms [16,17], or (electronic) spinpolarized alkali atoms [18][19][20]. The good signal to noise ratio and simplicity of its implementation makes the FSP technique based on atomic alignment (i.e., using linearly polarized light) a useful tool for the easy calibration of magnetic coils [21], or for measuring the magnetic field orientation and modulus [20].…”

Optically polarizedHe3

“…As such samples are now realizable, the primary challenges are detection and, for non-magnetic applications, compensation for environmental magnetic noise. Detection strategies to date include inductive pickup (Chupp et al , 1988), SQUID detection (Gemmel et al , 2010; Greenberg, 1998; Savukov et al , 2008), external atomic magnetometers (Cohen-Tannoudji et al , 1969; Koch et al , 2015a, b; Kraft et al , 2014), fluxgate magnetometers (Guigue et al , 2015; Wilms et al , 1997) and, specific to SEOP implementations, using the embedded alkali atoms to detect the 3 He precession (Kornack and Romalis, 2002; Zou et al , 2016). …”

“…The basic principle is to transport 3 He from a MEOP pumping setup inside the magnetic shield where the EDM experiment is located. They detect free-induction-decay of the 3 He with lamp-pumped (Kraft et al , 2014) or multiple laser-pumped (Koch et al , 2015a, b) Cs magnetometers.…”

Dual atomic interferometer with a tunable point of minimum magnetic sensitivity

“…Atoms can be configured as magnetometers that achieve sensitivity slightly better than other available technologies [1]. These sensors have been used to achieve magnetic noise free regions [2][3][4][5], to study biomagnetism [6,7], to generate squeezing in spin systems [8][9][10] or to look for physics beyond the Standard Model [11,12].…”