Development of 3He magnetometer for ultra-sensitive measurements of high magnetic fields in Penning traps
Final Report Abstract
Already in its present status precision magnetometry obviously benefits from the PAMP effect, because the experiment can be compacted and miniaturized (thanks to dispensable optical components). A comprehensive study of the field dependence of PAMP efficiency would be very interesting. We may expect that the efficiency will drop significantly when the electron mean free path λ approaches the gyration radius rc. So we expect this drop to occur below 0.1 T. The limit to PAMP efficiency at high magnetic fields will probably be set by full (fine and hyperfine) magnetic decoupling in the excited states. The experimental findings seem very encouraging but obviously call for further work. Systematic investigations are needed to establish the full potential of PAMP. Theoretical work is also highly desirable and would facilitate optimization and exploitation of the method. We have built ultra-sensitive 3He magnetometers to monitor magnetic fields of order Tesla to a relative precision of δB/B < 10^−12. The sensitivity of this magnetometer which was tested inside the homogeneous field of an MRI scanner is not significantly affected if one allows magnetic field fluctuations of order 10^−4 T. Its range of application can be extended to cryogenic temperatures, e.g., inside the cold bore tube of a Penning trap magnet. Almost all other NMR substances are solid at these temperatures in which the dipolar interaction between the nuclear spins leads to a dramatic decrease of T2* (<1 ms). 3He magnetometers with high sphericity can be used for absolute field measurements since the sample cell itself doesn’t affect the applied magnetic field in contrast to water samples. The only limitation we see in the knowledge of the gyromagnetic ratio ∆γ He / γ He ~ 1.3 x 10^−8 . Up to now single 3He to H2O comparison determines μHe only limited by knowledge of the shielded proton magnetic moment. Therefore, absolute measurements of the same B-field using 3He and H2O cannot be considered independent/uncorrelated. There is an initiative from the group of Klaus Blaum (MPIK Heidelberg) to determine the g-Factor of 3He2+ and 3He+ in Penning traps.
Publications
- Ultrasensitive 3He magnetometer for measurements of high magnetic fields, Eur. Phys. J. D 68:330 (2014)
Anna Nikiel, Peter Blümler, Werner Heil, Manfred Hehn, Sergej Karpuk, Andreas Maul, Ernst Otten, Laura M. Schreiber, and Maxim Terekhov
(See online at https://doi.org/10.1140/epjd/e2014-50401-3) - Spherical fused silica cells filled with pure helium for nuclear magnetic resonance-magnetometry, Review of Scientific Instruments 87, 015103 (2016)
Andreas Maul, Peter Blümler, Werner Heil, Anna Nikiel, Ernst Otten,Andreas Petrich, and Thomas Schmidt
(See online at https://doi.org/10.1063/1.4938251) - Nuclear hyperpolarization of 3He by magnetized plasmas, Phys. Rev. A 98, 063405 (2018)
A. Maul, P. Blümler, P.-J. Nacher, E. Otten, G. Tastevin, and W. Heil
(See online at https://doi.org/10.1103/PhysRevA.98.063405)
