Calculation of magnetic field noise from high-permeability magnetic shields and conducting objects with simple geometry

By Seung-Kyun Lee, M. Romalis. 2007

160 citations recorded by the source corpus.

High-permeability magnetic shields generate magnetic field noise that can limit the sensitivity of modern precision measurements. We show that calculations based on the fluctuation-dissipation theorem allow quantitative evaluation of magnetic field noise, either from current or magnetization fluctuations, inside enclosures made of high-permeability materials. Explicit analytical formulas for the noise are derived for a few axially symmetric geometries, which are compared with results of numerical finite element analysis. Comparison is made between noises caused by current and magnetization fluctuations inside a high-permeability shield and also between current-fluctuation-induced noises inside magnetic and nonmagnetic conducting shells. A simple model is suggested to predict power-law decay of noise spectra beyond a quasi-static regime. Our results can be used to assess noise from existing shields and to guide design of new shields for precision measurements.

Subfields: Atomic and Molecular Physics, and Optics, Geophysics

View Paper: https://www.semanticscholar.org/paper/18bac84ae24fa301c962a2519302445886b2d023

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In Atomic and Molecular Physics, and Optics

1. P. Fierlinger
2. J. Singh
3. Timothy E. Chupp
4. M. Ramsey-Musolf

Citations in the corpus

• Electric dipole moments of atoms, molecules, nuclei, and particles (2017, background): “Also, any conductor close to the experiment produces Johnson current noise, which in turn causes magnetic-field noise (Lee and Romalis, 2008).”