# Generating a highly uniform magnetic field inside the magnetically shielded room of the n2EDM experiment

## TL;DR

Researchers designed a coil system to create a highly uniform magnetic field for a physics experiment at the Paul Scherrer Institute.

## Contribution

A novel coil system achieves exceptional magnetic field uniformity, surpassing requirements for a neutron Electric Dipole Moment measurement.

## Key findings

- The system generates a 1 μT vertical magnetic field with a relative RMS deviation of 3×10⁻⁵.
- The uniformity meets the n2EDM experiment's needs, enabling sensitivity better than 1×10⁻²⁷ e·cm.
- The system was tested using a mapping robot inside a magnetically shielded room.

## Abstract

We present a coil system designed to generate a highly uniform magnetic field for the n2EDM experiment at the Paul Scherrer Institute. It consists of a main \documentclass[12pt]{minimal}
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\begin{document}$$B_0$$\end{document}B0 coil and a set of auxiliary coils mounted on a cubic structure with a side length of \documentclass[12pt]{minimal}
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\begin{document}$$273~\hbox {cm}$$\end{document}273cm, inside a large magnetically shielded room (MSR). We have assembled this system and characterized its performances with a mapping robot. The apparatus is able to generate a \documentclass[12pt]{minimal}
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\begin{document}$$1~\upmu \hbox {T}$$\end{document}1μT vertical field with a relative root mean square deviation \documentclass[12pt]{minimal}
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\begin{document}$$\sigma (B_z)/B_z = 3\times 10^{-5}$$\end{document}σ(Bz)/Bz=3×10-5 over the volume of interest, a cylinder of radius \documentclass[12pt]{minimal}
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\begin{document}$$40~\hbox {cm}$$\end{document}40cm and height \documentclass[12pt]{minimal}
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\begin{document}$${30}~\hbox {cm}$$\end{document}30cm. This level of uniformity overcomes the n2EDM requirements, allowing a measurement of the neutron Electric Dipole Moment with a sensitivity better than \documentclass[12pt]{minimal}
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\begin{document}$$1\times 10^{-27}e\,\hbox {cm}$$\end{document}1×10-27ecm.