A large 'Active Magnetic Shield' for a high-precision experiment: nEDM collaboration.

Area of Science:

• Experimental Physics
• Particle Physics
• Applied Electromagnetism

Background:

• High-sensitivity searches for the neutron electric dipole moment (n2EDM) require exceptional magnetic field stability.
• Existing magnetically shielded rooms (MSRs) offer passive shielding but struggle with dynamic field fluctuations.
• The n2EDM experiment at the Paul Scherrer Institute necessitates advanced magnetic field control.

Purpose of the Study:

• To design and implement a novel Active Magnetic Shield (AMS) for the n2EDM experiment.
• To achieve a stable and uniform magnetic field environment within the MSR.
• To compensate for static and variable magnetic fields, including homogeneous components and first-order gradients.

Main Methods:

• Developed an Active Magnetic Shield (AMS) comprising eight feedback-controlled compensation coils.
• Integrated the AMS on an irregular grid within a compact volume (<1000 m³) around the MSR.
• The system compensates static and dynamic magnetic fields up to specific limits, suppressing them to the sub-Hertz frequency range.

Main Results:

• The AMS successfully provides a stable and uniform magnetic field environment around the MSR.
• The system demonstrates the capability to compensate static and variable magnetic fields up to specified limits.
• Magnetic fields are suppressed to a few nT in the sub-Hertz frequency range.

Conclusions:

• The novel Active Magnetic Shield design fulfills the stringent requirements of the n2EDM experiment.
• The AMS offers a compact and effective solution for creating magnetically silent environments.
• This technology is applicable to other experiments requiring high magnetic field stability under spatial constraints.