Magnetic Field Stabilization for Magnetically Shielded Volumes by External Field Coils.
For highly sensitive magnetic measurements, e.g., a measurement of the neutron electric dipole moment (EDM), the magnetic field has to be stable in time on a level below picoTesla. One of several measures we employ to achieve this uses an external field coil system which can stabilize the ambient external field at a predefined value. Here we report on the construction and characterization of such a system in the magnetic test facility at PSI. The system actively stabilizes the field along the axis of the EDM experiment by means of four coils in a Helmholtz-like configuration. Additional coils serve to compensate for transverse ambient field components. Because of the long integration times in the EDM experiment (about 100 s or more) only slow disturbances have to be corrected for. The performance of the system has been measured using static and moving magnetic sources and suppression factors in excess of 200 have been observed.
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Brys
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Czekaj
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Daum
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Fierlinger
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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George
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Henneck
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Hochman
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Kasprzak
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Kohlik
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Kirch
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Kuzniak
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Kuehne
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Pichlmaier
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Siodmok
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Szelc
Paul-Scherrer-Institut, CH-5232 Villigen, Switzerland.
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Tanner
Helmholtz coils; magnetic field stabilization; magnetic noise