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Achieving ultra-low and -uniform residual magnetic fields in a very large magnetically shielded room for fundamental physics experiments
n2EDM is the current state of the art experiment carrying out a high-precision search for an electric dipole moment of the neutron at the ultra-cold neutron source of PSI. In order to reach it’s incredible precision of 10-27 e cm, a stable and uniform magnetic environment is critical. Thus, shielding the experiment from external magnetic flux and preparing a pristine magnetic environment is crucial. To achieve this, n2EDM uses both passive and active magnetic shielding components. External, or residual, magnetic field contributions must be near-zero, and can be achieved via “degaussing” the experiment’s passive magnetic shielding. Degaussing reduces, ideally “erases”, the residual magnetization of a material. In this work, we greatly improved the degaussing procedure of n2EDM, reducing the residual magnetic field by a factor of two, improving its uniformity, and all while taking less time and dissipating less heat.
CNRS movie on n2EDM
Our French collaborators and CNRS produced an excellent short movie about our common n2EDM experiment. The apparatus is currently being set up in
UCN Area South. The collaboration is on track for commissioning of the apparatus with neutrons towards the end of 2022.
Magnetically shielded from the rest of the world
The shielding room in which the n2EDM experiment is expected to clarify whether the neutron has a measurable electric dipole moment or not.
(Photo: Paul Scherrer Institute/Markus Fischer)