Magnetic Field Persistence for nEDM Experiments

Neutron electric dipole moment experiments require extremely stable magnetic fields for sensitivity to electric precession frequencies at least 10 orders of magnitude smaller than the Larmor precession. In cryogenic experiments, a superconductor is used to shield the precession chamber from external magnetic fields. However, during cooldown, some areas go superconducting before others, which can trap inhomogeneous magnetic fields in the shield. A superconducting mesh provides the same persistence as a solid superconducting shield while not displacing the magnetic flux, creating more predictable fields. This allows the precession field to be generated outside the cryostat. We fabricated a rectangular prism out of a lead mesh with a temperature probe and magnetic field probe inside. We will use multiple methods to test the persistence of the magnetic field inside the superconducting mesh both during and after the superconducting transition.