Speaker
Description
The TRIUMF nEDM experiment aims to constrain the neutron’s electric dipole moment by an order magnitude over the current sensitivity. The experiment employs a magnetically shielded Ramsey Resonance based EDM apparatus employing ultracold neutrons from a spallation based superfluid helium UCN source, currently under construction at TRIUMF. In our experiment, inhomogeneities (gradients) and instability of the applied magnetic fields are expected to be one of the leading sources of systematic errors in the measurement. The magnetic holding field is typically created by coils that are coupled to the passive magnetic shield surrounding the experiment. The innermost layer of the shield acts as a return yoke. This couples the stability of the holding field to the stability of the magnetic shield material which limits the sensitivity reach of the experiment. An alternative to the shield coupled holding field coil is a self-shielded holding field coil. Here, two coils of different sizes with counter-propagating currents work together to provide the holding field inside the EDM cell while canceling each other at distances greater than both coil shells. One primary concern with employing self-shielded coils is to how precisely one needs to place the individual wires of the two coils. To this end, we have been developing a self-shielded holding field coil using the 3D finite element analysis program COMSOL to investigate how misplacements of the coil locations affect the overall homogeneity over the EDM cell. This presentation will discuss our study into this aspect using a box-shaped self-shielded coil.
