Mapping of the magnetic field to correct systematic effects in a neutron electric dipole moment experiment

TL;DR

This paper details the mapping of magnetic field non-uniformities in a neutron EDM experiment, using Hg co-magnetometry to evaluate and correct systematic effects, thereby improving measurement accuracy.

Contribution

It introduces a comprehensive magnetic field mapping approach to correct systematic errors in neutron EDM experiments, enhancing measurement precision.

Findings

Mapping campaigns improved magnetic field uniformity understanding

Correction of systematic effects increased measurement accuracy

Multiple campaigns demonstrated consistent mapping results

Abstract

Experiments dedicated to the measurement of the electric dipole moment of the neutron require outstanding control of the magnetic field uniformity. The neutron electric dipole moment (nEDM) experiment at the Paul Scherrer Institute uses a 199Hg co-magnetometer to precisely monitor magnetic field variations. This co-magnetometer, in the presence of field non-uniformity, is responsible for the largest systematic effect of this measurement. To evaluate and correct that effect, offline measurements of the field non-uniformity were performed during mapping campaigns in 2013, 2014 and 2017. We present the results of these campaigns, and the improvement the correction of this effect brings to the neutron electric dipole moment measurement.