Simulation of time dependent magnetic field variations in the SNS nEDM experiment

The Spallation Neutron Source (SNS) neutron electric dipole moment experiment (nEDM) requires precise control of the magnetic field. Time-dependent variations in the magnetic field will be monitored with the polarized $^3$He co-magnetometer via detection of the precessing $^3$He magnetization in SQUID pickup loops. The resulting SQUID signal will then be used to correct for these time dependent magnetic field variations that appear in measurements of the neutron and $^3$He precession frequency difference. We have carried out simulations of the response of the SQUID $^3$He co-magnetometer to time-dependent variations in the magnetic field and have explored various schemes for corrections to the measured neutron precession frequency due to these time-dependent magnetic field variations. Preliminary results showing the sensitivity of the extracted neutron precession frequency to magnetic field variations will be discussed.