Simulating the Neutron Electric Dipole Moment experiment at the Los Alamos National Laboratory using COMSOL MultiPhysics

The neutron electric dipole moment (nEDM) has not yet been found, but it has an upper limit of 3.0*10-26 ecm. If a neutron was blown up to the size of the earth, this upper limit is equivalent to a charge separation of less than 1 mm. The nEDM experiment at the Los Alamos National Laboratory (LANL) aims to improve this upper limit by a factor of ten. EDM in fundamental particles violates time reversal symmetry, as the particle’s magnetic dipole moment changes direction while the EDM is unchanged. EDM, if observed at the proposed sensitivity, would  provide the symmetry-violating physics needed to explain the observed matter-antimatter asymmetry. I use a finite-element analysis tool, COMSOL MultiPhysics, to simulate the magnetic fields inside the experiment. Such tool is required to design the apparatus to reduce the earth field by a million fold and to create a uniform magnetic field. A highly uniform field is required to improve the measurement of the frequency shift induced by an applied electric field. The non-linear hysteresis of the mu-metal material is implemented to study how to properly demagnetize the magnetic shield. I also participate in measuring the flux of ultracold neutrons at LANL in preparation for the nEDM measurements. I will present the details of my work.