Speaker
Description
The proposed cryogenic neutron electric dipole moment experiment at the Spallation Neutron Source (nEDM@SNS) requires that polarized cold neutrons be transported through a highly nonuniform magnetic field while maintaining high polarization. In this talk, we will present recent progress in magnetic field control and polarization transport studies for the nEDM@SNS experiment, along with depolarization studies of high-permeability materials, Metglas, used for magnetic flux return. First, I will focus on the field control system consisting of a mu-metal magnetic shield and additional compensation coils used to guide polarized neutrons through a low magnetic field region. With a guide field of ~3μT, the system achieved field gradients at the ~1μT m^-1 level and demonstrated normalized polarization transmission >90% under optimized operating conditions. Second, I will discuss measurements of neutron depolarization from different Metglas types. We identified a candidate substitute for the currently installed material that provides similar magnetic performance while producing minimal neutron depolarization. The candidate material’s magnetic domains can be saturated in the low field environment inside the magnetic shield, reducing its impact on neutron spin transport.