Magnetic Field System in the nEDM@SNS Experiment*

The neutron electric dipole moment (nEDM) is one of the most sensitive probes of charge-conjugation and parity (CP) violation. The current upper limit for the nEDM is d_n < 1.8×10^-26 e-cm (90% CL). The nEDM experiment at the Spallation Neutron Source (nEDM@SNS) aims to reduce this limit by two orders of magnitude. Targeting a sensitivity of < 3×10^-28 e-cm, it is important to suppress false EDM signals due to the geometric phase effect which arises from nonuniformities in the magnetic field. The required uniform magnetic field, with gradients in the holding field < 3 ppm/cm, will be generated by a modified, saddle shaped cosθ coil enclosed in a nearly-hermetic superconducting lead shield. This talk will present the design, construction and status of the magnetic field system in the nEDM@SNS experiment.