Development of a Superconducting Switch to Improve Temporal Stability of Magnetic Coils for nEDM@SNS

Discovery of the neutron electric dipole moment (nEDM) would provide direct evidence of CP-violation and could be used to benchmark beyond the Standard Model physics. However, the nEDM has not yet be found; today, the upper limit is set at 1*10^-26 e*cm. At the Spallation Neutron Source (SNS), the nEDM@SNS collaboration aims to perform a measurement with a sensitivity of 3*10^-28 e*cm. In order to reach the desired precision, the magnetic field of the experiment must be extremely stable over time. Power supplies cannot achieve the required stability; therefore, a superconducting switch will be used to close the superconducting coil that creates the field. In this talk, I present progress on the design, fabrication, and testing of a low current superconducting switch. The initial prototype switch will be used in SOS@PULSTAR - a test system for nEDM@SNS - and may be used for the larger-scale nEDM@SNS experiment. The switch will operate at a current of <500 mA, is made of nonmagnetic materials, and will be joined to the coil using superconducting solder (Ostalloy 203) joints. Initial tests have confirmed the creation of a superconducting joint with a resistance ~3.1*10^-16 Ω, which meets the temporal stability requirements of the experiment.