Construction and Performance of the Magnetically Shielded Room for the Neutron Electric Dipole Moment Experiment at Los Alamos National Laboratory

A non-zero neutron electric dipole moment (nEDM) demonstrates a CP violation, which is needed to explain the Baryon Asymmetry of the Universe (BAU). Room-temperature nEDM searches using Nuclear Magnetic Resonance (NMR) are leading the forefront of such methodology, as they can get running faster than their cryogenic sister experiments and provide a R&D platform for developing techniques to improve sensitivities. The nEDM search at Los Alamos National Laboratory (LANL) plans to achieve an improved nEDM sensitivity of 3×10^-27 e·cm. The experiment requires sophisticated Magnetically Shielded Rooms (MSRs) to shield the experiment apparatus from fluctuations of ambient magnetic fields from DC to high frequency excitations.  To achieve the desired sensitivity, we require an ambient gradient smaller than 0.3 nT·m^-1. In this talk, I will describe why such experiments require low ambient magnetic fields, how the design characteristics of an MSR affect its shielding factor, the construction of the LANL nEDM MSR (to be completed October 2021), and present results of performance measurement.