Closed Loop Helium Gas Cooling System for the Nab Experiment

The Nab experiment at the Spallation Neutron Source will use an unpolarized neutron beam to measure the electron-neutrino correlation coefficient, 'a', and the Fierz interference term, 'b', to further our understanding of the weak interaction. The protons and electrons from neutron beta decay will be measured by pixelated silicon detectors. To minimize noise and optimize energy and timing resolution, the detector will be actively cooled to below 200K. Temperature regulation will be achieved by a closed loop helium gas cooling system. This talk will focus on the design, characterization, and performance of this system.