A system to provide sub-milliKelvin temperature control at T~300K for extreme precision optical radial velocimetry

We present preliminary results for the environmental control system from NEID, our instrument concept for NASA's Extreme Precision Doppler Spectrograph, which is now in development. Exquisite temperature control is a requirement for Doppler spectrographs, as small temperature shifts induce systematic Doppler shifts far exceeding the instrumental specifications. Our system is adapted from that of the Habitable Zone Planet Finder instrument, which operates at a temperature of 180K.We discuss system modifications for operation at T ~ 300K, and show data demonstrating sub-mK stability over two weeks from a full-scale system test.