Development on cryogenic valve (V1) for the SNS nEDM experiment

The goal of the nEDM experiment at the Spallation Neutron Source (SNS) is to search for a neutron electric dipole moment (EDM) with a sensitivity below $5 \times 10^{-28}$ e-cm as a signature of Charge-Parity violation, which is $\sim 50$ times better than the current experimental limit. The experiment utilizes polarized $^3$He as a co-magnetometer and as a method to measure the precession frequency of the neutron in-situ. This method improves both the statistical and systematic sensitivity of the experiment, however, does create many technical challenges. One of these challenges is the cryogenic V1 valve operating at 0.4 K, which isolates the ultra cold neutron (UCN) cell from the $^3$He transfer system. The valve has to be UCN friendly, mechanically robust, $^3$He leak tight, friendly to polarized $^3$He, etc. We will report the progress of the R/D effort of the V1 valve.