Transport of polarized 3He for the nEDM experiment at the SNS

The neutron electric dipole moment (nEDM) experiment at the ORNL SNS aims to determine the neutron's electric dipole moment to an accuracy of 5.4 x 10\textasciicircum -28 e cm by measuring the Lamor precession of neutrons using the spin dependent reaction n$+$3He $=$\textgreater p$+$3H$+$764KeV. In the experiment polarized 3He is injected into a free surface of 4He, and then brought to the measurement cell and removed once it depolarizes. The proposed transport method for the 3He, the heat flush mechanism, must be tested. In the heat flush mechanism a thermal gradient along a long pipe, generates phonons whose collisions with 3He, drives 3He transport to the cold end of the pipe. Tests of the heat flush mechanism by measuring the change in 3He concentration at the cold end of a long pipe, using a capacitive pressure sensor, are underway at Harvard University.