| A new search for the electric dipole moment of the neutron has been proposed that will be housed at the Spallation Neutron Source at Oak Ridge National Laboratory [1]. The nEDM experiment is part of a class of new experiments aimed at searching for physics beyond the Standard Model, particularly in the CP and T violating sectors. Several proposed extensions to the Standard Model predict values for the electric dipole moment of the neutron. Thus, the discovery of a nonzero electric dipole moment for the neutron (nEDM) would have a fundamental impact upon the current understanding of the weak and strong nuclear interactions.;The nEDM measurement takes place in liquid helium, doped with trace amounts of polarized 3He that functions as both a detector of neutron spin alignment and as a comagnetometer. When a neutron captures on 3He, the decay products ionize the surrounding 4He atoms, resulting in the production of excited singlet and triplet helium states along the ion path. When these excited states relax, light is produced in the extreme ultraviolet, which is then detected. The character of this scintillation light depends on the mass and energy of the ionizing particle. We are therefore characterizing this scintillation light for use as a method of discriminating neutron capture from backgrounds.;After the 3He depolarizes, it is necessary to remove it before adding more polarized 3He. It has been proposed that the depolarized atoms be removed using differential evaporation. We have developed a test evaporative purification apparatus that can facilitate this removal, therby lowering the concentration of 3He in 4He from approximately 10-10 to 10-12. The operating temperature for the experiment, 350 mK to 500 mK, places a constraint upon the effectiveness of this technique. It is therefore necessary to design and optimize an apparatus capable of performing the above mentioned purfication in a time much less than the nEDM measurement time of approximately 22 minutes. Additional experimental concerns involve minimizing the introduction of heat to the system, effectively removing the evaporated gas from the testing area, and testing of evaporator performance. |
