Helium-3 Thermal Properties

  • The geometric phase is direction-dependent, so if a particle changes direction frequently the effect can be averaged away.
  • The Helium-3 mean free path (the distance between direction-changing scattering events) is strongly temperature-dependent (λmfp ∝ T-7). Reducing the temperature a fraction of a degree greatly increases λmfp and therefore increases the geometric phase. As a result, running at low temperature and measuring the false EDM gives an extremely sensitive means to measure and reduce the gradients.
  • By measuring the size of the geometric phase and its temperature dependence we can accurately determine is size at the operating temperature and subtract it. We may even be able to eliminate the effect by operating at a temperature and magnetic field where the frequency shift changes sign. (View image)