Thesis Committee: Haiyan Gao, Glenn Edwards, Kate Scholberg , and Seog Oh (exofficio non-voting member)
In this experiment, we aim to measure the neutron electric dipole moment with unprecedented sensitivity. Polarized Ultra Cold Neutrons are submerged in a superfuid 4He and polarized 3He mixture at 300 to 500 mK. A uniform magnetic field and electric field are applied parallel to the polarizations of both the neutrons and the 3He. The precession frequency of the neutrons is measured relative to that of the 3He nuclei, which is determined through SQUID, by way of the scintillation light signal produced by the 3He + n -> p + t + 734 keV spin-dependent reaction. The electric field is reversed and the neutron precession frequency is measured again. The difference between the two precession frequency measurements is proportional to the neutron electric dipole moment. The 3He polarization plays a crucial role in the sensitivity of the experiment, as it determines the strength of the scintillation signal and the strength of the SQUID signal. 3He is also used as an in situ co-magnetometer in the analysis of systematic errors. The 3He must change polarization direction by coupling to a magnetic field as it is being injected in the 4He superfluid. In the reference frame of the dipoles, the dipoles experience a time-varying magnetic field which induces polarization loss. After the injection the polarization is measured using NMR. This paper concerns the design of magnetic fields to minimize the polarization loss of 3He during its transport into the 4He superfluid and to minimize the effect of nuclear relaxation during the polarization measurement.
Here is the thesis in PDF: Mestler_thesis.pdf