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UBC Theses and Dissertations

Coils, fields and xenon : towards measuring xenon spin precession in a magnetic field for the UCN collaboration Wienands, Joshua Nikolai


In this thesis I present my work on building a set of magnetic coils for the purpose of performing nuclear magnetic resonance (NMR) on Boltzmann polarized protons in water, and on hyperpolarized ¹²⁹Xe. The coils were designed to be used as a method for testing the degree of polarization achieved in ¹²⁹Xe, and for testing the capability of an in-house developed continuous wave (CW) ultraviolet (UV) laser to drive a 2-photon transition in ¹²⁹Xe. This laser will be used to measure the precession frequency of ¹²⁹Xe in a magnetic field, in order to precisely measure the magnitude of that field. This work is being done for the ultra-cold neutron (UCN) collaboration’s flagship experiment: to measure the neutron electric dipole moment (EDM). Previous neutron EDM experiments have only found an upper limit, and have been limited in precision largely because of systematic errors in the magnetic field strength measurement. These experiments, such as the one performed at Institut Laue-Langevin (ILL), which has given us the current lowest limit, used ¹⁹⁹Hg as a co-magnetometer. The UCN EDM experiment will add ¹²⁹Xe in addition to the ¹⁹⁹Hg, to make a dual co-magnetometer. By using multiple species of atoms in the measurement, systematic effects can be greatly reduced. I have characterized the coils that I built by performing NMR on protons in water. I measured the inhomogeneity in the B₀ field, across the sample container, to be 18.9±0.9 μT. It turns out that the homogeneity of the B₀ field can be improved significantly, and it will likely be necessary to do so in order to perform similar experiments on hyperpolarized ¹²⁹Xe. I also found the T₁ time of water in this setup to be 2.7±0.2 s.

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