The Assembly and Testing of the Spin Dressing Magnet for the Neutron Electric Dipole Experiment

Citation

Fox, Jessica Lauren (2025) The Assembly and Testing of the Spin Dressing Magnet for the Neutron Electric Dipole Experiment. Senior thesis (Major), California Institute of Technology. doi:10.7907/rjne-gy68. https://resolver.caltech.edu/CaltechTHESIS:06112025-032822492

Abstract

The discrepancy between the quantity of matter and anitmatter in the universe is something that can likely be attributed to violations in the fundamental symmetries of the universe; however, much like the antimatter itself, there is a discrepancy between the required versus obeserved magnitude of these violations. One theory states that, to account for these violations in symmetry, the neutron must have an electric dipole moment. One such method to find the existence and magnitude of the neutron electric dipole moment (nEDM) is the critical dressing method. Such a method requires the use of two superconducting magnets with perpendicular magnetic fields. This specific method of critical dressing uses superfluid Helium-4, polarized Helium-3, and ultracold polarized neutrons, with critical dressing occurring when the Helium-3 precession rates are equivalent. This method is used to determine the existence of an nEDM, if there is critical dressing with an electric field, there is no nEDM, but if there is a precession rate difference with the electric field, there is an EDM that can thus be measured. Over the past several months, the assembly of the spin dressing magnet used in the critical dressing portion of the nEDM experiment has begun. This has included assembling the boss rings, constructing the magnet frame, placing the story sticks and wire guides, and winding the superconducting wire around the coil skeleton. Data was also taken using this wire. Furthermore, simulations have been run on COMSOL Multiphysics to compare the theoretical predictions with the measurements of the magnetic field and B-field gradients produced by the spin dressing magnet.

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