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Vanbergen, Sean

University of British Columbia

The TRIUMF UltraCold Advanced Neutron (TUCAN) collaboration is developing a new measurement of the neutron electric dipole moment (nEDM) with the goal of improving the current best limit of dn ≤ 1.8 × 10-²⁶ ecm (90% C.L.) to the level of dn ≲ 2 × 10-²⁷ ecm (90% C.L.). A non-zero nEDM requires the violation of charge-parity (CP) symmetry, and so the measurement of the nEDM can shed light on unanswered questions of fundamental physics, such as baryon asymmetry, the strong CP problem, and extensions of the Standard Model.The first part of this dissertation relates to the development of a new source of ultracold neutrons (UCNs). This source is based on the conversion of cold neutrons produced by a dedicated spallation source to UCNs by downscattering in superfluid ⁴He. The new source will enable the desired statistical reach of the experiment. Prior to the construction of the new source, a prototype source was operated at TRIUMF from 2017 to 2019, and was used to perform experiments on UCN production, storage, and transport to assist in the design of the new source. This dissertation describes the results of a subset of those experiments, relating to the production and lifetime of UCNs in superfluid 4He. The second part of this dissertation relates to the design of the TUCAN EDM spectrometer, which implements Ramsey’s method of separated oscillating magnetic fields to search for a shift in precession frequency associated with the presence of a non-zero nEDM in a large electric field. To achieve the desired sensitivity, the spectrometer must be designed to minimize systematic uncertainties. The calculations and simulations described here demonstrate the requirements to achieve this goal. This work is largely focused on the design of the central region of the spectrometer, which contains the UCNs and applies the electric field. The work done on the central region includes the development of a prototype cell and characterization of its storage properties, simulation studies of the electric fields and impact of magnetic properties, and measurements of ferromagnetic contamination in components of the central region.

Text

2025-04-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90801

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/