Author ORCID Identifier
Date Available
5-12-2023
Year of Publication
2023
Degree Name
Doctor of Philosophy (PhD)
Document Type
Doctoral Dissertation
College
Arts and Sciences
Department/School/Program
Physics and Astronomy
First Advisor
Dr. Brad Plaster
Abstract
Charge-Parity (CP) violation is one of Sakharov's three conditions which serve as guidelines for the generation of a matter-antimatter asymmetry in the early universe. The Standard Model (SM) of particle physics contains sources of CP violation which can be used to predict the baryon asymmetry. The observed baryon asymmetry is not predicted from SM calculations, meaning there must be additional sources of CP violation beyond the Standard Model (BSM) to generate the asymmetry. Permanent electric dipole moments (EDMs), which are inherently parity- and time reversal- violating, present a promising avenue for the discovery of new sources of CP violation to resolve this outstanding problem. The SM prediction for the neutron EDM, for example, is multiple orders of magnitude smaller than the sensitivity achieved by modern neutron EDM experiments \cite{sm_nedm_estimate}. The measurement of a non-zero neutron electric dipole moment larger than the SM prediction would be a sure sign of BSM CP violation. A experiment searching for the neutron EDM at Los Alamos National Lab (LANL) has been constructed with the goal of improving the current neutron EDM upper limit $d_n < 1.8 \times 10^{-26} \; e \cdot$cm (90\% CL) \cite{ILL-nEDM-2020} by approximately one order of magnitude. The work presented in this thesis has been performed in support of the LANL-nEDM experimental effort.
Precise magnetic field control is required to reach the desired measurement sensitivity, specifically a highly uniform $B_0$ holding magnetic field. A multiple-split solenoid with an octagonal cross section was designed and fabricated to meet the gradient specification $\langle | \partial B_z / \partial z | \rangle < 0.3$ nT/m and address engineering challenges related to assembly and magnetometry. Efficient transport of neutron polarization from the polarizing magnet to the storage cells is also essential to accomplish the sensitivity goal. A series of modified, self-shielding cos $\theta$ coils have been designed to maximize polarization as neutrons propagate through penetrations in the magnetically shielded room. The spin-transport coils, in conjunction with the simultaneous spin analyzers, will provide a polarization product $\alpha > 0.8$. The series of coils interfaces with the $B_0$ coil in a pseudo-continuous manner such that the fringe fields do not cause depolarization of the neutrons and do not generate non-uniformities in the storage cell volumes.
Digital Object Identifier (DOI)
https://doi.org/10.13023/etd.2023.226
Funding Information
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-SC0014622, the NSF under Award Number PHY-1828568, the LANL LDRD program, and by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE‐SC0014664.
Recommended Citation
Brewington, Jared, "Design of the Highly Uniform Magnetic Field and Spin-Transport Magnetic Field Coils for the Los Alamos National Lab Neutron Electric Dipole Moment Experiment" (2023). Theses and Dissertations--Physics and Astronomy. 113.
https://uknowledge.uky.edu/physastron_etds/113
