Dense, room-temperature polarized nuclear targets using SABRE chemical hyperpolarization

Polarized nuclear targets are a crucial tool in particle physics experiments for accessing spin-dependent observables. Current experiments use dynamic nuclear polarization (DNP) to generate high levels of spin order, achieving polarization levels in excess of 90% for the 1H nucleus. While DNP targets have been very successful, they suffer from depolarization effects with high intensity beams and thus are unable to be used at the intensity frontier with the upcoming generation of accelerator facilities.
This thesis assesses the capability of a recently developed nuclear polarization technique, Signal Amplification By Reversible Exchange (SABRE), to address the issues facing DNP targets. SABRE catalytically converts the high spin order of parahydrogen into nuclear spin polarization. It operates in the solution state at room temperature within weak applied fields, generating the polarization on timescales of seconds.
Chapter 2 assesses the factors that affect polarization transfer efficiency through SABRE, also presenting the synthesis of a novel selectively-deuterated substrate for SABRE, 3,5-pyridine-d2. In Chapter 3, the factors affecting spin order relaxation in SABRE substrates are investigated, finding that the minimal rate of spin order relaxation for 3,5-dichloropyridine is achieved at close to room temperature and in fields not exceeding 1 tesla. Chapter 4 presents the first in-beam measurements of the resilience of SABRE-polarized material to an incident particle beam, performed at the Mainz Microtron facility. Here it is found that there is no evidence for a depolarizing effect in the samples subject to the A2 photon beam, and that a sample subject to a high radiation dose from proximity to the electron beam dump in the A2 Hall exhibited significant repolarizability. In Chapter 5, the development and performance of a prototype SABRE-polarized target is presented, with polarization levels in excess of 20% being achieved with the substrate 3,5-pyridine-d2.