Precision Polarimetry of Solid HD Photonuclear Targets at LEGS

摘要

We have constructed and operated a NMR polarimeter for high-accuracy measurements of hydrogen and deuterium polarization in a frozen-spin solid HD photonuclear physics target. The heart of this polarimeter is a pair of crossed (orthogonal) RF coils that form a transformer that responds only to precessing spins in the sample. We have performed a complete electronic circuit analysis of this crossed coil polarimeter (CC-Meter), and have determined the optimum conditions for its operation. From this analysis, which is confirmed by NMR measurements on hydrogen and deuterium in solid HD, we conclude that the CC-meter can be operated to give a very high signal-to-noise ratio (SNR) for thermal equilibrium polarization while also producing a highly linear response for fully polarized targets. In general, we find that a well-designed and properly constructed CC-Meter can provide a larger SNR at similar non-linearity, compared to the more commonly used Q-meter. We have used this polarimeter to produce H polarization measurements for a new, high precision determination of the GDH integral for the proton.