TOPICS IN NMR POLARIZATION MEASUREMENT

Using a precise circuit theoretical treatment of the series Q-meter, a nalytical expressions are derived for the relationship between the exp erimental NMR signal and the RF susceptibility on one hand, and their integrals and the polarization on the other. These are used for the ab initio calculation of the signal-to-noise ratio for deuteron targets, which yield a realistic ultimate calibration precision of 0.1% at 1 K . The experimental signal distortions and drift are discussed, which l ead to proposed optimized tuning and design rules, improved circuits, and new applications. Among these are the measurement of N-14 polariza tion in irradiated NH3 targets, and the improvement of the temperature scale around 1 K by one order of magnitude.