Frequency shifts in the EPR spectrum of $^{39}$K due to spin-exchange collisions with polarized $^3$He and precise $^3$He polarimetry
| Autor: | Katugampola, Sumudu, Jantzi, Christopher, Keder, David A., Miller, G. Wilson, Nelyubin, Vladimir, Nguyen, Huong, Tafti, Sina, Tobias, William A., Cates, Gordon D. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The Zeeman splittings and EPR frequencies of alkali-metal atoms are shifted in the presence of a polarized noble gas. For a spherical geometry, the shift is enhanced over what is expected classically by a dimensionless atomic parameter $\kappa_0$ that is unique to each alkali-metal atom - noble-gas pair. We present a precise measurement of $\kappa_0$ for the $^{39}$K-$^3$He system with a relative accuracy of better than 1\%. A critical component of achieving sub-percent accuracy involved characterizing the shape of our samples using both MRI and CT medical-imaging techniques. The parameter $\kappa_0$ plays an important role in establishing the absolute polarization of $^3$He in a variety of contexts, including polarized targets for electron scattering experiments and MRI of the gas space of the lungs. Our measurement more than doubles the accuracy possible when using $\kappa_0$ for polarimetry purposes. Just as important, the work presented here represents the first {\it direct} measurement of $\kappa_0$ for the $^{39}$K-$^3$He system; previous values for $\kappa_0$ in the $^{39}$K-$^3$He system relied on a chain of measurements that were benchmarked by previous measurements of $\kappa_0$ in the Rb-$^3$He system. Comment: 18 pages, 15 figures |
| Databáze: | arXiv |
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