Direct measurement of the He-3(+) magnetic moments

Article

关键词: HYPERFINE-STRUCTURE;    GROUND-STATE;    PENNING TRAP;    HYDROGEN;    PROTON;    ACCURACY;    ELECTRON;    MASS;   

DOI  :  10.1038/s41586-022-04761-7

来源: SCIE

【 摘 要 】

Helium-3 has nowadays become one of the most important candidates for studies in fundamental physics(1-3), nuclear and atomic structure(4,5), magnetometry and metrology(6), as well as chemistry and medicine(7,8). In particular, He-3 nuclear magnetic resonance (NMR) probes have been proposed as a new standard for absolute magnetometry(6,)(9). This requires a high-accuracy value for the He-3 nuclear magnetic moment, which, however, has so far been determined only indirectly and with a relative precision of 12 parts per billon(10,)(11). Here we investigate the He-3(+) ground-state hyperfine structure in a Penning trap to directly measure the nuclearg-factor of He-3(+) g(I)' = -4.2550996069(30)(stat)(17)(sys), the zero-field hyperfine splitting E-HFS(exp) = -8,665,649,865.77(26)(stat) (1)(sys )Hz and the bound electrong-factor g(e)(exp) = -2.00217741579(34)(stat)(30)(sys). The latter is consistent with our theoretical value g(e)(theo) = - 2.00217741625223(39) based on parameters and fundamental constants from ref.(12). Our measured value for the He-3(+) nuclearg-factor enables determination of the g-factor of the bare nucleus g(I) = -4 .255250 6997 (30)(stat)(17)(sys)(1)(theo) via our accurate calculation of the diamagnetic shielding constant(13 )sigma(3)(He+) = 0.00003550738(3). This constitutes a direct calibration for He-3 NMR probes and an improvement of the precision by one order of magnitude compared to previous indirect results. The measured zero-field hyperfine splitting improves the precision by two orders of magnitude compared to the previous most precise value(14) and enables us to determine the Zemach radius (15)to r(Z) = 2.608(24) fm.

【 授权许可】

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