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Double-trap measurement of the proton magnetic moment at 0.3 parts per billion precision

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Science  24 Nov 2017:
Vol. 358, Issue 6366, pp. 1081-1084
DOI: 10.1126/science.aan0207
  • Fig. 1 Measurements of the g factor.

    Shown are the most precise direct and indirect measurements of the proton g factor (4, 7), which also largely determine the currently accepted CODATA value (29), also shown. This work improves on the measurement from 2014 by a factor of 11. The first pioneering measurements at ppm resolution (19, 34) are not shown.

  • Fig. 2 Measurement setup and cycle.

    (A) Magnetic field on axis with magnetic bottle in the analysis trap. A residual magnetic field inhomogeneity B2,PT is still present in the precision trap despite the distance of 54.25 mm between the two traps. (B) Sectional cut through the cylindrical copper electrodes of the double–Penning trap system. Each trap is connected to detectors to measure the proton eigenfrequencies. The precision trap is surrounded by a superconducting self-shielding coil to reduce external magnetic field fluctuations. (C) Flow diagram of the measurement cycle. See text for details.

  • Fig. 3 Resonance of the g factor.

    The red line shows the final g-factor resonance obtained from 1264 accumulated data points. The Gaussian line shape is calculated from a maximum likelihood analysis (see supplementary materials) that does not require explicit binning of the data. Also shown are representative data points with 1σ error bars. The dark and light gray bands indicate SEM on the g factor and on the spin-flip amplitude, respectively. The vertical lines show the mean value shifted by the assigned uncertainty.

  • Table 1 Systematic corrections.

    The table summarizes all systematic corrections with uncertainty. The total error is obtained by linearly summing all errors to conservatively account for correlations.

    ParameterRelative shift on g/2 (ppt)Error (ppt)
    Trapping potential09
    Magnetic inhomogeneity84
    Relativistic shift−4426
    Image current11
    Image charge−983
    Fitting080
    Total−133123

Supplementary Materials

  • Double-trap measurement of the proton magnetic moment at 0.3 parts per billion precision

    Georg Schneider, Andreas Mooser, Matthew Bohman, Natalie Schön, James Harrington, Takashi Higuchi, Hiroki Nagahama, Stefan Sellner, Christian Smorra, Klaus Blaum, Yasuyuki Matsuda, Wolfgang Quint, Jochen Walz, Stefan Ulmer

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

    Download Supplement
    • Materials and Methods
    • Figs. S1 to S3
    • References

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