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Joined 2026-09-21 Message
Incoming links: Henry Michael Foley
Kusch-Foley magnetic moment experiment 2026-10-18
Polykarp Kusch and Henry Michael Foley compared hyperfine structure resonance frequencies for different electronic states of gallium, indium and sodium. Their 1948 paper reports mutually consistent departures from the ratios expected with orbital factor and spin factor . Comparing several states constrained the alternative explanation of perturbed atomic levels.[ref]
The Magnetic Moment of the Electron by Polykarp Kusch and Henry Michael Foley (1948). Abstract: atomic states, frequency comparisons and interpretation
The Rabi molecular beam magnetic resonance experiment explains the readout principle: a resonant transition changes an atom's magnetic response, and hence its transmitted beam signal. Kusch describes rapidly interchangeable ovens, several radio frequency oscillators and careful field homogenization. Measurements taken during monotonic field drift were reduced to a common field.[ref]
The magnetic moment of the electron by Polykarp Kusch. pp. 303–304: resonance analysis, ovens, oscillators and field drift
Compare differently weighted atomic magnetic moments
. Original functional diagram of the Kusch-Foley magnetic moment experiment and a separate ideal LS coupling calculation. The upper flow identifies the functions of beam preparation, resonance readout and atomic modeling; it is not a surviving apparatus drawing. The lower weights are calculated for , , and chosen , without nuclear spin. The frequencies in the teaching model cannot be substituted directly for measured hyperfine lines. Details.
Real hyperfine structure lines are not simply bare electronic times field. Nuclear magnetic moments, known interaction constants and nonlinear field dependence enter the inference.[ref]
The magnetic moment of the electron by Polykarp Kusch. pp. 303–305: hyperfine modeling and atomic-state perturbations
Field homogeneity controls line broadening; alternating species addresses drift. Neither control removes an error in the atomic model. The beauty of the comparison is the separation of two problems: cancelling a shared calibration scale and testing whether several physical systems imply the same electron spin g-factor.