Determination of γ′P at the National Bureau of Standards
The gyromagnetic ratio of the proton, γ′P is one of our most important fundamental physical constants. (The prime indicates that the protons are in a spherical sample of pure H2O.) Not only is it used for calibration purposes in nuclear magnetic resonance experiments, but it plays a crucial role in determining the fine structure constant from the measurement of 2e/h via the ac Josephson effect (1). Additionally the continued measurement of γ′P can be used to monitor as-maintained units of current (2).
KeywordsAngular Position Nuclear Magnetic Resonance Experiment Diameter Variation Frequency Synthesizer Precession Frequency
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