2014/05/27 by A. Mooser, S. Ulmer, K. Blaum +8 · 2 citations
Physics and Astronomy · #Atomic and Molecular Physics #Atomic physics #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Cyclotron #Electron #Electron magnetic dipole moment #Gyromagnetic ratio #Magnetic field #Magnetic moment #Magnetization #Neutron magnetic moment #Nuclear magnetic moment #Nuclear physics #Nuclear physics research studies #Penning trap #Physics #Proton #Proton magnetic moment #Quantum mechanics #physics.atom-ph #quant-ph
paper · pdf · doi:10.1038/nature13388
published as Nature 509 (2014) 596-599 · published in Nature
openalex publication_date 2014/05/27 · arxiv created 2014/06/18 · arxiv updated 2014/06/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The spin-magnetic moment of the proton μp is a fundamental property of this particle. So far μp has only been measured indirectly, analysing the spectrum of an atomic hydrogen maser in a magnetic field. Here, we report the direct high-precision measurement of the magnetic moment of a single proton using the double Penning-trap technique. We drive proton-spin quantum jumps by a magnetic radio-frequency field in a Penning trap with a homogeneous magnetic field. The induced spin-transitions are detected in a second trap with a strong superimposed magnetic inhomogeneity. This enables the measurement of the spin-flip probability as a function of the drive frequency. In each measurement the proton's cyclotron frequency is used to determine the magnetic field of the trap. From the normalized resonance curve, we extract the particle's magnetic moment in units of the nuclear magneton μp=2.792847350(9)μN. This measurement outperforms previous Penning trap measurements in terms of precision by a factor of about 760. It improves the precision of the forty year old indirect measurement, in which significant theoretical bound state corrections were required to obtain μp, by a factor of 3. By application of this method to the antiproton magnetic moment μ_p the fractional precision of the recently reported value can be improved by a factor of at least 1000. Combined with the present result, this will provide a stringent test of matter/antimatter symmetry with baryons.