New Measurement of the Electron Magnetic Moment Using a One-Electron Quantum Cyclotron (original) (raw)
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Highly Accurate Measurement of the Electron Orbital Magnetic Moment
arXiv (Cornell University), 2015
We propose to accurately determine the orbital magnetic moment of the electron by measuring, in a Magneto-Optical or Ion trap, the ratio of the Lande g-factors in two atomic states. From the measurement of (g J1 /g J2), the quantity A = (αδ S-βδ L) can be extracted, if the states are LS coupled. The indirectly measured quantity is a linear combination of the δ S and δ L which are, respectively, the corrections to the spin and orbital g-factors where α, β are constants. Given that highly accurate values of δs are currently available, accurate values of δ L may also be determined. At present, the correction δ L = (-1.8 ± 0.4) x 10-4 has been determined by using earlier measurements of the ratio of the g-factors, made on the Indium 2 P 1/2 and 2 P 3/2 states.
Theory of the Anomalous Magnetic Moment of the Electron
Atoms, 2019
The anomalous magnetic moment of the electron a e measured in a Penning trap occupies a unique position among high precision measurements of physical constants in the sense that it can be compared directly with the theoretical calculation based on the renormalized quantum electrodynamics (QED) to high orders of perturbation expansion in the fine structure constant α, with an effective parameter α/π. Both numerical and analytic evaluations of a e up to (α/π) 4 are firmly established. The coefficient of (α/π) 5 has been obtained recently by an extensive numerical integration. The contributions of hadronic and weak interactions have also been estimated. The sum of all these terms leads to a e (theory) = 1 159 652 181.606 (11)(12)(229) × 10 −12 , where the first two uncertainties are from the tenth-order QED term and the hadronic term, respectively. The third and largest uncertainty comes from the current best value of the fine-structure constant derived from the cesium recoil measurement: α −1 (Cs) = 137.035 999 046 (27). The discrepancy between a e (theory) and a e ((experiment)) is 2.4σ. Assuming that the standard model is valid so that a e (theory) = a e (experiment) holds, we obtain α −1 (a e) = 137.035 999 1496 (13)(14)(330), which is nearly as accurate as α −1 (Cs). The uncertainties are from the tenth-order QED term, hadronic term, and the best measurement of a e , in this order.
Physical Review Letters, 2000
We present a new experimental value for the magnetic moment of the electron bound in hydrogenlike carbon ͑ 12 C 51 ͒: g exp 2.001 041 596 ͑5͒. This is the most precise determination of an atomic g J factor so far. The experiment was carried out on a single 12 C 51 ion stored in a Penning trap. The high accuracy was made possible by spatially separating the induction of spin flips and the analysis of the spin direction. The current theoretical value amounts to g th 2.001 041 591 ͑7͒. Together experiment and theory test the bound-state QED contributions to the g J factor of a bound electron to a precision of 1%.
Precision Measurement of the Electron/Muon Gyromagnetic Factors
2010
Clear, persuasive arguments are brought forward to motivate the need for highly precise measurements of the electron/muon orbital g, i.e. gL. First, we briefly review results obtained using an extended Dirac equation, which conclusively showed that, as a consequence of quantum relativistic corrections arising from the time-dependence of the rest-energy, the electron gyromagnetic factors are corrected. It is next demonstrated, using the data of Kusch & Foley on the measurement of deltaS minus 2 deltaL together with the modern precise measurements of the electron deltaS where deltaS identically equal to gS minus 2, that deltaL may be a small, non-zero quantity, where we have assumed Russel-Saunders LS coupling and proposed, along with Kusch and Foley, that gS = 2 plus deltaS and gS = 1 plus deltaL. Therefore, there is probable evidence from experimental data that gS is not exactly equal to 1; the expectation that quantum effects will significantly modify the classical value of the orb...
Electron Magnetic Moment in Highly Charged Ions: The ARTEMIS Experiment
Annalen der Physik, 2018
The magnetic moment (g-factor) of the electron is a fundamental quantity in physics that can be measured with high accuracy by spectroscopy in Penning traps. Its value has been predicted by theory, both for the case of the free (unbound) electron and for the electron bound in a highly charged ion. Precision measurements of the electron magnetic moment yield a stringent test of these predictions and can in turn be used for a determination of fundamental constants such as the fine structure constant or the atomic mass of the electron. For the bound-electron magnetic-moment measurement, two complementary approaches exist, one via the so-called "continuous Stern-Gerlach effect", applied to ions with zero-spin nuclei, and one a spectroscopic approach, applied to ions with nonzero nuclear spin. Here, the latter approach is detailed, and an overview of the experiment and its status is given.
Magnetic moment of a bound electron
Nuclear Physics B - Proceedings Supplements, 2010
Theoretical predictions underlying determinations of the fine structure constant α and the electron-to-proton mass ratio me/mp are reviewed, with the emphasis on the bound electron magnetic anomaly g − 2. The theory of the interaction of hydrogen-like ions with a magnetic field is discussed. The status of efforts aimed at the determination of O α(Zα) 5 and O α 2 (Zα) 5 corrections to the g factor is presented. The reevaluation of analogous corrections to the Lamb shift and the hyperfine splitting is summarized.
High precision beam momentum determination in a synchrotron using a spin-resonance method
Physical Review Special Topics - Accelerators and Beams, 2010
In order to measure the mass of the η meson with high accuracy using the dp → 3 He η reaction, the momentum of the circulating deuteron beam in the Cooler Synchrotron COSY of the Forschungszentrum Jülich has to be determined with unprecedented precision. This has been achieved by studying the spin dynamics of the polarized deuteron beam. By depolarizing the beam through the use of an artificially induced spin resonance, it was possible to evaluate its momentum p with a precision of ∆p/p < 10 −4 for a momentum of roughly 3 GeV/c. Different possible sources of error in the application of the spin-resonance method are discussed in detail and its possible use during a standard experiment is considered.
Quantitative magnetic measurements with transmission electron microscope
Journal of Magnetism and Magnetic Materials, 2010
We briefly review the state-of-the-art electron magnetic chiral dichroism experiments and theory with focus on quantitative measurements of the atom-specific orbital to spin moment ratio m l =m s . Our approach of quantitative method, based on reciprocal space mapping of the magnetic signal, is described. We discuss additional symmetry considerations for m l =m s measurements, which are present due to dynamical diffraction effects. These lead to a preference for the 3-beam orientation of the sample. Further on, we describe a method of correcting asymmetries present due to imperfect 3-beam orientation-the so-called double-difference correction.
Comparison of the electron and positron anomalous magnetic moments: Experiment 1987
Physics Letters B, 1987
The anomalous magnetic moments of relativistic electrons and positrons have been compared by measuring the spin precession phase difference at a given time interval. The difference in the anomalous magnetic moments between the electron and the positron has been shown to lie within 1 X 10-8 at 95% confidence level, which improves the accuracy of the previous measurements by an order of magnitude.
New determination of the electron's mass
Physical review letters, 2001
for many enlightening and stimulating discussions. Financial support was obtained from the European Union under the contract number ERB FMRX CT 97-0144 (EUROTRAPS network).