New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a OneElectron Quantum Cyclotron
Abstract
Remarkably, the famous UW measurement of the electron magnetic moment has stood since 1987. With QED theory, this measurement has determined the accepted value of the fine structure constant. This colloquium is about a new Harvard measurement of these fundamental constants. The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations. One electron suspended in a Penning trap is used for the new measurement, like in the old measurement. What is different is that the lowest quantum levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy. In addition, a 0.1 mK Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state. Finally, great signaltonoise for onequantum transitions is obtained using electronic feedback to realize the first oneparticle selfexcited oscillator. The new methods may also allow a million times improved measurement of the 500 times small antiproton magnetic moment.
 Authors:
 Harvard University, Cambridge, Massachusetts, United States
 Publication Date:
 Research Org.:
 FNAL (Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States))
 Sponsoring Org.:
 USDOE Office of Science (SC)
 OSTI Identifier:
 987201
 DOE Contract Number:
 AC0207CH11359
 Resource Type:
 Multimedia
 Resource Relation:
 Conference: Fermilab Colloquia, Fermi National Accelerator Laboratory (FNAL), Batvia, Illinois (United States), presented on January 24, 2007
 Country of Publication:
 United States
 Language:
 English
 Subject:
 43 PARTICLE ACCELERATORS
Citation Formats
Gabrielse, Gerald. New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a OneElectron Quantum Cyclotron. United States: N. p., 2007.
Web.
Gabrielse, Gerald. New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a OneElectron Quantum Cyclotron. United States.
Gabrielse, Gerald. Wed .
"New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a OneElectron Quantum Cyclotron". United States.
doi:. https://www.osti.gov/servlets/purl/987201.
@article{osti_987201,
title = {New Measurement of the Electron Magnetic Moment and the Fine Structure Constant: A First Application of a OneElectron Quantum Cyclotron},
author = {Gabrielse, Gerald},
abstractNote = {Remarkably, the famous UW measurement of the electron magnetic moment has stood since 1987. With QED theory, this measurement has determined the accepted value of the fine structure constant. This colloquium is about a new Harvard measurement of these fundamental constants. The new measurement has an uncertainty that is about six times smaller, and it shifts the values by 1.7 standard deviations. One electron suspended in a Penning trap is used for the new measurement, like in the old measurement. What is different is that the lowest quantum levels of the spin and cyclotron motion are resolved, and the cyclotron as well as spin frequencies are determined using quantum jump spectroscopy. In addition, a 0.1 mK Penning trap that is also a cylindrical microwave cavity is used to control the radiation field, to suppress spontaneous emission by more than a factor of 100, to control cavity shifts, and to eliminate the blackbody photons that otherwise stimulate excitations from the cyclotron ground state. Finally, great signaltonoise for onequantum transitions is obtained using electronic feedback to realize the first oneparticle selfexcited oscillator. The new methods may also allow a million times improved measurement of the 500 times small antiproton magnetic moment.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 24 00:00:00 EST 2007},
month = {Wed Jan 24 00:00:00 EST 2007}
}

A new measurement resolves the cyclotron and spin levels for a singleelectron quantum cyclotron to obtain a dimensionless electron magnetic moment, g, to 7.6 parts in 1013 (nearly six times better than in the past) and shifted by 1.7 standard deviations. The new g, with a quantum electrodynamics (QED) calculation, determines the fine structure constant with a 0.7 ppb uncertainty  ten times smaller than for atomrecoil determinations. Remarkably, this 100 mK measurement probes for internal electron structure at 130 GeV.

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