Precision Mass Spectroscopy of the Antiproton and Proton Using Simultaneously Trapped Particles

Phys. Rev. Lett. 82, 3198 – Published 19 April 1999
G. Gabrielse, A. Khabbaz, D. S. Hall, C. Heimann, H. Kalinowsky, and W. Jhe


This last of a series of three measurements improves the comparison of antiproton (p¯) and proton (p) by almost a factor of 106 over earlier exotic atom measurements, and is the most precise CPT test with baryons by a similar large factor. Measuring the cyclotron frequencies of a simultaneously trapped p¯ and H- ion establishes that the ratio of q/m for p¯ and p is -0.999 999 999 91±0.000 000 000 09, more than 10 times the accuracy over our previous measurement. This 9×10-11 comparison makes the first use of simultaneously trapped particles for sub-ppb spectroscopy.


  • Received 10 November 1998
  • Published in the issue dated 19 April 1999

© 1999 The American Physical Society

Authors & Affiliations

G. Gabrielse, A. Khabbaz, and D. S. Hall*

  • Department of Physics, Harvard University, Cambridge, Massachusetts 02138

C. Heimann and H. Kalinowsky

  • Institut für Strahlen- und Kernphysik, University of Bonn, 53115 Bonn, Germany

W. Jhe

  • Department of Physics, Seoul National University, 151-742 Seoul, Korea

  • *Current address: CB440, JILA, Boulder, Colorado.

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