Improved measurement of the positive-muon lifetime and determination of the fermi constant

D. B. Chitwood, T. I. Banks, M. J. Barnes, S. Battu, R. M. Carey, S. Cheekatmalla, S. M. Clayton, J. Crnkovic, K. M. Crowe, P. T. Debevec, S. Dhamija, W. Earle, A. Gafarov, K. Giovanetti, T. P. Gorringe, F. E. Gray, M. Hance, D. W. Hertzog, M. F. Hare, P. KammelB. Kiburg, J. Kunkle, B. Lauss, I. Logashenko, K. R. Lynch, R. McNabb, J. P. Miller, F. Mulhauser, C. J.G. Onderwater, C. S. Özben, Q. Peng, C. C. Polly, S. Rath, B. L. Roberts, V. Tishchenko, G. D. Wait, J. Wasserman, D. M. Webber, P. Winter, P. A. Zołnierczuk

Research output: Contribution to journalArticlepeer-review

74 Scopus citations


The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, τμ=2.197013(24)μs, is in excellent agreement with the previous world average. The new world average τμ=2.197019(21)μs determines the Fermi constant GF=1.166371(6)×10-5GeV-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling gP.

Original languageEnglish
Article number032001
JournalPhysical Review Letters
Issue number3
StatePublished - Jul 16 2007

ASJC Scopus subject areas

  • General Physics and Astronomy


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