Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant

Authors :: MuLan Collaboration
Chitwood, D. B.
Banks, T. I.
Barnes, M. J.
Battu, S.
Carey, R. M.
Cheekatmalla, S.
Clayton, S. M.
Crnkovic, J.
Crowe, K. M.
Debevec, P. T.
Dhamija, S.
Earle, W.
Gafarov, A.
Giovanetti, K.
Gorringe, T. P.
Gray, F. E.
Hance, M.
Hertzog, D. W.
Hare, M. F.
Kammel, P.
Kiburg, B.
Kunkle, J.
Lauss, B.
Logashenko, I.
Lynch, K. R.
McNabb, R.
Miller, J. P.
Mulhauser, F.
Onderwater, C. J. G.
Ozben, C. S.
Peng, Q.
Polly, C. C.
Rath, S.
Roberts, B. L.
Tishchenko, V.
Wait, G. D.
Wasserman, J.
Webber, D. M.
Winter, P.
Zolnierczuk, P. A.
Source :: Phys.Rev.Lett.99:032001,2007
Publication Year :: 2007
Abstract: 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, tau_mu = 2.197013(24) us, is in excellent agreement with the previous world average. The new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F = 1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.<br />Comment: As published version (PRL, July 2007)

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