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Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision

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 نشر من قبل David W. Hertzog
 تاريخ النشر 2010
  مجال البحث
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We report a measurement of the positive muon lifetime to a precision of 1.0 parts per million (ppm); it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2 x 10^{12} decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give tau_{mu^+}(MuLan) = 2196980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G_F(MuLan) = 1.1663788 (7) x 10^-5 GeV^-2 (0.6 ppm). It is also used to extract the mu^-p singlet capture rate, which determines the protons weak induced pseudoscalar coupling g_P.



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219 - David M. Webber 2011
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378 - T. P. Gorringe 2013
We report results from the MuLan measurement of the positive muon lifetime. The experiment was conducted at the Paul Scherrer Institute using a time-structured surface muon beam and a segmented plastic scintillator array. Two different in-vacuum muon stopping targets were used: a ferromagnetic foil with a large internal magnetic field and a quartz crystal in a moderate external magnetic field. From a total of 1.6 x 10^{12} decays, we obtained the muon lifetime tau_mu = 2196980.3(2.2) ps (1.0 ppm) and Fermi constant G_F = 1.1663787(6) x 10^{-5} GeV^{-2} (0.5 ppm).
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