Measurement of the positive muon lifetime and determination of the Fermi constant to part-per-million precision
We report a measurement of the positive muon lifetime to a precision of 1.0 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 2×1012 decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τμ+(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: GF(MuLan)=1.1663788(7) ×10-5GeV-2 (0.6 ppm). It is also used to extract the μ-p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling gP. © 2011 American Physical Society.
Webber, D. M.; Tishchenko, V.; Peng, Q.; Battu, S.; Carey, R. M.; Chitwood, D. B.; Crnkovic, J.; Debevec, P. T.; Dhamija, S.; Earle, W.; Gafarov, A.; Giovanetti, K.; Gorringe, T. P.; Gray, F. E.; Hartwig, Z.; Hertzog, D. W.; Johnson, B.; Kammel, P.; Kiburg, B.; Kizilgul, S.; Kunkle, J.; Lauss, B.; Logashenko, I.; Lynch, K. R.; McNabb, R.; Miller, J. P.; Mulhauser, F.; Onderwater, C. J.G.; Phillips, J.; Rath, S.; Roberts, B. L.; Winter, P.; and Wolfe, B., "Measurement of the positive muon lifetime and determination of the Fermi constant to part-per-million precision" (2011). Regis University Faculty Publications. 833.