Measurement of the positive muon lifetime and determination of the Fermi constant to part-per-million precision

Phys Rev Lett. 2011 Jan 28;106(4):041803. doi: 10.1103/PhysRevLett.106.041803. Epub 2011 Jan 25.

Abstract

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 2×10(12) decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τ(μ(+)) (MuLan)=2 196 980.3(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)=1.166 378 8(7)×10(-5) GeV(-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 g(P).

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.