Phys. Rev. Lett. 106, 041803 (2011) - Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision

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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 $2 \times 10^{12}$ 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: $G_{F} (MuLan) = 1.166 378 8 (7) \times 10^{- 5} {GeV}^{- 2}$ (0.6 ppm). It is also used to extract the $μ^{-} p$ singlet capture rate, which determines the proton’s weak induced pseudoscalar coupling $g_{P}$ .

DOI: dx.doi.org/10.1103/PhysRevLett.106.041803

Received 5 October 2010
Published 25 January 2011
Corrected 7 February 2011

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Publisher’s Note: Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision [Phys. Rev. Lett. 106, 041803 (2011)]

D. M. Webber et al. (MuLan Collaboration)

Phys. Rev. Lett. 106, 079901 (2011)

Authors & Affiliations

Experimental Constraints on Left-Right Symmetric Models from Muon Decay

R. Bayes et al. (TWIST Collaboration)

Phys. Rev. Lett. 106, 041804 (2011)

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Figure 1
Diagram of the experiment. Muons are transported to the AK-3 or quartz disk targets through a vacuum beam pipe, which is lined on the inside with 0.1-mm-thick AK-3 foils polarized in the azimuthal direction. 170 pairs of triangular scintillator detectors, each read out individually, surround the target. The Halbach magnetic ring is used only for the quartz disk. A wire chamber (EMC) is placed at the rear to monitor the beam profile when the targets are opened.
Figure 2
Lifetime measurement summary. The MuLan R06 and R07 results are plotted separately to illustrate the consistency. The vertical shaded band is centered on the MuLan weighted average with a width equal to the combined uncertainty.

Physical Review Letters

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

Phys. Rev. Lett. 106, 041803 – Published 25 January 2011; Erratum Phys. Rev. Lett. 106, 079901 (2011)

D. M. Webber et al. (MuLan Collaboration)

Abstract

Article Available via CHORUS

Erratum

Publisher’s Note: Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision [Phys. Rev. Lett. 106, 041803 (2011)]

D. M. Webber et al. (MuLan Collaboration)

Phys. Rev. Lett. 106, 079901 (2011)

Authors & Affiliations

See Also

Experimental Constraints on Left-Right Symmetric Models from Muon Decay

R. Bayes et al. (TWIST Collaboration)

Phys. Rev. Lett. 106, 041804 (2011)

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Physical Review Letters

moving physics forward

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

Phys. Rev. Lett. 106, 041803 – Published 25 January 2011; Erratum Phys. Rev. Lett. 106, 079901 (2011)

D. M. Webber et al. (MuLan Collaboration)

Abstract

Article Available via CHORUS

Erratum

Publisher’s Note: Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision [Phys. Rev. Lett. 106, 041803 (2011)]

D. M. Webber et al. (MuLan Collaboration)

Phys. Rev. Lett. 106, 079901 (2011)

Authors & Affiliations

See Also

Experimental Constraints on Left-Right Symmetric Models from Muon Decay

R. Bayes et al. (TWIST Collaboration)

Phys. Rev. Lett. 106, 041804 (2011)

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References (Subscription Required)

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