Time Dependence of the Decay Energy Spectrum for Stopped Cosmic-Ray Particles at Sea Level

Within the indicated standard statistical uncertainties, the mean life (τ) for particles of the sea-level cosmic-ray muon beam, stopped in carbon, is independent of the decay energy classification (E in MeV). τ(29>E>11)τ(50>E>29)=1.01+/-0.03, τ(66>E>43)τ(E>26)=1.07+/-0.05, τ(E>26)=(2.109+/-0.032) μ.