The Energy Spectrum of Positrons from the Decay of theμ-Meson

The energy of the positrons from 301π→μ→β decays have been determined in electron sensitive emulsions by measuring the multiple scattering of the positron tracks. The annihilation properties of the charged particle emitted in the decay of the μ⁺ meson confirm its identity as a positron. This spectrum has a maximum about 36 Mev and a nonzero cutoff at the high energy end. A statistical analysis of the data, using the Michel theory, yields a value of ρ=0.41±0.13.