Measurement of the Lifetime of the Positive Pion

Abstract

Using fast electronic techniques, we have observed the $\pi \mu e$ decay sequence for about ${10}^8$ stopped positive $\pi$-mesons. The exponential decay of the $\pi$ can be followed for 8 mean lives, and yields a value of ${{\tau }_{\pi }}^{+}=26.40\mathrm{}\pm 0.08$ nsec. This value disagrees with previously reported values.