The Lifetime of the Positiveπ-Meson

Abstract

The lifetime of the positive $\pi$-meson has been measured using a method similar to that used by Richardson in his measurement of the negative $\pi$-meson. The lifetime obtained is $\tau =1.97\mathrm{}\pm \times {10}^{-8\mathrm{}}$ sec. or ${\tau }_{\frac{1}{2}}=1.37\mathrm{}\pm \times {10}^{-8\mathrm{}}$ sec. These values are about 2.5 probable errors from Richardson's value of $\tau =7.7\mathrm{}\pm \times {10}^{-9\mathrm{}}$ sec. The method has been extended so that two points on a decay curve could be determined and the geometry of the system determined to better accuracy. The geometry of the apparatus was checked by measuring the effective "lifetime" of the $\alpha$-particles in the same configuration; this was found to be greater than 0.5 × ${10}^{-6\mathrm{}}$ sec.