Differential Measurement of the Meson Lifetime

Measurements of the meson lifetime were made by comparing the lead absorption curves of the cosmic radiation at two different elevations, and by compensating the air column at the higher level by a layer of graphite placed on top of the counter telescope. The method does not require any knowledge of the energy distribution or of the height of the producing layer of the mesons. All systematic errors are greatly reduced by the differential method used and can be shown to be insignificant. The value of the lifetime comes out to be appreciably shorter than in previous determinations, viz. $(1.25\mathrm{}\pm 0.3)\times {10}^{-6\mathrm{}}\left(\frac{\mu c^2}{{10}^8 \mathrm{ev}}\right)$ sec.