Fig. 1

Time variation of meson signal from an annihilation experiment. D(0) on laser target, 50 mbar D2 gas in 2 m long tubular vertical chamber. The decay time is obtained by a converged non-linear least squares 2-parameter fit in the program SigmaPlot 14 using 560 measured points for the fit. The time constant value found agrees within 0.4% with the accepted decay time for a stationary charged pion, at 26.033 ns [22]