Variation of the Rate of Decay of Mesotrons with Momentum
In order to determine the dependence of the probability of decay on momentum, mesotrons with range between 196 and 311 g/cm' of lead and mesotrons with range larger than 311 g/cm' of lead were investigated separately. The softer group of mesotrons was found to disintegrate at a rate about three times faster than the more penetrating group, in agreement with the theoretical predictions based on the relativity change in rate of a moving clock. A new value of the proper lifetime of mesotrons of (2.4+0.3) &(10 ' sec. is determined, based upon measurements with particles with momentum of approximately 5 &&10' ev/c.