Precise Measurement of theK+Lifetime

A measurement of the $K^{+}$ mean lifetime has been made to resolve the discrepancy of 4.5 standard deviations between the two previous best measurements. An accurate timing system was used, enabling a precision of nearly 1 part in 1000 to be obtained The result was a mean lifetime of 12.380±0.016 nsec. The time spectrum over six mean lifetimes showed no deviations from a pure exponential at a 0.1% level.