The complex quantity X = (amplitude of the ΔS = -ΔQ processK-o → π-e+v/amplitude of the ΔS = +ΔQ process Ko → π-e+v) has beenmeasured in a counter-spark-chamber experiment at the LRL Bevatron.Assuming CPT invariance, ImX ≠ 0 implies CP-violation in the decay.Ko - mesons were produced in two brass targets by 2.85 GeV/c pions.A series of veto counters and hodoscopes selected neutral decays intotwo charged particles. The electron and pion were identified by (1)pulse height in a Freon 12 threshold Cerenkov counter, (2) visualappearance in three radiation lengths of lead, and (3) pulse heightin a set of fourteen shower counters. From 240K pictures, 1,079events were isolated with a (2 ± 1)% background level. A maximumlikelihood fit to the π-e+ and +e- time distributions gave the result:
ReX = -.069 ± .036
ImX = +.108 ± +.092-.074
This result is within two standard deviations of X = 0 and thereforeconsistent with it (relative probability = 0.25). It is, on the otherhand, more than four standard deviations from the existing worldaverage (+0.14, -0.13) and therefore inconsistent with it (relativeprobability < 3.3 x 10-4). Sensitivity of the result to a largenumber of possible systematic effects was investigated and it wasconcluded that any systematic error was small compared to thestatistical error.
