Measurement of epsilon'/epsilon in the neutral Kaon system

A measurement of the ratio of the CP-nonconservation parameters, epsilon'/epsilon, in the K/sup 0/K /sup 0/ system was performed through a study of two-pion decays with and without a regenerator. To reduce systematic effects, K/sub L/ and K/sub S/ decays were recorded simultaneously with a double beam. Over 3100 K/sub L/..-->..2..pi../sup 0/ events were reconstructed leading to the result epsilon'/epsilon = -0.0046 +- 0.0053 +- 0.0024 (the first error is statistical, the second systematic). The measurement agrees with previous less precise determinations but, because of theoretical uncertainties, is not able to test decisively the Kobayashi-Maskawa mechanism.