Search for CP-Violation in KS -> 3pi0 decays with the NA48 detector

The decay KS -> 3pi0 is forbidden by CP conservation. Using a sample of more than 6 million K -> 3pi0 decays, the NA48 Collaboration has improved the limit on eta_{000} = A(KS -> 3pi0)/A(KS -> 3pi0) and on the branching ratio Br(KS -> 3pi0) by about one order of magnitude. Using this result and the Bell-Steinberger relation, a new limit on the equality of the K0 and K0bar masses is obtained improving by about 40% the test of CPT conservation in the mixing of neutral kaons.