Throughout all periods of data taking, the main goal of the NA48 experiment has been the search for CP violation (CPV) in kaon decays. The observable η +− links the parameters of indirect and direct CPV (η +− = ε + ε ) and is defined as the CP violating amplitude ratio of the neutral kaon decaying into two charged pions: η +− = A(K L → π + π − )/A(K S → π + π − ). NA48 has determined |η +− | via the measurement of the ratio of decay rates Γ(K L → π + π − )/Γ(K L → πeν), denoted as Γ K2π /Γ Ke3

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... using a pure K L beam in 1999. From a sample of 47000 K 2π and five million K e3 decays, we obtained results for Γ K2π /Γ Ke3 , BR(K L → π + π − ) and |η +− |. Complementary with ε /ε, the observable for direct CPV in the charged kaons sector is the asymmetry A g = (g + − g − )/(g + + g − ) of the linear slope parameter g in the Dalitz plot of K ± → 3π decays. The NA48/2 experiment used simultaneous K + /K − beams, and from the data samples taken in 2003 and 2004, 3 × 10 9 K ± → π ± π + π − and 9 × 10 7 K ± → π ± π 0 π 0 were selected. The charge asymmetry parameter A g was determined with a total uncertainty of ∼ 2 × 10 −4 for each mode, ten times more accurate than previous measurements. May 21-25, 2007 Laboratori Nazionali di Frascati dell'INFN * Speaker. † On behalf of the NA48 and NA48/2 collaborations: Cagliari, Kaon International Conference