A time-dependent angular analysis of decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of collected during Run 1 of the LHC. The CP -violating phase and decay-width difference of the d470949a8a4a9690fd9c70b4"> system are measured to be and , respectively, where the first uncertainty is statistical and the second systematic. This is the first time that ϕs and ΔΓs have been measured in a decay containing the ψ(2S) resonance.