Time resolution improvement of the electromagnetic calorimeter PHOS (CERN/ALICE experiment) is discussed. The existing channel consists of a scintillating crystal of PbWO4 viewed by APD (avalanche photo diode) HAMAMATSU S8664-55(S8148) coupled to the low noise charge sensitive preamplifier. For improvement of the timing resolution of the detecting channel it is proposed to enter one more photodetector SiPM (the silicon photo multiplier) in addition to the existing APD photodetector. APD signal is used for energy measurements and SiPM provides timing information. Laboratory tests and beam-test results are presented. We discuss energy and time resolutions of detecting channel with two very different photodetectors.

NRC “Kurchatov Institute” and MEPhi