A Water Cherenkov Spectrometer

A water Cherenkov spectrometer with a thickness of 0.5X0 has been calibrated on the secondary electron beam at the Pakhra accelerator of the Lebedev Physical Institute of the Russian Academy of Sciences. The amplitude and time recording systems of the spectrometer are based on FEU-85 photomultiplier tubes. It has been determined that the relative energy resolution is not high in the electron energy range of 10–30 MeV and is minimal, ~50%, at electron energy E ~ 25 MeV. Three regions are discerned in the dependence of the time-resolved spectrum of the middle channel on the electron energy: the dependence is proportional at 0 < E < 13 MeV and nonlinear at 13 < E < 45 MeV. At E ≥ 45 MeV, the value of the middle-channel timing spectrum is independent of the energy.