Measurement of time resolution of the Mu2e LYSO calorimeter prototype

In this paper we present the time resolution measurements of the Lutetium–Yttrium Oxyorthosilicate (LYSO) calorimeter prototype for the Mu2e experiment. The measurements have been performed using the e−e− beam of the Beam Test Facility (BTF) in Frascati, Italy in the energy range from 100 to 400 MeV. The calorimeter prototype consisted of twenty five 30×30×130mm3, LYSO crystals read out by 10×10mm2 Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as σt(E)=a/E/GeV⊕b, with the stochastic and constant terms a=(51±1)ps and b=(10±4)ps, respectively. This corresponds to the time resolution of (162±4)ps at 100 MeV.