Measurement of time resolution of the Mu2e LYSO calorimeter prototype

Abstract

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 $e^{-}$ 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 30x30x130 mm${}^3$, LYSO crystals read out by 10x10 mm${}^2$ Hamamatsu Avalanche Photodiodes (APDs). The energy dependence of the measured time resolution can be parametrized as $\ddot{I}{ƒ}_t(E)=a/\sqrt{E/\mathrm{GeV}}\oplus b$, with the stochastic and constant terms $a=(51\pm 1)$ ps and $b=(10\pm 4)$ ps, respectively. This corresponds to the time resolution of ($162\pm 4$) ps at 100 MeV.

18 pages, 14 figures, accepted for the journal Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment