Precision timing Calorimetry

a b s t r a c t Particle colliders operating at high luminosities present challenging environments for high energy physics event reconstruction and analysis. We discuss how timing information, with a precision on the order of 10 ps, can aid in the reconstruction of physics events under such conditions. We present calorimeter based timing measurements from test beam experiments in which we explore the ultimate timing precision achievable for high energy photons or electrons of 10 GeV and above. Using a prototype calorimeter consisting of a 1.71.71.7 cm3 lutetium–yttrium oxyortho-silicate (LYSO) crystal cube, read out by micro-channel plate photomultipliers, we demonstrate a time resolution of 33.572.1 ps for an incoming beam energy of 32 GeV. In a second measurement, using a 2.52.520 cm3 LYSO crystal placed perpendicularly to the electron beam, we achieve a time resolution of 59711 ps using a beam energy of 4 GeV. We also present timing measurements made using a shashlik-style calorimeter cell made of LYSO and tungsten plates, and demonstrate that the apparatus achieves a time resolution of 5475 ps for an incoming beam energy of 32 GeV. & 2014 Elsevier B.V. All rights reserved. 1