Test beam studies of silicon timing for use in calorimetry

The high luminosityupgrade of the Large Hadron Collider(HL-LHC) at CERN is expected to provide instantaneous luminositiesof 5×10^(34) cm^(−2) s^(−1). The high luminositiesexpected at the HL-LHC will be accompanied by a factor of 5–10 more pileup compared with LHC conditions in 2015, further increasing the challenge for particle identificationand event reconstruction. Precision timing allows us to extend calorimetric measurements into such a high density environment by subtracting the energy deposits from pileup interactions. Calorimeters employing silicon as the active component have recently become a viable choice for the HL-LHC and future collider experiments which face very high radiation environments. In this paper, we present studies of basic calorimetric and precision timing measurements using a prototype composed of tungsten absorber and silicon sensor as the active medium. We show that for the bulk of electromagnetic showers induced by electrons in the range of 20–30 GeV, we can achieve time resolutions better than 25 ps per single pad sensor.