Dual-readout calorimetry with crystals

Analysis of the signals generated by high-energy particles in lead tungstate crystals shows that a significant fraction (up to 20%) of the light generated in these crystals is not the result of scintillation processes, but rather of the Cherenkov mechanism. We have explored this phenomenon with the purpose to improve the characteristics of hadron calorimeters. A small electromagnetic calorimeter consisting of lead tungstate crystals was exposed to 50 GeV electrons and pions. This calorimeter was backed up by the DREAM Dual-Readout Calorimeter, which measures the scintillating and Cherenkov light produced in the shower development, using two different media. The signals from the crystal calorimeter were analyzed in great details in an attempt to determine the contributions from these two types of light to the signals, event by event. This information makes it possible to eliminate the dominating source of fluctuations and thus achieve an important improvement in hadronic calorimeter performance. Preliminary results on the dual-readout of a BGO crystals are also reported.