Recent results on dual readout in calorimetry from the DREAM Collaboration

The energy resolution of the hadronic calorimeters is mostly limited by the fluctuation of the electromagnetic component in the development of the shower. The dual readout technique proposed by DREAM aims to correct event by event for this fluctuation measuring at the same time scintillation and Cherenkov light. In the last years the DREAM Collaboration has performed several tests to exploit the dual readout technique in calorimeters. Many types of crystals (PbWO, BGO, BSO, etc.) have been exposed in test beams to evaluate the Cherenkov yield and how to optimize the light collection. The extention of the dual readout to crystals is in fact very important when an electromagnetic calorimeter composed by crystals is followed by an hadronic calorimeter. The possibility to use tiles of absorber interleaved with tiles of quartz and scintillator for the dual readout has also been considered. At present the DREAM Collaboration is testing new calorimeters with scintillating and clear fibers.