Speaker
Description
Highly granular calorimeters with a fast response and a large dynamic range are at the core of most detector concepts currently proposed at the next-generation colliders, where the implementation of particle flow algorithms would have a significant impact on the physics performance. Optical sampling calorimeters may be particularly suited for this doctrine, as they combine excellent resolution and timing performance, a great flexibility in segmentation and scaling, and relatively simple construction and maintenance.
Indeed, a sampling hadronic calorimeter (HCAL) based on plastic scintillating tiles is currently being developed for the ALLEGRO (A Lepton coLlider Experiment with Granular calorimetry ReadOut) experimental apparatus proposed at the FCC-ee: radially oriented scintillating plastic tiles are inserted in a stainless steel frame and coupled to one WLS fibre each, to route the light output onto silicon photomultipliers housed in dedicated drawers in the outer volume of the detector. This configuration allows for a limited reduction of the active volume and for an easy access to the photodetection system and to the frontend electronics. In the current design, each tile would be read out individually, which results in about one million cells and an excellent granularity.
In the last couple years, significant advancements were achieved in different areas of both the development of the first large-scale prototypes, currently under construction, and of the full-scale design - mechanics, optics, electronics, calibration systems. Moreover, the calorimetric performance is being studied with the ALLEGRO full-simulation framework. All these aspects will be discussed. In May 2026, the first beamtest of the ALLEGRO HCAL took place at the CERN East Hall. Preliminary results of the data taking session will be presented.