Test beam results with LuAG fibers for next-generation calorimeters

For the next generation of calorimeters, designed to improve the energy resolution of hadrons and jet measurements, there is a need for highly granular detectors that require peculiar geometries. Inorganic scintillators can provide good stopping power to allow compact calorimeter designs together with an excellent energy resolution. The micropulling-down technique allows to grow crystal fibers with high aspect ratio providing good granularity. Designs based on dual-readout could also be considered since the host matrices of extrinsic scintillators behave as a Cherenkov radiator in the absence of the scintillating dopant. We report here about results obtained with crystal fibers of 22 cm length and 2 mm diameter of lutetium aluminium garnet (LuAG, Lu ₃Al₅O₁₂). The response of such fibers in a high energy physics environment has been investigated through a test beam campaign at the CERN PS facility using electrons in the 50-150 GeV energy range. The results, proving the potential of LuAG fibers for calorimetry applications, have been used to validate a Geant4 simulation which allowed to study different configuration of a fiber-based detector. Possible implementations of the crystal fibers technology into a real calorimeter are also discussed.