LuAG material for dual readout calorimetry at future high energy physics accelerators

One of the main challenges for detectors at future high energy collider experiments is high precision measurement of hadrons and jet energy and momentum. One possibility to enable such measurement is the particle flow approach (PFA) that requires a complex highly segmented calorimeter system to identify and to track all particles in a jet. An alternative so-called dual readout approach consists of simultaneously recording, in an active medium, scintillation light that is proportional to total energy deposit and Cerenkov light that is proportional to the electromagnetic part only, thus allowing extracting the electromagnetic fraction of the total shower energy on an event by event basis. A promising candidate to be used for dual readout calorimeter is Lutetium Aluminium Garnet Lu₃Al₅O₁₂ (LuAG). Its high density, relatively short radiation length and interaction length provide sufficient stopping power necessary for hadronic calorimetry at high energy colliders, the fundamental absorption edge at 177 nm combined with a very large optical transmittance window and a high refraction index (n = 1.84) make LuAG an excellent Cerenkov radiator. Moreover cerium doped LuAG (LuAG:Ce³⁺) has good scintillating performances in terms of light yield and decay time due to the efficient radiative recombination 5d-4f from Ce3+ ion. LuAG can be produced either in bulk crystal or as fiber crystal allowing to assess its performance in two different approaches for dual readout calorimetry. As bulk crystals Cerium doped LuAG can be used in the method based on the separation of scintillation and Cerenkov signal produced in homogeneous detector blocks. In form of fibers it can be used in the method using so-called meta-crystals consisting of both Ce doped and undoped LuAG crystal fibers. The undoped fibers behave as Cerenkov radiator while Ce-doped fibers behave as scintillators. This talk reviews the properties of LuAG material in view of its use a- - s scintillator both for bulk and fiber scintillators.