Design and performance studies of the calorimeter system for an FCC-hh experiment

The study of physics reach and feasibility of the Future Circular Collider is on-going. The goal for the proton–proton collider (FCC-hh) is centre–of–mass collision energy of 100 TeV and integrated luminosity of 20 ab$^{-1}$, extending the research carried out at the current High Energy Physics facilities. Detectors for the FCC experiments need to be designed taking into account the difficult conditions, in particular the radiation load of the detector and the enormous number of the simultaneous collisions (in–time pile–up), expected to be reaching the level of 〈µ〉 = 1000. Additionally, the boost of the produced particles calls for a higher granularity of the detectors and higher energy of the produced particles requires thicker calorimeters to ensure shower containment. The baseline calorimetry system for an FCC experiment is presented. Liquid argon is used as an active material for the electromagnetic calorimetry, as well as for the hadronic calorimeters for |η| > 1.6. Plastic scintillator is used in the hadronic calorimeter in the central region. Presented single particle measurements meet the design energy resolution goal of $\frac {\sigma_E}{\langle E\rangle}$ $\leqslant$ $\frac {10\%}{\sqrt{E(GeV)}}$ $\oplus$ $0.7\%$ for photons and electrons and $\frac {\sigma_E}{\langle E\rangle}$ $\leqslant$ $\frac {50\%}{\sqrt{E(GeV)}}$ $\oplus$ $2.5\%$ for pions. An estimation of the effect of pile-up is presented, with the clear indication that pile–up mitigation is the main challenge of the FCC-hh collisions and is now the main focus of the detector design studies.