Electromagnetic calorimeter for the HADES@FAIR experiment

An electromagnetic calorimeter (ECAL) is being developed to complement the dilepton spectrometer HADES currently operating on the beam of the SIS18 heavy-ion synchrotron at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. The ECAL will allow the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions in the energy range of 2–10 AGeV with the beam of the future accelerator SIS100@FAIR. The calorimeter will also improve the electron-hadron separation of the spectrometer, and will be used for the detection of photons from strange resonances in elementary and heavy ion reactions as well. The calorimeter will consist of 978 modules divided into 6 sectors, and it will cover forward angles of $16^{\circ} < \Theta < 45^{\circ}$ and almost full azimuthal angle. Each module consists of a lead glass Cherenkov counter, photomultiplier, HV divider and an optical fiber. A dedicated LED based system being developed to monitor the stability of the calorimeter is discussed. Various prototypes of front-end electronics are presented and the achieved energy and time resolution determined using pulses from a pulse generator and a real detector signal induced by LED pulses and cosmic muons is shown as well