Abstract
The RADiCAL Collaboration is conducting R&D on precision-timing electromagnetic (EM) calorimetry to address the challenges expected in future collider experiments under conditions of high luminosity and/or high irradiation such as those expected at the FCC-ee and FCC-hh colliding beam facilities. Under development are sampling calorimeter structures known as RADiCAL modules, based on scintillation and wavelength-shifting (WLS) technologies, and read out by SiPM photosensors. The module in the test described here consists of alternating layers of very dense tungsten (W) absorber and scintillating crystal (LYSO:Ce) plates, assembled to a depth of 25 radiation lengths (X0). The scintillation signals produced by the EM showers in the region of EM shower maximum (shower max) are transmitted to SiPM located at the upstream and downstream ends of the module via quartz capillaries which penetrate the full length of the module and which contain either organic DSB1 WLS filaments or ceramic LuAG:Ce WLS filaments positioned within the region of shower max, where the shower energy deposition is greatest. The remaining volume within the capillaries, upstream and downstream of the WLS filaments, is filled and fused with quartz rod to form solid quartz waveguides. Preliminary results are presented of the timing resolution of the RADiCAL module over the energy range 25 GeV ≤ E ≤ 150 GeV using both types of wavelength shifters. The studies were conducted using electron beam in the H2 beamline at CERN, Geneva, Switzerland.