Comparison of high-energy electromagnetic shower profiles measured with scintillation and Cherenkov light

Results are presented of detailed measurements of high-energy electromagnetic shower profiles measured in a copper-based fiber calorimeter. The calorimeter was equipped with a mixture of scintillating fibers and undoped (quartz or clear plastic) fibers. The latter measured Cherenkov light generated in the shower development process, whereas the scintillating fibers measured the energy deposit profile. Both lateral and longitudinal profiles were measured for electrons in the energy range 8-200 GeV. The scintillator and Cherenkov profiles exhibit some very striking differences, which are discussed and compared with results of Monte Carlo simulations.