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

Results are presented of measurements of high-energy hadronic shower profiles with a copper-based fiber calorimeter. This calorimeter was equipped with a mixture of scintillating fibers and undoped (quartz or plastic) fibers. The latter measured the spatial distribution of shower particles with velocities above the Cherenkov threshold, whereas the scintillating fibers measured the distribution of the deposited energy. Both the lateral and longitudinal characteristics of these profiles were measured for pions, with energies ranging from 20 to 300 GeV. The scintillator and Cherenkov profiles exhibit some striking differences, which are discussed and compared with results of Monte Carlo simulations.