Test of a scintillating-fiber calorimeter for photons with energies below 1 GeV

An array consisting of scintillating fibers embedded in a lead matrix was tested for use as a calorimeter for showers induced by energetic photons (50 MeV≤Eγ<1 GeV). Experimentally, its efficiency was found to equal 100% for photon energies in excess of 100 MeV, the energy resolution is (σ/E)∼10%/(Eγ/GeV)-1/2 over the full energy range. Extensive Monte Carlo studies show that the efficiency drops rapidly around Eγ=40 MeV. The suitability of cosmic radiation for calibration purposes is demonstrated. Based on these studies design criteria for future arrays can be matched to experimental requirements. (orig.)