LCcal: a calorimeter prototype for future linear colliders

We have constructed a prototype of an electromagnetic calorimeter, for future linear collider experiments, alternating 45 layers of lead and scintillator planes. The scintillation light is collected by means of WLS fibers from square cells of 5×5 cm². To improve the reconstruction of the shower profile, three silicon pad (∼0.9×0.9 cm²) detector planes have been inserted between the lead and scintillator layers at 2.6 and 12 X₀. The prototype has been tested with electron beams at low (50÷750 MeV) and high energies (5÷50 GeV): a good linearity in response and an energy resolution of ∼11.5%/√(E/GeV) have been achieved. A position resolution of 2.5 mm has also been measured for 10 GeV impinging electrons. The calorimeter particle identification capability has been tested comparing electron and pion beams.