Construction and performances of an high granularity calorimeter

In this paper we describe the realization and performances of an high granularity calorimeter. The calorimeter is a spaghetti like calorimeter built with lead and scintillating fibers. The lead foils are 0.5 mm thick shaped with grooves to accommodate the scintillating fibers. A single prototype has been built. The read-out is through photomultipliers (pmts) located on both sides of the module with a 4.2x4.2 cm² granularity per single pmt. One side of the calorimeter has been equipped with the new R8900 Hamamatsu pmts with 16 anodes. On this side the light has been driven using mini light guides from the calorimeter surface to the multi anode surface. On the opposite side a read-out based on standard single anode pmts and light guides has been implemented. The signal from the pmts has been amplified and split. The split signal has been delivered to analog digital converters and to a discrimination system followed by the time to digital converters to record the time of the charge deposition. A dedicated electronic was also built to use the split signal in order to assert a trigger signal. In this paper we describe the calorimeter construction and show cosmic ray and test beam results.