PERFORMANCE THE GLAST-LAT: BEAM TEST RESULTS

Between July and November 2006, the LAT Collaboration has performed a massive campaign of particle beam test on a Calibration Unit (CU), in order to study the performance of the LAT and validate the LAT Geant4 based simulation. We have tested the LAT Calibration Unit at CERN, both at PS and SPS accelerators, and at GSI. The Calibration Unit is a detector built with two complete flight spare modules, a third spare calorimeter module, five antocoincidence tiles located around the telescope and flight-like readout electronics. The LAT response to minimum ionizing particles, high energy electrons, gamma ray and ions (C,Xe) in a wide energy range, has been studied. This large amount of data allowed to determine the LAT performance, such as the capability to reconstruct the direction of the incident gamma-rays.