Measuring the PSF and the energy resolution with the GLAST-LAT Calibration Unit
ACCEPTED as P3.4 Philippe Bruel (oral)
Because of the large phase space of the LAT and its complex structure, an advanced MonteCarlo simulation of the LAT, based on the Geant4 package, is used to optimize the instrument response functions and the background rejection. Testing the instrument with real beams at accelerator facilities was needed to make sure that this simulation is able to reproduce real data.
Between July and September 2006, we have tested the LAT Calibration Unit (CU) at CERN, both at PS and SPS accelerators. The CU is a detector built with two complete flight spare modules, a third spare calorimeter module, five anticoincidence tiles located around the telescope and flight-like readout electronics. The CU was exposed to gamma beams (from ~50 MeV up to 2.5 GeV) and electron beams (from 2 GeV up to 280 GeV) in many configurations (various incoming angles and impact points) in order to cover the large phase space of the LAT.
This large amount of data will allow us to determine the performances of the LAT, such as PSF and energy resolution. This poster will present the preliminary results on these topics.