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The calibration strategy of the GLAST Large Area Telescope combines analysis of cosmic ray data with accelerator particle beams measurements. An advanced MonteCarlo simulation of the LAT, based on the Geant4 package, was setup to reproduce the LAT response to such radiation, benchmark its performance throughout its entire operation and refine background rejection strategies.
To validate the LAT simulation, a massive campaign of particle beam tests was performed between July and November 2006, in parallel with the LAT integration and test, on the LAT Calibration Unit (CU). This 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 CU was exposed to a large variety of beams, representing the whole spectrum of the signal that will be detected by the LAT, using the CERN and the GSI accelerator facilities. Beams of photons (0-2.5GeV), electrons (2-300GeV), hadrons (pions and protons, ~GeV-100GeV) and ions (C, Xe, 1.5GeV/n) were shot through the CU to measure the physical processes taking place in the detector and eventually fine-tune their description in the LAT MonteCarlo simulation.
This talk describes the motivations and goals of the test runs, the many different experimental setup used to select the required particles and trigger the CU, the measured performance of the CU and the first results of the LAT MonteCarlo validation.
Response of the GLAST-LAT Calibration Unit to sources of background : Background Poster Page
SUBMITTED Speaker TBD on behalf of the Beam Test Team (poster)
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