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Particle beam tests for the GLAST-LAT Calibration
DRAFT
Speaker : TBD - suggested for a talkTBD on behalf of the Beam Test Team (oral)
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
DRAFT
Speaker : TBD - suggested for a posterTBD on behalf of the Beam Test Team (poster)
The main sources of background for the operation of the GLAST-Large Area Telescope are primary protons, albedo gammas from the earth and photons coming from interaction of positron and protons in the micro-meteoride-shield (MMS) surrounding the LAT, which create photon pairs through annihilation and pi0 decay.
An extensive beam test campaign was performed in summer 2006 on the LAT Calibration Unit (CU), a detector built with flight spare parts of the LAT; the goal of the program was to support the LAT Instrument Calibration by providing direct measurements of the physical processes taking place in the CU detector when exposed to different beams, by comparing the obtained measurements with Monte Carlo predictions and by eventually validating the full LAT MC code used to provide instrument calibrations and background rejection strategies.
The study of the signal produced in the CU by sources of the LAT background was performed with photon beams shot from the side of the CU, proton beams and positrons beams reaching the CU after crossing an MMS target.
Results from analysis of these data are presented in this talk.