On-ground calibration of AGILE-GRID with a photon beam: results and lessons for the future
P. W. Cattaneo ; A. Rappoldi ; A. Argan ; P. Giommi; L. Salotti;
Jul - 2012
DOI: 10.1117/12.926445

Event Title : Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Published in: Proc. SPIE 8443
Publisher: SPIE
type: Conference Proceedings

At the core of the AGILE scientific instrument, designed to operate on a satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs an on-ground calibration with a γ-ray beam to validate the simulation used to calculate the energy response function and the effective area versus the energy and the direction of the γ rays. A tagged γ-ray beam line was designed at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali of Frascati (LNF), based on an electron beam generating γ rays through bremsstrahlung in a position-sensitive target. The γ-ray energy is deduced by the difference with the post-bremsstrahlung electron energy1-.2 The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). The use of the combined BTF-PTS system as tagged photon beam requires understanding the efficiency of γ-ray tagging, the probability of fake tagging, the energy resolution and the relation of the PTS hit position versus the γ-ray energy. This paper describes this study comparing data taken during the AGILE calibration occurred in 2005 with simulation.

keywords : Calibration ; Photons ; Gamma radiation ; Electrons ; Simulations ; Spectrometers ; Electron beams ; Scintillators ; Sensors ; Silicon