Calibration of AGILE-GRID with on-ground data and Monte Carlo simulations

TL;DR

This paper details the calibration of the AGILE-GRID instrument using ground-based gamma-ray beam tests and validates the Monte Carlo simulation, ensuring accurate performance predictions for space operations.

Contribution

It presents the first on-ground calibration of AGILE-GRID with a tagged gamma-ray beam and validates the Monte Carlo simulation against experimental data.

Findings

Good agreement between beam data and Monte Carlo simulation for angular resolution.

Validated simulation can reliably predict in-orbit performance.

Calibration enhances confidence in gamma-ray measurements from space.

Abstract

AGILE is a mission of the Italian Space Agency (ASI) Scientific Program dedicated to gamma-ray astrophysics, operating in a low Earth orbit since April 23, 2007. It is designed to be a very light and compact instrument, capable of simultaneously detecting and imaging photons in the 18 keV to 60 keV X-ray energy band and in the 30 MeV{50 GeV gamma-ray energy with a good angular resolution (< 1 deg at 1 GeV). The core of the instrument is the Silicon Tracker complemented with a CsI calorimeter and a AntiCoincidence system forming the Gamma Ray Imaging Detector (GRID). Before launch, the GRID needed on-ground calibration with a tagged gamma-ray beam to estimate its performance and validate the Monte Carlo simulation. The GRID was calibrated using a tagged gamma-ray beam with energy up to 500 MeV at the Beam Test Facilities at the INFN Laboratori Nazionali di Frascati. These data are used to validate a GEANT3 based simulation by comparing the data and the Monte Carlo simulation by measuring the angular and energy resolutions. The GRID angular and energy resolutions obtained using the beam agree well with the Monte Carlo simulation. Therefore the simulation can be used to simulate the same performance on-light with high reliability.