Performance of the GLAST/LAT for the Observation of GRB Spectra

GLAST is a gamma-ray mission which will be launched in autumn 2007. It is equipped with the GLAST Burst Monitor (GBM) which detects GRBs with high reliability and provides a position and energy spectrum in the range between 10 keV and 25 MeV. The Large Area Telescope (LAT) will observe photons with energies from 20 MeV up to more than 300 GeV.Here we present a systematic study of the performance of the LAT for the reconstruction of the energy spectrum of Gamma-Ray Bursts (GRBs), based on the simulation of 1 year of data taking. We focus on deviations from a pure power-law photon spectrum (exponential cut-offs). This feature can provide insight in the particle acceleration mechanisms at work in GRBs; and it can be used to probe the Extra-Galactic Background Light