The Large Area Telescope (LAT) on the Gamma-ray Large Area Space Telescope (GLAST)

The Gamma-ray Large Area Space Telescope, GLAST, is a low Earth orbit observatory which will study the cosmic gamma-ray sky in the energy range 20 MeV to >300 GeV, and detect gamma-ray bursts photons from 10 keV to 25 MeV. With its launch in 2007, GLAST will allow precision studies of high energy phenomena, including black holes and active galactic nuclei; gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilation, Lorentz invariance violation, and exotic relics from the Big Bang. The high-energy measurements are made by the Large Area Telescope (LAT), which consists of a pair conversion tracker, a hodoscopic crystal calorimeter, a segmented plastic scintillator anticoincidence shield, and a flexible trigger and onboard analysis system. The LAT design is described, along with the expected science performance based on detailed simulations of the instrument's response to expected sources and cosmic rays, including event reconstruction, and a multivariate classification method to improve resolution and distinguish signal and background.