Gamma Large Area Silicon Telescope (GLAST) applying silicon strip detector technology to the detection of gamma rays in space

Abstract

The recent discoveries and excitement generated by space satillite experiment EGRET (presently operating on the Compton Gamma Ray Observatory (CGRO)) have prompted an investigation into modern detector technologies for the next generation of space based gamma ray telescopes. The GLAST proposal is based on silicon strip detectors as the “technology of choice” for space application: no consumables, no gas volume, robust (versus fragile), long lived, and self-triggerable. The GLAST detector basically has two components: a tracking module preceding a calorimeter. The tracking module has planes of crossed strip (x, y) 300 μm pitch silicon detectors coupled to a thin radiator to measure the coordinates of converted electron-positron pairs. The gap between the layers (∼ 5 cm) provides a lever arm for track fitting resulting in an angular resolution of < 0.1° at high energy. The status of this R & D effort is discussed including details on triggering the instrument, the organization of the detector electronics and readout, and work on computer simulations to model this instrument.