Gamma-ray imaging by silicon detectors in space: Presentation of the AGILE reconstruction method and kalman filter algorithms

We present the AGILE REconstruction Method (AREM) and the track finding optimization by Kalman filter algorithms. AREM is a method of γ-ray direction reconstruction to be applied to high-resolution Silicon Tracker detectors in space. It can be used in a “fast mode,” independently on Kalman filters techniques, or in an “optimized mode,” including Kalman filter algorithms for track identification. AREM correctly addresses three points of the analysis which become relevant for off-axis incidence angles: 1) intrinsic ambiguity in the identification of the
tracks and conversion plane; 2) proper identification of the 3-D reconstructed direction; 3) careful choice of an energy weighting scheme for the 3-D tracks. We present the preliminary results of the angular resolution obtained by analyzing simulated γ-rays in the AGILE detector. The excellent spatial resolution obtained by the AGILE Silicon Tracker allows to improve the angular resolution by a factor ∼2 at energies ≳ 400 MeV with respect to previous spark chamber detectors (e.g., EGRET).