Development of a novel HV-CMOS active pixel sensor AstroPix for gamma-ray space telescopes

AMEGO-X is one of the proposed MeV gamma-ray missions and its gamma-ray detector consists of silicon trackers and calorimeters. In order to efficiently detect MeV photons and to have precise Compton reconstruction, the silicon sensors must be fully depleted and have a good positional resolution (~500 um) with a good energy resolution. On top of that, the power consumption of the silicon detector must be low (< 1.5 mW/cm2). We have been developing AstroPix, an HV-CMOS active pixel sensor, to fulfill such requirements. Our latest AstroPix (ver.3) is the first full reticle chip designed to meet the requirements for both pixel pitches and power consumption. We report basic characterization of AstroPix-v3 such as I-V, noise, energy calibration/resolutions, dynamic range, and indirect depletion depth measurements using gamma-ray sources. We also present the status of a 2×2 array of AstroPix, Quad-chip, which is the smallest component of the silicon tracker.