A-STEP for AstroPix: Development and Test of a space-based payload using novel pixelated silicon for gamma-ray measurement

Next-generation medium-energy gamma-ray instruments sensitive from 25 keV to 1 GeV must be able to measure and reconstruct incident photons in the photoabsorption, Compton, and pair-production regimes. Such robust functionality requires a tracker with high resolution, low noise, and low power. The monolithic CMOS active pixel silicon sensor AstroPix is a novel mission-enabling technology. AstroPix will provide the energy- and angular-resolution required of a medium-energy gamma-ray telescope while reducing noise with the dual detection-and-readout capabilities of an HVCMOS chip. Plans for A-STEP, a funded Astropix Sounding rocket Technology dEmonstration Payload, will be presented. This roughly 2U-sized payload will include three layers of AstroPix quad-chips for cosmic ray and gamma ray detection and tracking. This technology demonstration mission also strengthens the design readiness of AMEGO-X, an MIDEX-sized MeV telescope mission concept. Additional supplementary development and testing of the AstroPix project will also be considered, including A-STEP simulation efforts for environment and detector response modeling.