A-STEP: the AstroPix sounding rocket technology demonstration payload

A next-generation medium-energy (100 keV to 100 MeV) gamma-ray observatory will greatly enhance the identification and characterization of multi-messenger sources. Coupling gamma-ray spectroscopy, imaging, and polarization to neutrino and gravitational wave detections will develop our understanding of various astrophysical phenomena including compact object mergers, supernovae remnants, active galactic nuclei and gamma-ray bursts. AstroPix is a monolithic HV-CMOS active pixel sensor which enables future gamma-ray telescopes in this energy range. AstroPix is capable of low-power (< 1.5 mW/cm^2), high spatial (500 um x 500 um) and spectral (< 10% FWHM at 122 keV) tracking of photon and charged particle interactions for Compton and pair-production imaging. A prototype multi-layered AstroPix instrument, called the AstroPix Sounding Rocket Technology Demonstration Payload (A-STEP) will be the first demonstration of AstroPix’s operation in a near-space environment. In this presentation we overview the design and state of development of the first AstroPix multi-layer payload.