Development of AstroPix HV-CMOS Active Pixel Sensors for Future Gamma-Ray Space Telescope

Le résumé fourni par la source

All-sky medium-energy gamma-ray observations are essential to deepen our understanding of physics in high energy astronomical phenomena, and to further develop multi-messenger astronomy. Future all-sky MeV gamma-ray telescopes must have a large area detector and keep high sensitivities even in the energies in which Compton scattering is dominant. 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 ($500~\rm{\mu m}$) and have a good positional resolution ($\sim 500~\rm{\mu m}$) with a good energy resolution ($< 10$\% at 122 keV). On top of that, the power consumption of the silicon detector must be low ($< 1.5~\rm{mW/cm}^2$) given the required silicon area in the gamma-ray detector is huge ($24 \rm{m}^2$). We have been developing AstroPix, a high-voltage CMOS active pixel sensor, to fulfill such requirements. Our latest iteration of AstroPix, AstroPix4 is a $1\times1~\rm{cm}^2$ chip whose pixel pitches are $500 \times 500~\rm{\mu m}^2$ and its power consumption is about $2~\rm{mW/cm}^2$. In this contribution, we report an overview of our AstroPix development, basic characterization of AstroPix4, such as I-V measurement, noise characterization, energy calibration/resolutions, dynamic range, and indirect depletion depth measurements using gamma-ray sources. We will discribe the design of the next iteration of AstroPix. We also present the status of a $2\times2$ array of AstroPix, Quad-chip, which is the smallest component of the AMEGO-X's silicon tracker.

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