Advancements in Gamma-ray Sensor Technology for Future Space Telescopes

AstroPix is a new type of monolithic high-voltage CMOS active pixel sensor designed for use in next-generation medium-energy gamma-ray observatories, such as the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X). The sensor aims to operate with a power consumption of less than 1.5 mW/cm² while supporting a pixel pitch of up to 500 µm. The latest versions, AstroPix2 and AstroPix3, have been developed, with AstroPix2 consuming 3.4 mW/cm² and AstroPix3 consuming 4.1 mW/cm². AstroPix2 features a pixel pitch of 250 µm, while AstroPix3 meets the target specifications for AMEGO-X with a pixel pitch of 500 µm.

Performance evaluations revealed that a single pixel in the AstroPix2 chip has a dynamic range from 13.9 keV to 59.5 keV, achieving an energy resolution that meets the AMEGO-X target of less than 10% (FWHM) at 60 keV. For AstroPix3, energy calibration across most pixels yielded a mean energy resolution of 6.2 keV (FWHM) at 59.5 keV, with 44.4% of the pixels meeting the target value. The dynamic range for AstroPix3 spans from 22.2 keV to 122.1 keV.

Additionally, radiation tolerance testing was conducted on AstroPix. An AstroPix2 chip was exposed to approximately 10 Gy from a high-intensity 60Co source, remaining fully operational post-irradiation, albeit with a 4% decrease in gain. These findings indicate that AstroPix sensors could significantly enhance the capabilities of future gamma-ray observatories, improving the detection and analysis of cosmic phenomena.

For more detailed information, the full paper titled "Performance evaluation of the high-voltage CMOS active pixel sensor AstroPix for gamma-ray space telescopes" can be accessed here.