In the realm of high-energy physics, a team of researchers from various institutions, including CERN and the University of Turin, has been exploring the potential of Monolithic Active Pixel Sensors (MAPS) in advanced CMOS imaging technologies. These sensors are crucial for next-generation tracking systems, where radiation hardness and precise vertex reconstruction are paramount.
The researchers, led by Gianluca Aglieri Rinella and Luca Aglietta, evaluated the performance of Analog Pixel Test Structures (APTS) fabricated in the TPSCo 65 nm CMOS imaging process. The prototypes featured 10 um pitch pixels with a fast operational amplifier-based buffering stage, enabling direct characterization of intrinsic sensor response. The study, published in the Journal of Instrumentation, assessed the timing and charge collection of DC- and AC-coupled designs, including devices exposed to significant levels of non-ionizing energy loss.
The DC-coupled sensors demonstrated stable performance, maintaining a time resolution of less than 70 ps and a detection efficiency of over 99% up to a non-ionizing energy loss (NIEL) of 10^15. This indicates their robustness and reliability in high-radiation environments, which is crucial for applications in the energy sector such as nuclear power plants and radiation monitoring systems.
AC-coupled sensors, on the other hand, showed a wide operational margin with efficiencies above 99% for clusterization thresholds below 150 electrons. Although AC coupling allows for higher reverse bias than DC-coupled sensors, the reduced signal amplitude lowers the signal-to-noise ratio, increasing the jitter contribution. However, at high reverse bias, AC-coupled sensors achieved time resolutions comparable to DC-coupled versions, demonstrating the viability of both approaches.
The researchers suggest that combining the low capacitance of DC-coupled designs with the high-bias capability of AC coupling could further enhance time resolution. This could lead to more precise and efficient tracking systems, benefiting various sectors, including medical imaging, industrial inspection, and security screening.
In conclusion, the study confirms the suitability of 65 nm MAPS for future collider detectors requiring high radiation tolerance, efficiency, and timing precision. The findings could pave the way for advancements in radiation detection and measurement technologies, with practical applications in the energy industry and beyond.
This article is based on research available at arXiv.