We propose a novel method to effectively observe the core region of ultra-high energy cosmic
ray (UHECR) air showers. The measurement of the core region has been challenging due to
saturation problems of surface detectors caused by the high particle density. However, simulations have shown the importance of collecting data from the core region for understanding UHECRs. To address this challenge, we propose to use compact and thin sensors, such as the CMOS camera image sensors commonly found in consumer devices. These sensors have the unique ability to accurately detect not only optical photons but also charged particles such as cosmic rays and environmental radiation. Due to their thinness, these CMOS have very small energy deposits, allowing high-density regions to be observed without causing saturation problems. In this study, we aim to construct a new observation model using small and thin sensors such as CMOS sensors and discuss the possibility of establishing a large-scale and cost-effective observation network for UHECRs through a simplified model. Our other related paper will further discuss the effective
use of CMOS sensors for cosmic ray observations.