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We present γ-ray radiation detection in a neutron radiation environment using a monolithic active pixel sensor (MAPS) camera without conversion or shielding layers. The measured output signal is the sum of the pedestal value, noise, and real radiation response signal. The sensor response shows that the MAPS camera is sensitive to neutrons and can capture a single photon. The number of pixels with a signal exceeding 100 exhibits a strong dependence on the dose rate and is the best indicator of this value. Therefore, a MAPS camera can be efficiently used as a radiation detection sensor in a robotic system, further limiting human errors in performing radiation detection in complex nuclear radiation environments.

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Abstract:In this paper, we present the availability of an active pixel sensor (APS) with four transistors (4T) as a video monitor and radiation detector. Analyzing radiation damage must be one of the first steps in recovering from nuclear accidents, and the radiation response characteristic is the basis for the use of 4T-APS to detect radiation. The goal of this work is to suggest the use of cameras with 4T-APS in widely distributed irradiation detectors. The total ionizing dose (TID) of radiation damage on 4T-APS provided a threshold. Radiation tolerance was improved with the help of a radiation shielding structure. The radiation response showed integration time dependence and pixel information dependence, and greater radiation response was observed from the pixels with lower grayscale values. Two methods are suggested based on different monitoring scenes. This study can help to greatly improve nuclear accident emergency response and the safety of nuclear facilities.

In this paper, we discuss the potential use of four transistor active pixel sensor (4T-APS) as a video monitor at a nuclear accident site with a high level of γ radiation. The resistance and radiation responses to γ radiation were investigated by radiation experiments using 137Cs and 60Co γ-ray sources. The radiation resistance of 4T-APS was studied by testing the mean and the maximum dark current of the sensors after irradiation. A random spatial distribution of radiation response events was observed upon analyzing these events on the video images in a given time during irradiation. The background dependence of the 4T-APS was also studied by comparing the grayscale incremental value of the images with different color and grayscale backgrounds: the radiation response events were obvious on the images with a background having a smaller grayscale value or a deeper color. Finally, the color saturation and resolution of the images were tested using a vector oscilloscope and a test card. When the total ionizing dose was less than or equal to the damage threshold, no significant performance deterioration of 4T-APS was observed in an environment with sufficient light.