GAGG-based gamma-ray detector for in-situ ocean radiation monitoring

Abstract

Frequent monitoring of ocean radiation level in desired sites is required to manage the safety of nuclear power plant operation and rapidly deal with radiation discharge into the ocean. A typical method to measure ocean radiation is to analyze the sampled sea water or sediments in the laboratory [1-2]. However, this method is slow, bulky, and only applicable to restricted ocean sites. We are developing a novel in-situ ocean radiation monitoring system that features real-time detection of ocean radiation level based on remote ultra-high frequency communication. For gamma-ray detection, we selected Gadolinium Aluminum Gallium Garnet (GAGG) crystal because GAGG features excellent energy resolution, non-hygroscopic property, and no intrinsic activity [3]. Considering the challenge in gamma-ray detection efficiency due to substantial attenuation by water, a large-sized GAGG crystal was used. We first calibrated the gamma-ray detector consisted of GAGG crystal and silicon multiplier (SiPM). After the calibration, we conducted a water tank experiment of the system to evaluate the feasibility of the detector for ocean radiation monitoring system, targeting Cs-137 detection.