Characterization of a CZT-based spectrometer for underwater operation via simulations and experiments

The harsh environmental conditions in the marine environment pose various constraints on developing efficient instruments to carry out long-term, in situ radioactivity measurements. In addition, the strong attenuation of γ-rays in the water medium, makes remote sensing of such radiation a challenging task. In the present work, we report on the efforts to find the optimal characteristics and deployment scenarios of a new prototype γ-ray instrument based on a small-size CZT crystal enclosed in seal-tight housing to be deployed for operation in large depths. Lab experiments and detailed Monte Carlo simulations were combined to validate the actual crystal dimensions, determine its efficiency and energy resolution, as well as establish the minimum detectable activity values of the instrument in different configurations and scenarios.