Feasibility of underwater radiation detector using a silicon photomultiplier (SiPM)

In this paper, the development of an underwater radiation detector is presented using a silicon photomultiplier (SiPM), CsI(Tl) scintillator, and light guide. The detector characteristics were evaluated. The detector has good energy resolution characteristics in which the gammaray emission energy 122 keV of Co-57 had an energy resolution of 18.12%, 356 keV of the Ba-133 spectrum had 10.91%, 662 keV of the Cs-137 spectrum had 8.84%, and 1332 keV of the of the Co-60 spectrum had 4.55%. Further, in the case of mixed sources, the gamma radiation peaks were readily distinguishable, and the R-squared value in the gamma-ray energy of 122-1332 keV for energy linearity was calculated to be 0.99937, demonstrating an exceptional energy linearity. In addition, radiative contaminated water was prepared as a liquid radiation source and characterized. The measurement results showed 0.61 +/- 0.0046 cps in the background and 0.74 +/- 0.0070 cps at the minimum concentration of 38.71 Bq/L. The R-squared value for concentrations in the range of 38.71-4955 Bq/L, which indicates the linearity of a detector based on the signal intensity, was determined to be 0.99710, indicating a good linear responsivity. The characterization results suggest that the radiation detectors based on SiPM- and CsI(Tl) can replace the currently used PMT-based radiation detector in an underwater environment.