Calculation of detection efficiency of the fiber-optic sensor to measure radioactive contamination using MCNP simulation

In this paper, a fiber-optic radiation sensor (FORS) was developed to measure gamma rays from the radionuclides frequently found in radioactively contaminated soil. The sensing probe of the FORS was made of an inorganic (Lu,Y) 2 SiO 5 :Ce (LYSO:Ce) scintillator, a mixture of epoxy resin and hardener and a plastic fiber. The FORS was applied to measure gamma rays from Cs-137 source (1.1 μCi) in a disk shape. Also, MCNP simulation was performed for the same geometry as that in the experimental setup. Comparison between measurements by the FORS and MCNP simulation showed that the detection efficiency of the fiber-optic sensor was about 19.2%. The FORS is expected to be useful in measuring gamma rays from the radioactive soil at nuclear facility site.