## 3 Results and Discussion  
The transparency of the plastic scintillator decreases due to the coagulation of nanomaterials with high surface energy and precipitation during the plastic polymerization process, which may adversely affect the optical properties. Therefore, for the transparency of the plastic scintillator, it is necessary to be careful in the processes of stirring, bubbles removal, slow heating, slow cooling, and polishing. Figure 6a shows the transparency of the CdTe-loaded plastic, and Figure 6b,c show the UV-Vis absorption and PL emission spectra of the plastic scintillator. The absorption peak was confirmed at about 250-400 nm, and 475 nm emission was observed under 316 nm excitation. As mentioned in the introduction, incident photons tend to deposit all the energy on the photoelectrons generated by interacting with CdTe, a nanomaterial of high atomic number, through the photoelectric effect. This energy goes through an energy cascade process, where the plastic matrix and dye are excited to generate excitons. Energy transfer characteristics are maximized through fluorescent dyes. Typically, through the FRET pro-cess, energy is transferred between molecules. As the nanomaterials were loaded, the emission wavelength shifted through the FRET process and the emission intensity increased. This means that compared to conventional fluorescent dyes, quantum efficiency is increased due to nanomaterials, and thus greater fluorescence is generated. Figure 5: **(a)** Real picture of the performance experimental setup for gamma energy spectrum using a functional plastic scintillator. **(b)** Real picture of integrated device box and portable probe with a functional scintillator. **(c)** Schematic illustration for plastic detection system. To compare the performance of a plastic scintillator produced by adding CdTe material with a commercial scintillator, a measurement test was performed by placing a source at a distance of 20 mm from the scintillator surface. Considering the half-life, the radioactivity of the Cs-137 source is 342.28 kBq. Unlike inorganic scintillators, plastic scintillators rarely generate photoelectric effects, and Compton scattering mainly occurs. Compton edge energies of Cs-137 used in this experiment are 477.3 keV. Since the plastic scintillator is dominated by Compton scattering, energy calibration was performed using the Compton edge and measurement tests were performed for 10 min. The results of the measurement test using a point source for each plastic scintillator are shown in Figure 6. Additionally, the result of calculating the output by gross count of the measured spectrum is shown in the Table 2. The relative efficiency of the CdTe-loaded plastic scintillator was calculated using Equation (2) as the gross counting method for the commercial plastic scintillator, and as a result, it was confirmed that it increased by 25% compared to the commercial plastic scintillator. However, the measurement result using the point source analyzed that the Compton edge of commercial plastics has better resolution. This is because of the transmission loss due to Rayleigh scattering, and aggregation of a solid form CdTe nanomaterials. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & **Net Count** & **Relative** & **Detection** \\  & & **(cps)** & **Efficiency** & **Efficiency** \\ \hline Commercial & 20 mm & 3,644,431 \(\pm\) 495,634 & 100.00 & 2.09 \\ plastic & 50 mm & 1,332,009 \(\pm\) 99,208 & 100.00 & 0.76 \\  & 100 mm & 474,203 \(\pm\) 23,352 & 100.00 & 0.27 \\ \hline Plastic without & 20 mm & 1,803,557 \(\pm\) 2657 & 49.49 & 1.03 \\ CdTe & 50 mm & 781,528 \(\pm\) 582 & 58.67 & 0.45 \\  & 100 mm & 303,323 \(\pm\) 53 & 63.96 & 0.17 \\ \hline Plastic with & 20 mm & 4,100,748 \(\pm\) 558,312 & 112.52 & 2.35 \\ CdTe & 50 mm & 1,608,902 \(\pm\) 120,952 & 120.79 & 0.92 \\  & 100 mm & 593,654 \(\pm\) 331 & 125.19 & 0.34 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Compared relative efficiency for detection of radioactive cesium.