## 3 Results and Discussion
Figure 6: (a) A functional plastic scintillator including CdTe. (b) UV-Vis absorbance. (c) Photoluminescence emission spectrum, excitation at 316 nm. In addition, the detection efficiency of commercial plastics and the CdTe plastic scintillator was measured. The detection efficiency was calculated using Equation (3). In Table 2, the gross count rate increased as the CdTe nanomaterial was added. This means that the high atomic number of CdTe increases the reaction rate with photons, thereby improving the efficiency. \[\text{Relative efficiency}\;(\%)=\frac{\text{Total counts}\;(\text{ CdTe loaded plastic})}{\text{Total counts}\;(\text{Commercial plastic})}\times 100 \tag{2}\]  
\[\text{Detection efficiency}\;(\%)=\frac{\text{Net counts}(\text{cps})}{ \text{Radioactivity}(\text{Bq})\times\;\text{Release Probability}(\%)}\times 100 \tag{3}\]  
Figure 7 shows the spectrum measured by radiation source distance for commercial plastics, plastics loaded with CdTe, and plastics not loaded with CdTe. The spectrum in Figure 7 shows the net count minus the background radiation, and is a graph normalized to 477.65 keV, the Compton edge energy of Cs-137. Spectral data were obtained by dividing the energy of 3 MeV by a total of 8192 channels. It was confirmed that as the distance of the radiation source increased, the number of counts decreased. Figure 8 represents the measurement data for three plastic scintillators, and it means the average value of the measured data by distance. As shown in Figure 8, it was observed that in the case of the scintillator to which the nanomaterial was added, the Compton peak was shifted to the left compared to the commercial scintillator. Based on this, the light yield  
Figure 7: Normalized energy spectrum by distance. (**a**) Commercial plastic scintillator. (**b**) Plastic scintillator with CdTe. (**c**) Plastic scintillator without CdTe. for the CdTe scintillator was calculated using the light yield of EJ-200. Light yield was calculated based on the data in Figure 8 and Equation (4) [41]. \[\text{LY}_{\text{Cd}}=\text{LY}_{\text{EJ}}\times\frac{\text{CE}_{\text{Cd}}}{ \text{CE}_{\text{EJ}}}\times\frac{\text{QE}_{\text{EJ}}}{\text{QE}_{\text{Cd}}} \tag{4}\]  
Here, LY, CE, and QE refer to the light yield, the peak channel of Compton's edge, and the quantum efficiency of PMT at the emission wavelength, respectively, and EJ and Cd refer to the commercial scintillator and the plastic scintillator loaded with CdTe, respectively. As shown in Table 3, the \(\text{LY}_{\text{EJ}}\) value was used as a reference value of 10,000 photon/MeV, a value suggested by Eljen technology. In addition, QE used the values in the datasheet of PMT (ET-9266 KB) [42]. When CdTe was loaded, it was confirmed that the light yield increased compared to commercial plastic scintillator. Based on this result, it is analyzed that the CdTe nanomaterial not only increases the reaction rate with photons, but also improves the energy transfer rate. Figure 9 shows the result of comparing the spectrum of commercial plastic scintillator (EJ-200) and CdTe-loaded plastic scintillator with MCNP simulation. The average relative error in the Compton edge region was analyzed to be within 5%. In the MCNP simulation results of Figure 7b, a signal was detected in a region larger than the Compton edge by CdTe with a high atomic number. The reason that these signals are not seen in the experimental results is likely due to the aggregation due to the low solubility and high surface energy of CdTe. In order to analyze the influence of CdTe nanomaterials, the count ratio was calculated through the Equation (5). As a result, it showed a high coefficient ratio  
Figure 8: Gamma measurement spectrum of three plastic scintillators using Cs-137 point source. Insert figure represents relative counts from channel 1000 to 1800.