# Gamma Ray Shielding Properties of Yb\({}^{3+}\)-Doped Calcium Borotellurite Glasses
## 3 Results and Discussion
RPE measures how effective a material is at shielding radiation and is calculated as a percentage, with a greater percent meaning a better shield. The same energy range was used as previous figures. These two glasses were chosen to evaluate the effect of the TeO\({}_{2}\) content in the glasses, or the density of the glasses, on RPE. The lowest and highest thicknesses were investigated to determine if thickness has an impact on RPE. At the lowest investigated energy, 0.284 MeV, for both thicknesses, TeBYb1 has a lesser RPE than TeBYb5. For instance, for a thickness of 0.3 cm at this energy, TeBYb1 has an RPE of 10.94%, while TeBYb5 has an RPE of 18.63%. At 1.5 cm, the RPE values are 43.96% and 64.33% for TeBYb1 and TeBYb5, respectively. The results demonstrate that TeBYb5 is the more effective attenuator since it has the greater RPE at both thicknesses. This trend occurs since more photons are absorbed when the thickness of the material increases. In addition, when observing a glass at a certain thickness, its RPE value decreases as energy increases. For the TeBYb5 at 1.5 cm, the RPE decreases from 64.33% at 0.284 MeV, to 35.77% at 0.826 MeV, and 22.55% at 2.506 MeV. This decrease signifies that the protection abilities of the samples decline with the increase in photon energy, which is consistent with the results for TF. Nevertheless, TeBYb5 proves to be the better shield even at higher energies. Figure 5: The transmission factor for TeBYb5 as a function of the energy at different thicknesses. We can also present the effective atomic number (\(Z_{\rm eff}\)) as an important factor used in the radiation shielding field to understand the effectiveness of the TeBYbX glasses in blocking the incoming radiation. [PERSON] et al. (2016) explained the methods for the calculations of this parameter for all materials for E \(>\) 1 keV. From the \(Z_{\rm eff}\) we can give a conclusion about the performance of the materials against gamma radiation. The high \(Z_{\rm eff}\) for a specific attenuator implies that it is more capable at shielding the incoming radiation. Figure 7 presents the variations in \(Z_{\rm eff}\) with energy for the TeBYbX glasses. It is to be noted from Figure 7 that the \(Z_{\rm eff}\) takes the maximum values at 0.284 MeV (11.20 for TeBYb1, 12.52 for TeBYb2, 13.84 for TeBYb3, 15.79 for TeBYb4 and 20.69 for TeBYb5). These values decrease rapidly between 0.284 to 0.723 MeV. The \(Z_{\rm eff}\) varies between 9.87 and 16.14 at 0.723 MeV. The previous trend in the \(Z_{\rm eff}\) can be demonstrated by the photoelectric effect which is important at these energies. A constant trend in the \(Z_{\rm eff}\) can be seen between 0.826 and 1.333 MeV. For instance, the \(Z_{\rm eff}\) for TeBYb1 at these two energies are 9.73 and 9.82. For TeBYb5, the \(Z_{\rm eff}\) values are 15.61 and 15.95 (at 0.826 and 1.333 MeV respectively). Between these energies, Compton scattering becomes very important and it doesn't depend on the atomic number of the medium, therefore we found that the \(Z_{\rm eff}\) seems to be almost constant with the energy. Finally, at the last chosen energy (E = 2.506 MeV), the \(Z_{\rm eff}\) shows a small increase. For TeBYb1, the \(Z_{\rm eff}\) increases from 9.73 to 9.89, while it increases from 15.61 to 16.17 for TeBYb5. Moreover, we can understand from Figure 7 that the addition of TeO\({}_{2}\) causes an enhancement in the \(Z_{\rm eff}\) values. This is because TeBYb5 shows the highest values of this quantity and in contrast TeBYb1 shows the lowest \(Z_{\rm eff}\), and from Table 1, it can be  
Figure 6: The radiation protection efficiency for TeBYb1 and TeBYb5 as a function of the energy at 0.3 and 1.5 cm. seen that TeBYb1 and TeBYb5 have 10 and 54 mol% of TeO\({}_{2}\). The \(Z_{\rm eff}\) results emphasis that the glass with the composition of 54 TeO\({}_{2}\)-27.6B\({}_{2}\)O\({}_{3}\)-7.9 CaO-10 CaF\({}_{2}\)-0.5 Yb\({}_{2}\)O\({}_{3}\) is the best attenuator out of the chosen glasses. Furthermore, the efficiency of the photon shielding is characterized in terms of the HVL.