## 3 Result and Discussion
### Radiation Attenuation Studies
Both TF and RPE were investigated for the fabricated glasses and presented in Figure 9 versus the incident gamma-ray photon. Figure 9 shows that the TF values at low gamma-ray energy up to 0.1 MeV are very small due to the photoelectric interaction, which consumes the low energy of photons totally in the interaction to produce a free electron. As a result, the photon is absorbed inside the fabricated SBT-n glasses, and the probability of scattering or escaping photons from the fabricated materials is very low. Thus, the TF values tend to be minimum values. With increasing the incident gamma-ray energy, some photons began to pass enough energy to penetrate and transmit the fabricated material. This is due to the change in the photon interaction mode where the photoelectric interaction decreases and the Compton scattering interaction begins to be the dominant interaction. Hence, the scattering and penetrated photons increase. The TF values increase gradually with increasing the CS interaction until maximum values at 8 MeV. The TF values for a thickness of 1 cm of the fabricated samples reach 88.68, 87.83, 85.95, and 83.11% for  
Figure 8: The samples’ thickness equal to 1 cm of lead at different gamma-ray energy. glasses SBT-Ti, SBT-Zn, SBT-Ba, and SBT-Pb, respectively. After that, a slight decrease in the TF values was observed when the photon energy raised above 8 MeV due to the pair production interaction in which the probability of photon annihilation increased when the photon energy increased more than 1.024 MeV. In contrast, Figure 9b illustrates the RPE variation versus the incident gamma photon energies, where the first look demonstrates that the RPE is totally opposite to the TF. The RPE at low energy is close to 100% because of the high absorption cross-section of the fabricated glasses for the low-energy photons. Thus, all photons with energy lower than 0.15 MeV are absorbed inside the glass layer and can't penetrate a thickness of 1 cm of the fabricated glass samples. Above 0.15 MeV, the scattered photons from the fabricated glass thickness increased, and the number of photons penetrating the thickness began to increase with photon energy. Thus, the RPE reduced gradually with energy until minimum RPE was achieved at 8 MeV. The minimum RPE is 11.32, 12.17, 14.05, and 16.89% for samples SBT-Ti, SBT-Zn, SBT-Ba, and SBT-Pb, respectively. Figure 10 illustrates the effect of glass thickness on the TF and RPE values. It is clear that from Figure 10a, the TF decreases gradually with growing the glass thickness where the TF values reduced between 88.76 and 30.36% (for SBT-Ti), 77.74 and 28.39% (for SBT-Zn), 75.93 and 25.239% (for SBT-Ba), 72.353 and 19.819% (for SBR-Pb) when the glass thickness grow between 0.5 and 4 cm, respectively, for gamma-ray energy of 1 MeV. Raising the glass thickness increases the probability of gamma-ray interaction along their path length. Thus, the photon loses a high amount of its energies in collusions and does not have enough power to penetrate the material thickness. As a result, the TF values decrease with growing the fabricated glasses thickness. Figure 9: (**a**) Variation of the transmission factor (TF) and (**b**) the radiation protection efficiency (RPE) versus the gamma-ray energy. In contrast, the RPE increases gradually with growing the fabricated glass thickness, as illustrated in Figure 10b. The mentioned figure showed that the low values of RPE achieved at the thinner thicknesses are related to the TF of the gamma photons. For thinner thicknesses, the photons TF is relatively high, so a lot of photons can penetrate the shielding thickness and reach the human cells beyond the shielding. Thus, the RPE offered by this shielding thickness is relatively low. With growing the glass thickness, the TF decreases, as mentioned earlier, so the number of photons penetrating the thickness becomes small, and the RPE increases.