In the present work, high density polyethylene (HDPE) matrix mixed with micro-sized and nano-sized Cadmium oxide (CdO) particles of different concentrations were prepared by compression molding technique. The aim of the study is to investigate the effect of particle size and weight percentage of CdO particles on the gamma radiation shielding ability of CdO/HDPE composites. The mass attenuation coefficients of pure HDPE, micro-CdO/HDPE and nano-CdO/HDPE composites were evaluated at photon energies ranging from 59.53 keV to 1408.01 keV using standard radioactive point sources [²⁴¹Am, ¹³³Ba, ¹³⁷Cs, ⁶⁰Co and ¹⁵²Eu]. Adding micro and nano CdO particles to the HDPE matrix clearly increases the mass attenuation coefficients of the composites and the improvement is more significant at low γ-ray energies. The effect of particle size of CdO filler has an important role on the shielding ability of the composite. The experimental results reveal that, the composites filled with nano-CdO have better γ-radiation shielding ability compared to that filled with micro-CdO at the same weight fraction. A relative increase rate of about 16% is obtained with nano-CdO content of 40 wt% at 59.53 keV, which attributed to the higher probability of interaction between γ-rays and nanoparticles. From this study, it can be concluded that nano-CdO has a good performance shielding characteristic than micro-CdO in HDPE based radiation shielding material.

Polymers are often used in medical applications, therefore, some novel polymers and their interactions with photons have been studied. The gamma-ray shielding parameters for Polymethylpentene (PMP), Polybutylene terephthalate (PBT), Polyoxymethylene (POM), Polyvinylidenefluoride (PVDF), and Polychlorotrifluoroethylene (PCTFE) polymers were determined using the Geant4 simulation and discussed in the current work. The mass attenuation coefficients (μ/ρ) were simulated at low and high energies between 0.059 and 1.408 MeV using different radionuclides. The accuracy of the Geant4 simulated results were checked with the XCOM software. The two different methods had good agreement with each other. Exposure buildup factor (EBF) was calculated and discussed in terms of polymers under study and photon energy. Effective atomic number (Z_eff) and electron density (N_eff) were calculated and analyzed at different energies. Additionally, the half-value layer (HVL) of the polymers was evaluated, and the results of this parameter showed that PCTFE had the highest probability of interaction with gamma photons compared to those of the other tested polymers.

It is well known that materials with lead (Pb) content are very effective as protective materials against radiation. Natural rubber (NR) has been loaded with 30 phr of N220 black (critical concentration) as a conductive and reinforcing filler. These rubber matrices are loaded with different concentrations of Pb powder (up to 100 phr) as filler. Gamma attenuation study was carried out using 3″ × 3″ NaI (Tl) (scintillation detector) gamma-ray spectrometer for (Cs-137), (Co-60), (Ba-133), and (Eu-152). The effect on the shielding property of Pb/NR composite was studied by varying the content of Pb and photon energy. It was found that the addition of Pb filler remarkably increases the linear attenuation coefficient (μ) of Pb/NR composites, especially for low photon energy. Linear attenuation coefficient experimental measures and theoretical calculations (using the XCOM code) were performed. It was noted that there is a reasonable agreement between measured and calculated results. In this paper, gamma-ray radiation shielding parameters are also studied for composites based on waste rubber. Its experimental results showed that Pb/W/NR composites have better γ shielding ability compared to Pb/NR ones at the Pb contents so, these are promising materials for fabricating protecting clothes against radiation in addition to their low cost and effective aid to get a clean environment.

The aim of this study is to investigate the radiation shielding properties of novel concrete samples with bulk Bi₂O₃ and Bi₂O₃ nanoparticles (Bi₂O₃ NP) incorporated into its composition. The mass attenuation coefficient of the concrete samples without Bi₂O₃ and with 5 and 7 wt% bulk Bi₂O₃ were experimentally determined and were compared against values obtained using the XCOM and Geant4 simulations. Both methods greatly agree with the experimental values. The linear attenuation coefficients (LAC) of blank concrete (C-0), concrete with 5% bulk Bi₂O₃ (C-B5), and concrete with 5% nanoparticle Bi₂O₃ (C-N5) were determined and compared at a wide energy range. We found that the LAC follows the trend of C-0 < C-B5 < C-N5 at all the tested energies. Since both C-B5 and C-N5 have a greater LAC than C-0, these results indicate that the addition of Bi₂O₃ improves the shielding ability of the concretes. In addition, we investigated the influence of nanoparticle Bi₂O₃ on the LAC of the concretes. The half-value layer (HVL) for the concretes with bulk Bi₂O₃ and Bi₂O₃ nanoparticles is also investigated. At all energies, the C-0 has the greatest HVL, while C-N15 has the least. Thus, C-N15 concrete is the most space efficient, while C-0 is the least space efficient. The radiation protection efficiency (RPE) of the prepared concretes was found to decrease with increasing energy for all five samples. For C-0, the RPE decreased from 63.3% at 0.060 MeV to 13.48% at 1.408 MeV, while for C-N15, the RPE decreased from 87.9 to 15.09% for the same respective energies. Additionally, C-N5 had a greater RPE than C-B5, this result demonstrates that Bi₂O₃ NP are more efficient at shielding radiation than bulk Bi₂O₃.