Gamma-Ray Protection Properties of Bismuth-Silicate Glasses against Some Diagnostic Nuclear Medicine Radioisotopes: A Comprehensive Study

Gamma Attenuation Features of White Cement Mortars Reinforced by Micro/Nano Bi2O3 Particles

This study aims to explore the radiation protection properties of white mortars based on white cement as a binder and Bi₂O₃ micro and nanoparticles in proportions of 15 and 30% by weight as replacement sand. The average particle size of micro- and nano-Bi₂O₃ was measured using a transmission electron microscope (TEM). The cross-sectional morphology and distribution of Bi₂O3 within the samples can be obtained by scanning electron microscopy (SEM), showing that nanoscale Bi₂O₃ particles have a more homogeneous distribution within the samples than microscale Bi₂O₃ particles. The shielding parameters of the proposed mortars were measured using the HPGe detector at various γ-ray energies emitted by standard radioactive point sources ²⁴¹Am, ¹³³Ba, ⁶⁰Co, ¹³⁷Cs, and ¹⁵²Eu. The experimental values of the prepared mortars' mass attenuation coefficients (MAC) match well with those determined theoretically from the XCOM database. Other shielding parameters, including half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective electron density (N_eff), effective atomic number (Z_eff), equivalent atomic number (Z_eq), and exposure buildup factor (EBF), were also determined at different photon energies to provide more shielding information about the penetration of gamma radiation into the selected mortars. The obtained results indicated that the sample containing 30% by weight of nano Bi₂O₃ has the largest attenuation coefficient value. Furthermore, the results show that the sample with a high concentration of Bi₂O₃ has the highest equivalent atomic numbers and the lowest HVL, TVL, MFP, and EBF values. Finally, it can be concluded that Bi₂O₃ nanoparticles have higher efficiency and protection compared to microparticles, especially at lower gamma-ray energies.

A closer look at the efficiency calibration of LaBr3(Ce) and NaI(Tl) scintillation detectors using MCNPX for various types of nuclear investigations

The nuclear spectroscopy method has long been used for advanced studies on nuclear physics. In order to decrease costs and increase the efficiency of nuclear radiation investigations, quick and efficient solutions are required. The purpose of this research was to calculate the whole energy peak efficiency values for a range of gamma-ray energies, from 30.973 keV to 1408 keV, at various source-detector distances using the MCNPX Monte Carlo code, which is extensively used in nuclear medicine, industry, and scientific research. As a result, the modeled detectors' full-energy peak efficiencies were calculated and compared to both experimental data and Monte Carlo simulations. Experiment results and prior studies using Monte Carlo simulations were found to be very consistent with these results. The counting efficiency against source-detector distance is then calculated using the modeled detectors. The data we have show that LaBr₃(Ce) has outstanding detection properties. This study’s findings might be used to improve the design of detectors for use in wide range of high-tech gamma spectroscopy and nuclear research applications.

Calculation of NaI(Tl) detector efficiency using 226Ra, 232Th, and 40K radioisotopes: Three-phase Monte Carlo simulation study

Thallium-activated sodium iodide (NaI(Tl)) detectors can be used in gamma cameras, environmental radiation assessments, including radiation emission levels from nuclear reactors, and radiation analysis equipment. This three-phase investigation aimed to model a standard NaI(Tl) detector using the Monte Carlo N-Particle eXtended (MCNPX) general-purpose Monte Carlo simulation techniques. Accordingly, a standard NaI(Tl) detector was designed along with the required properties. Next a validation study of the modelled NaI(Tl) detector has been performed based on the experimental results for absolute detector efficiency values obtained from 226Ra, 232Th, and 40K radioisotopes. Our findings indicate that the obtained absolute detector efficiency values are quite close to used experimental values. Finally, we used the modelled detector for determination of mass attenuation coefficients of Ordinary concrete, Lead, Hematite-serpentine concrete, and Steel-scrap concrete at 186.1, 295.22, 351.93, 609.31, 1120.29, 1764.49, 238.63, 911.2, 2614, and 1460.83 keV gamma-ray energies. Additionally, according to our findings, mass attenuation coefficients obtained from the newly designed detector are compatible with the standard NIST (XCOM) data. To conclude, continuous optimisation procedures are strongly suggested for sophisticated Monte Carlo simulations in order to maintain a high degree of simulation reliability. As a result, it can be concluded that the validation of the simulation model is necessary using measured data. Finally, it can also be concluded that the validated detector models are effective instruments for obtaining basic gamma-ray shielding parameters such as mass attenuation coefficients.

Study on the Design, Preparation, and Performance Evaluation of Heat-Resistant Interlayer-Polyimide-Resin-Based Neutron-Shielding Materials

Polymers have an excellent effect in terms of moderating fast neutrons with rich hydrogen and carbon, which plays an indispensable role in shielding devices. As the shielding of neutrons is typically accompanied by the generation of γ-rays, shielding materials are developed from monomers to multi-component composites, multi-layer structures, and even complex structures. In this paper, based on the typical multilayer structure, the integrated design of the shield component structure and the preparation and performance evaluation of the materials is carried out based on the design sample of the heat-resistant lightweight polymer-based interlayer. Through calculation, the component structure of the polymer-based materials and the three-layer thickness of the shield are obtained. The mass fraction of boron carbide accounts for 11% of the polymer-based material. Since the polymer-based material is the weak link of heat resistance of the multilayer shield, in terms of material selection and modification, the B₄C/TiO₂/polyimide molded plate was prepared by the hot-pressing method, and characterization analysis was conducted for its structure and properties. The results show that the ball milling method can mix the materials well and realize the uniform dispersion of B₄C and TiO₂ in the polyimide matrices. Boron carbide particles are evenly distributed in the material. Except for Ti, the other elemental content of the selected areas for mapping is in good agreement with the theoretical values of the elemental content of the system. The prepared B₄C/TiO₂/polyimide molded plate presents excellent thermal properties, and its glass transition temperature and initial thermal decomposition temperature are as high as 363.6 °C and 572.8 °C, respectively. In addition, the molded plate has good toughness performs well in compression resistance, shock resistance, and thermal aging resistance, which allows it to be used for a long time under 300 °C. Finally, the prepared materials are tested experimentally on an americium beryllium neutron source. The experimental results match the simulation results well.

Multiple Assessments on the Gamma-Ray Protection Properties of Niobium-Doped Borotellurite Glasses: A Wide Range Investigation Using Monte Carlo Simulations

In this study, the monotonic effect of Ta2O5 and ZrO2 in some selected borotellurite glasses was investigated in terms of their impact on gamma-ray-shielding competencies. Accordingly, three niobium-reinforced borotellurite glasses (S1 : 75TeO2 + 15B2O3 + 10Nb2O5, S2 : 75TeO2 + 15B2O3 + 9Nb2O5 + 1Ta2O5, and S3 : 75TeO2 + 15B2O3 + 8Nb2O5 + 1Ta2O5 + 1ZrO2) were modelled in the general-purpose MCNPX Monte Carlo code. They have been defined as an attenuator sample between the point isotropic gamma-ray source and the detector in terms of determining their attenuation coefficients. To verify the MC results, attenuation coefficients were then compared with the Phy-X/PSD program data. Our findings clearly demonstrate that although some behavioral changes occurred in the shielding qualities, modest improvements occurred in the attenuation properties depending on the modifier variation and its magnitude. However, the replacement of 2% moles of Nb2O5 with 1% mole of Ta2O5 and 1% mole of ZrO2 provided significant improvements in both glass density and attenuation properties against gamma rays. Finally, the HVL values of the S3 sample were compared with some glass- and concrete-shielding materials and the S3 sample was reported for its outstanding properties. As a consequence of this investigation, it can be concluded that the indicated type of additive to be added to borotellurite glasses will provide some advantages, particularly when used in radiation fields, by increasing the shielding qualities moderately.

A detailed investigation on highly dense CuZr bulk metallic glasses for shielding purposes

Gamma-ray shielding properties of eight different metallic glasses based on CuxZr100-x: x = 35 (Cu35Zr65) − 70 (Cu70Zr30) were determined using Monte Carlo simulations and Phy-X/PSD software. A typical gamma-ray transmission setup has been modeled in MCNPX Monte Carlo code. The general trend of the linear attenuation coefficients (μ) was reported as (μ)Cu35Zr65 < (μ)Cu40Zr60 < (μ)Cu45Zr55 < (μ)Cu50Zr50 < (μ)Cu55Zr45 < (μ)Cu60Zr40 < (μ)Cu65Zr35 < (μ)Cu70Zr30. In terms of half value layer (HVL) values, the Cu35Zr65 sample has the highest value (2.984 cm) and the Cu70Zr30 sample has the lowest value (2.769 cm) at 8 MeV photon energy. The mean free path (MFP) values were 4.305 and 3.995 cm for Cu35Zr65 and Cu70Zr30 samples, respectively. Generally, MFP and HVL values of the studied glasses were reported as (MFP,HVL)Cu35Zr65 > (MFP,HVL)Cu40Zr60 > (MFP,HVL)Cu45Zr55 > (MFP,HVL)Cu50Zr50 > (MFP,HVL)Cu55Zr45 > (MFP,HVL)Cu60Zr40 > (MFP,HVL)Cu65Zr35 > (MFP,HVL)Cu70Zr30 for all photon energy range. The Cu70Zr30 sample showed maximum values of both the effective conductivity (C eff) and effective electron density (N eff). In addition, the Cu70Zr30 sample has minimum exposure and energy absorption buildup factor (EBF and EABF) values at all studied gamma-ray energies. The results revealed that the Cu70Zr30 sample has superior attenuation properties among all studied samples.