Investigation of the effective atomic number dependency on kinetic energy using collision stopping powers for electrons, protons, alpha, and carbon particles.

As an important component in medical applications, dosimetry, and radiotherapy studies, the effective atomic number of body tissue, tissue equivalent substances, and dosimetry compounds are investigated. In this research, considering the Coulomb interaction of charged particles, using the collision stopping power and the NIST library data, the effective atomic number of various materials at different energies is calculated for common radiotherapy particles such as electron, proton, alpha, and carbon ions. Taking into account the direct calculation method based on the collision stopping power, the effective atomic number for electron, proton, alpha, and carbon particles is determined for a group of dosimetry and tissue equivalent materials. Results of the calculations based on the collision stopping power showed that in low kinetic energy, the values of the effective atomic number are equal to the total number of electrons in each molecule of the compound, which is quite justified by the physics of Bethe's formulas.

Introducing a novel low energy gamma ray shield utilizing Polycarbonate Bismuth Oxide composite.

The fabrication of different weight percentages of Polycarbonate-Bismuth Oxide composite (PC-Bi2O3), namely 0, 5, 10, 20, 30, 40, and 50 wt%, was done via the mixed-solution method. The dispersion state of the inclusions into the polymeric matrix was studied through XRD and SEM analyses. Also, TGA and DTA analyses were carried out to investigate the thermal properties of the samples. Results showed that increasing the amount of Bi2O3 into the polymer matrix shifted the glass transition temperature of the composites towards the lower temperatures. Then, the amount of mass attenuation coefficients of the samples were measured using a CsI(Tl) detector for different gamma rays of 241Am, 57Co, 99mTc, and 133Ba radioactive sources. It was obtained that increasing the concentration of the Bi2O3 fillers in the polycarbonate matrix resulted in increasing the attenuation coefficients of the composites significantly. The attenuation coefficient was enhanced twenty-three times for 50 wt% composite in 59 keV energy, comparing to the pure polycarbonate.