GEANT4 Program Monte-Carlo Simulation of Ordinary Concrete's Mass Attenuation Coefficient for Gamma Rays in the Energy Range of 10 keV to 100 MeV

The values of mass attenuation coefficient for ordinary concrete have been simulated using the software packages GEANT4 and XCOM for gamma rays whose energies range from 10 keV to 100 MeV. Both the GEANT4 simulated data, the XCOM simulated data and the theoretical prediction were in agreement. The total mass attenuation coefficient corresponds to the sum of the mass attenuation coefficients from the individual interaction processes, namely, the photoelectric effect, the Compton effect and the electron-positron pair production. The results from both GEANT4 and XCOM showed that with the increase in gamma ray energy, there was a decrease in the photoelectric mass attenuation coefficient of ordinary concrete. The results from both GEANT4 and XCOM consistently showed a decrease in Compton mass attenuation coefficient of ordinary concrete with increase in the gamma ray gamma ray energies within the above energy range. The research outcome from both simulation packages also confirmed that the electron-positron pair production mass attenuation coefficient of ordinary concrete increases with the increase in the gamma ray energy for gamma ray whose energy fall within the above range. These results were farther compared to published theoretical predictions found in textbooks. The results validated the use of GEANT4 for the simulation of gamma ray attenuation in materials. Background: The mass attenuation coefficient is a measure of a material's ability to absorb or scatter electromagnetic radiation per unit of mass . It is independent of material's density hence prefferd as an attenuation parameter. It can either be experimentally obtained or theoretically through Monte-carlo methods. The GEANT4 program is one of the MonteCarlo codes in use for such studies. This research is to validate the use of GEANT4 code in studying gamma ray attenuation in materials. Materials and Methods: The theoretical approach of Monte-carlo Simulation was employed using GEANT4 and XCOM programs to calculate the total mass attenuation coefficient for ordinary concrete. GEANT4 code and the web based XCOM code were also used to calculate the photoelectric mass attenuation coefficient, the Compton mass attenuation coefficient and the electron-positron pair production for various energies within the range of 10 keV to 100MeV. Results: Both GEANT4 and XCOM showed that the variation of the (total)mass attenuation coefficient of ordinary concrete with gamma ray energy within the range of 10 keV to 100 MeV, from GEANT4 and the XCOM program simulated results showed good consistency except at lower gamma ray energies. The XCOM and the GEANT4 program simulated results agreed that the photoelectric effect predominates at low gamma ray photon energies, the Compton effect at intermediate gamma ray energies and the pair production at high gamma ray energies. For the gamma ray photon energy within the range of 10 keV to 100 MeV, there was an agreement from XCOM and GEANT4 programs' results that the photoelectric mass attenuation coefficient and the pair production mass attenuation coefficient of ordinary concrete decrease with increase in the photon energy. However, Compton mass attenuation coefficient decrease with the increase in gamma ray photon energy. Conclusion: The research validated the use of GEANT4 program in the determination of attenuation parameters of different shielding materials.