Simulation of gamma reference field at Institute for Nuclear Science and Technology using Monte Carlo method

This paper presents the characterization of two gamma reference fields of 137Cs and 60Co sources at the Institute for Nuclear Science and Technology. The characterization of the fields in terms of gamma fluence Φ, mean energy, EΦ, kerma weighted mean energies, Eₖ, air kerma, Eair, were determined at various distances from the source center by Monte Carlo simulation using MCNP6. The air kerma results were compared with the measurements obtained by using a calibrated ionization chamber. The discrepancy between the simulated and measured air kerma was less than 4.5%. The scatterred component was also simulated and calculated. The results of both methods showed that the contribution of the scattered components to the gamma reference field is less than 3%. This contribution comply with the international standard criteria of ISO 4037 (<5%). The results confirmed that the characterization of the gamma reference field could be determined using the simulation code.