Monte Carlo study of the interaction of gamma radiation - material: application to a cobalt 60 irradiator

The present work presents an overview of application of the Monte Carlo code, GEANT4, in the gamma irradiation processing field. In order to check the validity of such code, a successful calculation of expected dose rate and photon flux in the Tunisian gamma irradiation facility was carried out. In the same course of study, an ample set of comparison tests were done using the PMMA dosimeters and the GEANT4 version 8.2 code, for measurement and calculation purposes. Thus, the excellent agreement seen between data and calculations allow us to apply the GEANT4-based tool in order to optimize some process parameters, specific to the studied 60Co facility, and to systematically improve the dose uniformity within irradiated targets having different densities and volumes. Therefore, three irradiation processing procedures were studied let us to conclude that for a given carrier dimensions, more the product density is higher than a determined value, more a specific procedure will be performed. It is shown that Monte Carlo simulation improves the gamma irradiation process understanding. (Author)