Calculation of energetic dual-energy detector efficiency using MCNP and GEANT Monte Carlo codes

The use of dual-energy detectors is a powerful tool in homeland security to identify materials atomic number in objects submitted to an X-ray analysis. In this work, the Monte Carlo methodology has been applied to study the response of a dual-energy lineal detector made of two scintillator materials, irradiated with a 160 KV photon spectrum emitted by an X-ray tube. To that, two different Monte Carlo codes have been used in the simulations, the MCNP5 and GEANT codes. The study of the energetic efficiency of a dual-energy detector has been developed by the simulation of several monoenergetic beams (10, 20, ..., 160 KeV) oriented towards the detector, and registering the absorbed energy at both scintillators in each energy bin analyzed. Different configurations of scintillators materials and thickness have been simulated and the results show that a dual-energy detector formed GOS-CdWO₄ scintillators materials is a good combination in order to separate the low energy part of the spectrum from the high energy part of it, obtaining as a result, two different images very useful for the identification of the effective atomic number of an irradiated object.