(558b) GEANT4 NRF Simulation for Material Detection

Nuclear resonance fluorescence (NRF) presents a nondestructive material detection method. The NRF is a process of resonant nuclear absorption of a photon, followed by de-excitation and emission of one or more photons. It is therefore an excellent method to probe the existence of different materials in samples of interests, since each isotope has its own specific NRF spectrum signature. This signature creates a unique thumbprint that can be used to identify materials [1]. GEANT4 NRF simulation tool based on the Monte Carlo method [2], is used to model the real NRF experiment. GEANT4 is a set of particle physics Monte Carlo simulation toolkits developed by CERN. GEANT4 is an open-source code and its C++ object-oriented programming model makes it easy to be fully customized by the application developer. It provides a diverse but cohesive set of software components which can be employed in any areas where particle interactions in matter is investigated. The NRF physics process is not supported in the original GEANT4 package; The GEANT4 NRF module, called G4NRF, is developed by Pacific Northwest National Labs (PNNL) [3]. In this paper we present numerical NRF tests in detecting various materials, presence of explosives in suitcases or containers, presence of mercury in water samples, or lead in food samples, to mention just few. Figure 1 shows the GEANT4 modeling of the experimental environment. Presence of the detector ring increases the NRF signal yield and the ring is shielded by lead. The images are captured from the OpenGL output of GEANT4. Figure 2 shows the simulated NRF spectrum for two materials: carbon and lead. Based on the reading of the spectra we can detect the presence of materials in the examined samples. References [1] G.A. Warren, J.A. Caggiano, H.K. Walter, E. Lepel, S. Pratt, W. Bertozzi, S.E. Korbly, R.J. Ledoux, and W.H. Park, "Nuclear Resonance Fluorescence of 235U," Nuclear Science Symposium Conference Record, 2006. IEEE, vol. 2, 2006, pp. 914-917. [2] S. Agostinelli, et al. "Geant4?a simulation toolkit," Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 506, 2003, pp. 250-303. [3] D.V. Jordan and G.A. Warren, "Simulation of nuclear resonance fluorescence in Geant4," Proc. NSS'07, IEEE, 2007, pp. 1185-1190.