Feasibility of using 10 MeV electron LINAC for explosives detection based on thermal neutron activation analysis: a Monte Carlo study

In the present paper, we used the MCNPX code for the feasibility of the design of a conceptional explosives detection system based on a neutron source generated by a 10 MeV electron linear accelerator (LINAC). In this study, an optimized e–γ–n converter (as a suitable neutron source) has been used for explosives detection based on thermal neutron activation analysis (TNAA) (a nondestructive technique for materials analysis). After optimization, total and thermal neutron fluxes of 4.78 × 10⁸ ± 0.63% (n/cm² mA s) and 3.95 × 10⁸ ± 0.69% (n/cm² mA s) could be obtained, respectively. Twelve LaBr₃ (3-inch) scintillator detectors have been simulated in order to calculate the response function (by the F8 tally) and to obtain a spectrum of prompt gamma of six common explosives (TNT, PETN, RDX, HMX, NG and EGDN). In these spectra, peaks of the prompt gamma of the hydrogen and nitrogen at 2.223 MeV and 10.829 MeV were observed, respectively, as the first indicator for explosives detection. The ratio of the counts under the peaks for H and N (as the second indicator for explosives detection) were also calculated. Finally, we verified the obtained results of the simulation with the theory and we showed that the results of theory and simulation have a good agreement. Therefore, the results revealed that using a 10 MeV LINAC can be a good alternative for TNAA and also for explosive detection.