Optimization of 241Am-NaI(Tl) gamma backscattering system for detection of hidden explosives and drugs

Experiments were carried out to explore the performance of the gamma back-scattering technique in detection and localization of contrabands such as; TNT (C7H5N3O6), codeine (C18H21NO3) hidden in hollow plastic tubes. This is done using an assembly consisting of 241Am gamma source, producing about 5×107 photon.s-1, in conjunction with a NaI(Tl) detector. The source-detector distance was optimized and the optimal configuration was selected to scan the two samples each in turn. The results in terms of contrast ratios and Figure of Merit verified the capability of the proposed device to detect and localize the targeted samples when sealed in plastic discs as small as 2.8 cm in diameter. In addition, the high contrast ratios achieved; 30% for TNT and 25% for codeine demonstrated the good distinction ability of the device.