Detection of high-Z materials using 7MeV X-rays scattering

By detecting and analyzing positron annihilation photons, bremsstrahlung photons and Compton scattered photons that are produced after the interaction of X-rays and matter, atomic number may be identified to find concealed SNM (special nuclear material). A code of reading and analyzing data from PTRAC card from MCNP5 simulation has been designed to explore the birth history of each photon. The simulation results indicate that the optimum detection angle is 145 degree and show that the information of Z (especially for high Z) of inspected materials can be extracted effectively. An experimental facility based on 7 MeV LINAC and LaBr₃(Ce) detector has been set up for experimental study. Preliminary results demonstrate the possibility of high Z materials identification.