The integration of photon and neutron method for contrabands detection with a 7MeV LINAC

X-ray and neutron play both very important roles to the detection of concealed contrabands. X-ray imaging is the most popular method for its excellent penetrating capability and superb spatial resolution. While the lack of material identification capability limits its application. The combination of photon and neutron would provide better performance. Here we present the contraband detection method research based on photon and neutron interrogation. Both photon and neutron are produced by the same 7MeV LINAC. Bremsstrahlung photons are collimated to form the X-ray imaging while the unused photons are converted to photoneutrons. The contrabands information is stimulated by both photons and photoneutrons. Photon-atom reactions are used to attenuate photons to form the X-ray penetration image indicating mass thickness information. Neutron scattering reaction is used to attenuate photoneutron to form the neutron penetration image. The two attenuation information then is fused together to form a new factor indicating different materials. The combination of photoneutron imaging and X-ray imaging is then called PNXR (PhotoNeutron X-ray Radiography). Hydrogen wealthy material, organic material, light metal and heavy metal can be separated with PNXR successfully. Neutron and photon induced fissions are used to find and confirm the existence of nuclear materials. The β-delayed neutrons are measured by the same neutron detector array of PNXR but within a delayed time window (2~6 ms) after each X-ray pulse. Neutron radiative capture reaction is used for the confirmation of suspected explosive material that has been specified as organic material by PNXR. Gamma-ray of 10.828, 2.223 and 7.64 MeV is detected by NaI(Tl) array to show the 2-dimension concentration of nitrogen, hydrogen and iron. More than 4 kinds of different interaction are used in this system and they are all produced by the same 7 MeV LINAC. The integration of them has been proved to be effective.