| 摘要 |
The process to detect concealed items incorporating hydrogenous matter, involves scanning the substance by a screened, essentially mono-energetic neutron source with collimator and detector. The process involves detecting concealed items incorporating hydrogenous matter by scanning them by a screened, essentially mono-energetic neutron source with collimator and detector. The neutron detector system is especially discriminatory and detects back-scatter. The neutron source generates neutrons in the energy range 2.3 to 3 MeV or 7 to 9 MeV from the reaction 2H(d, n), 3H(p, n), 1J(t, n), 7Li(p, n) and 11B(p, n). In a preferred embodiment the instrument determines the flow depression due to hydrogen and the flow enhancement arising from elastic scatter arising from other light elements contained within the target substance e.g. carbon, nitrogen and oxygen in the respective neutron energy spectrum. This information increases contrast and minimizes the false alarm rate. An Independent claim is also included for an assembly with an electronic processing unit which discriminates between neutrons having different energy levels and which evaluates the flux depressions in the upper energy range using the different effect on the neutrons scattered by hydrogen atoms. |
