International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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SM/EN-07
Acquisition of Neutron-Induced Gamma Signatures of Chemical Agents B. Perot1, C. Carasco1, J.L. MaV1, P. Pras2, E. Cusset2, R. Vogler2, M. Gmar3, G. Sannie3, and S. Normand4 1CEA, DEN, Cadarache, France Corresponding Author: bertrand.perot@cea.fr The detection of special chemical elements that could be used by terrorist in improvised explosive devices (IED) can be performed by the spectroscopic analysis of neutron-induced γ rays. Capture γ-ray detection is optimally performed by thermal neutron analysis (TNA), between the pulses delivered by a fast neutron generator. During this inter-pulse period, the ratio betweenthermal and fast neutrons reaches a maximum. On the other hand, γ rays induced by fast neutrons, e.g., in inelastic scattering reactions, can be optimally detected by using the associated particle technique (APT), which allows to improvethe signal-to-noise ratio by selecting γ rays induced by fast neutrons inside a specific volume ofinterest. In the frame of the French CBNRE R&D program, which aims at developing new detection technologiesand systems to improve the fight against chemical, biological, nuclear, radiological andexplosive threats, we propose to use both TNA and APT in a portable inspection system. The goal is to identify the largest possible panel of chemical elements of interest: fluorine, sodium,phosphorus, sulphur, chlorine, arsenic, bromine, iodine, mercury, etc. TNA and APT signatures of these elements are currently being acquired with low backgroundmeasurement systems and long acquisition times, to constitute a reference database that will be used to process the inspection data of the future portable system. The paper will present the status of this experimental database, which will provide indications about the interest to couple TNA and APT in a single inspection system. Measured signatures will be compared with γ-ray spectra calculated with MCNPX and ENDF/B–VII. |
