Study of tagged neutron method with laboratory D-T neutron generator for explosive detection
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Study of tagged neutron method with laboratory D-T neutron generator for explosive detection Saroj Bishnoi1,a , T. Patel1, R. G. Thomas2 , R. Jilju1, P. S. Sarkar1, B. K. Nayak2 1 Technical Physics Division, Bhabha Atomic Research Center, Mumbai 400085, India 2 Nuclear Physics Division, Bhabha Atomic Research Center, Mumbai 400085, India
Received: 14 October 2019 / Accepted: 16 April 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Tagged neutron-based experimental system has been developed with a laboratory D-T neutron generator at BARC. The system can identify the C, N, O elemental signatures from an interrogated object (explosive or benign) using the Associated Particle Technique (also known as tagged neutron method) employing alpha–gamma coincidence and time-offlight methodology. The system consists of a matrix of 64-pixel YAP:Ce α-particle detectors incorporated in the neutron generator and a BGO (3 × 3 ) gamma detector. Main parameters of the system were investigated, and its performance was evaluated through various experiments performed at laboratory environment. The experimental results of pure element spectra (graphite for Carbon, water for Oxygen), complex sample (melamine) spectrum and study of explosive simulant (RDX) spectrum have demonstrated the successful implementation of the tagged neutron method.
1 Introduction Fast neutron interrogations have found wide use in variety of areas ranging from elemental characterization for material identification to imaging of large shipping containers in search of localized threat materials [1–4]. Development of effective non-intrusive neutron interrogation techniques for detection of concealed illicit materials including explosives and drugs is of prime importance for national security. The methodology of threat/explosive material detection rests on the principle that explosives can be distinguished from each other and from innocuous materials by analyzing the quantities and ratios of carbon (C), oxygen (O) and nitrogen (N) elements in the material [3] under investigation. Neutron interrogations, generally achieve this through fast neutron-induced (mostly via neutron inelastic scattering reaction) gamma-ray spectroscopy. A neutron source irradiates a sample to excite the constituent element nuclei, which then de-excite with the emission of element-specific characteristic gamma rays (Table 1). The yield of characteristics/specific gamma rays in the recorded energy spectrum is directly related to the amount of the corresponding element and allows determining the relative proportions of carbon, oxygen and nitrogen, so as to differentiate illicit materials from benign ones. The common neutron techniques which have been explored for threat detection in bulk material inspection (airline bags, air/sea cargo, truck, etc.) are mainly thermal neutron anal-
a emails: [email protected]; [email protected] (corresponding author)
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