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Distortions caused by scattered neutrons and induced radiation are significant factors in fast neutron radiography (FNR). A 14 MeV fast neutron radiography system with associated particle technique (APT) has been developed in our laboratory for the application in special nuclear material (SNM) quality detection. To estimate the feasibility of the system to reduce the effects of non-direct transmission neutrons, a theoretical FNR system with APT has been developed with Geant4 toolkit. The simulation results showed that a 5 ns time window was good enough to remove 56.4% non-direct transmission neutrons and effectively improve the signal to noise ratio (SNR). Non-direct transmission neutrons in the time window following a Gaussian distribution indicated that they could be removed by Point Scattered Function (PScF). The attenuation image proved that a 5 ns time window and neutron detector with position resolution of 1 mm could effectively improve the contrast of image. The preliminary results suggest that FNR with APT could be a feasible technique in SNM quality detection. [ABSTRACT FROM AUTHOR]

The associated particle (AP) technique has recently been used with a high-purity germanium γ -ray spectrometer to assess its capability to improve field identification of recovered chemical warfare (CW) materiel through prompt gamma-ray neutron activation analysis (PGNAA) measurements. A particularly challenging pair of CW agents commonly found in recovered munitions are phosgene (CG) and cyanogen chloride (CK), which have two of three elements in common, i.e. chlorine and carbon, but differ in the third being either oxygen or nitrogen. The detection of both latter elements is complicated by high oxygen concentration in the field environment which interferes with the small signal produced from the chemical agents. The matter is further complicated by the precautionary field practice of overpacking recovered munitions with vermiculite in larger steel multiple round containers (MRCs), which places additional oxygen-rich material in contact with the munition while further attenuating an already weak signal emitted from the munition center. This work reports quantitative results from realistic field measurements of CG and CK simulants in mock 4.2-inch (11 cm) mortar rounds overpacked with vermiculite in a large MRC. Results obtained with the AP technique are compared to those obtained with the traditional PGNAA approach for both overpacked- and bare-munition measurements. The AP technique is shown to provide a much more confident discrimination between the two chemicals, particularly for the more challenging field-relevant overpacked measurements, where a significant gain in sensitivity to all the key elements (chlorine, carbon, nitrogen and oxygen) is achieved. • Associated Particle (AP) technique allows better discrimination between phosgene and cyanogen chloride in recovered chemical munitions. • Improved prompt gamma-ray neutron activation analysis (PGNAA) sensitivity to key elements C, N, O, and Cl with AP technique. • Achieved success for field-relevant measurements of overpacked munitions in multiple round containers (MRCs). • Strong suppression of background oxygen enables better discriminability and sensitivity. [ABSTRACT FROM AUTHOR]

An integrated mobile system for port security is presented. The system was designed to perform passive measurements of neutrons and γ-rays to search and identify radioactive and special nuclear materials as well as for the active investigations by using the tagged neutron inspection technique of suspect dangerous materials. The discrimination between difficult-to-detect uranium samples and high Z materials as lead was specifically studied. The system has been employed in laboratory detection tests and in a seaport field test. [ABSTRACT FROM AUTHOR]

In the frame of the French trans-governmental R&D program against CBRN-E threats, CEA (French Alternative Energies and Atomic Energy Commission) is studying the detection of Special Nuclear Materials (SNM) by neutron interrogation with the Associated Particle Technique (APT). Coincidences including at least 3 fission neutrons or gamma rays induced by tagged neutrons are used to detect and distinguish SNM from benign materials in which lower multiplicity events of 1 or 2 particles are produced by (n,2n) or (n,n’\gamma) reactions. Coincidences are detected by fast plastic scintillators and correlated with tagged neutrons to improve the signal-to-noise ratio. Dedicated data acquisition electronics (DAQ) have been developed with independent FPGA cards associated with each detector, so that the acquisition window can be opened by any of the plastic scintillators. DAQ tests in passive mode are presented, in which acquisition is triggered by the sum signal of all detectors. The system time and energy calibration and resolution are reported, as well as the qualification of numerical simulations thanks to experimental data acquired with simple setups using a ^252Cf source. Numerical studies for the design and performance of cargo container inspection are also performed with the MCNP-PoliMi computer code and the ROOT data analysis package. SNM detection in iron matrix is quite straightforward, but in organic matrix, data processing will need to combine more information to evidence SNM. [ABSTRACT FROM PUBLISHER]

Abstract: In this work we present the implementation and characterization of a (secondary ion) tritium beam generated through the D(d,t)p reaction, at deuteron energies of 2.0 and 1.88MeV, tagging the tritium ions with the associated particle technique. In order to prove its utility as a projectile for scientific applications, this beam was made to impinge on a thin gold target to observe expected elastic scattering events. [Copyright &y& Elsevier]

High-resolution prompt γ -ray neutron activation analysis (PGNAA) is performed using the associated particle (AP) technique with a deuterium–tritium neutron generator and high-purity germanium detector. Although the time resolution is inferior compared to similar systems employing fast scintillation γ -ray detectors, the strong background suppression combined with the high γ -ray energy resolution provides an important boost in sensitivity to certain key elements, especially relevant to field measurements of complex chemicals encased within thick layers of metal, such as in recovered chemical warfare (CW) munitions. Results for various CW and explosive simulants contained within mock munitions are presented and compared with results obtained from traditional PGNAA measurements without the aid of the AP technique. Significant improvements in identification and discrimination between certain chemicals are achieved with the high energy resolution AP technique. [ABSTRACT FROM AUTHOR]

A technique of laser-etching repeating micrometer-scale structures into the exit surface of a thin, YAP:Ce scintillator to increase light extraction has been performed. Different etching techniques were performed on a single, monolithic crystal using varying laser power to study how light extraction is influenced by these different treatments. For the best case, a 90.4% increase in light extraction was measured without optical coupling, which compares to photonic crystal techniques. This technique finds application in associated particle imaging (API) where no optical coupling can be used for the alpha detector's scintillator, inside the Deuterium-Tritium (D-T) neutron generator vacuum. The surface characteristics of each treatment are quantified, and changes in light collection relative to a normal, polished surface are presented. Measurement of the number of detected photons is given for the case where no optical coupling is used between the scintillator and photosensor. Additionally, implications of performance improvements in YAP:Ce based alpha transducers within D-T generators, due to the measured increases in light collection, are presented. [ABSTRACT FROM PUBLISHER]

Abstract: The French Alternative Energies and Atomic Energy Commission (CEA) is conducting an R&D program to improve the characterization of long lived and medium activity radioactive waste packages with nondestructive nuclear measurements. Neutron interrogation with the “Associated Particle Technique” (APT), which brings 3D information about waste materials composition, was studied by numerical simulation with the MCNP computer code [1] and MODAR data analysis software [2]. The design of the system is first presented, especially shields and collimators used to limit the detectors count rate because of the intense gamma emission of the waste. The random background due to the neutron generator was also limited by a specific shield as recommended earlier [3]. Then the paper presents numerical simulations illustrating the ability of APT to characterize specific volumes of interest filled with different materials (iron, water, aluminum, PVC, oil) in different waste packages. Main limitations are also identified, such as neutron scattering in the dense, hydrogenous waste matrices. [Copyright &y& Elsevier]

Abstract: A novel gamma-ray spectral analysis method has been demonstrated to optimally extract the signals of the signature elements of explosives, carbon (C), nitrogen (N) and oxygen (O) from 57–155mm projectiles following tagged neutron interrogation with 14MeV neutrons. The method was implemented on Monte Carlo simulated, synthetic spectra of Unexploded Ordnance (UXO) that contained high explosive fillers (Composition B, TNT or Explosive D) within steel casings of appropriate thicknesses. The analysis technique defined three broad regions-of-interest (ROI) between 4–7.5MeV of a spectrum and from a system of three equations for the three unknowns namely C, N and O, the maximum counts from each of these elements were extracted. Unlike conventional spectral analysis techniques, the present method included the Compton continuum under a spectrum. For a neutron output of ∼2×107 ns−1 and using four 12.7cm diameter×12.7cm NaI(Tl) detectors, the C/N and C/O gamma-ray counts ratios of the explosive fillers were vastly different from that of an inert substance like sand. Conversion of the counts ratios to elemental ratios could further discriminate the different types of explosive fillers. The interrogation time was kept at ten minutes for each projectile. [Copyright &y& Elsevier]

Abstract: Fast neutron interrogation with the associated particle technique can be used to identify explosives in cargo containers (EURITRACK FP6 project) and unexploded ordnance on the seabed (UNCOSS FP7 project), by detecting gamma radiations induced by 14MeV neutrons produced in the 2H(3H,α)n reaction. The origin of the gamma rays can be determined in 3D by the detection of the alpha particle, which provides the direction of the opposite neutron and its time-of-flight. Gamma spectroscopy provides the relative counts of carbon, nitrogen, and oxygen, which are converted to chemical fractions to differentiate explosives from other organic substances. To this aim, Monte Carlo calculations are used to take into account neutron moderation and gamma attenuation in cargo materials or seawater. This paper presents an experimental verification that C, N, and O counts are correctly reproduced by numerical simulation. A quantitative comparison is also reported for silicon, iron, lead, and aluminium. [Copyright &y& Elsevier]

D-T neutron generators have been used as an active interrogation source for associated particle imaging techniques. The D-T reaction yields a 14-MeV neutron and an alpha particle. The kinetics of the reaction allow the directionality and timing of the neutron to be determined utilizing position sensitive detectors for both the alpha and neutron. This information may be used for imaging applications. Since position and timing are required to form images, improved certainty in directional and timing will result in improved imaging performance. This requires maximum light transmission from its origin in the scintillator to conversion at the photosensor. This work is a study of the timing resolution of a first generation associated particle detector. An optical transport code, coupled with a timing model is also used to simulate the timing resolution. Good agreement is shown. Fundamental limits are presented with the aid of simulation and measurements. Based on these results, implications on the next-generation design are discussed. [ABSTRACT FROM AUTHOR]

The French Alternative Energies and Atomic Energy Commission (CEA) and National Radioactive Waste Management Agency (ANDRA) are conducting an R&D program to improve the characterization of long-lived and medium-activity (LL-MA) radioactive waste packages with analytical methods and with non-destructive nuclear measurements. This paper discusses fast neutron interrogation with the associated particle technique (APT), which provides 3D information about the waste material composition. The characterization of volume elements filled with iron, water, aluminium and PVC in bituminized and fibre concrete LL-MA waste packages has been investigated with MCNP refid="ref1"/ and MODAR data analysis software refid="ref2"/ . APT provides useful information about major elements present in the volumes of interest. However, neutron scattering (especially on hydrogen nuclei) spreads the tagged neutron beam out of the targeted volume towards surrounding materials, reducing spatial selectivity. Simulation shows that targets smaller than 1 L can be characterized up to the half-radius of a 225 L bituminized drum, the matrix of which is very rich in hydrogen. Deeper characterization in concrete is possible but limited by counting statistics due to photon attenuation in this dense matrix and, unless large inspection volumes are considered, by the lack of spatial selectivity of the tagged neutron beam due to neutron scattering. [ABSTRACT FROM AUTHOR]

The purpose of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor, http://www.uncoss-project.org) is to develop a neutron-based underwater explosive sensor to detect unexploded ordnance lying on the sea bottom. The Associated Particle Technique is used to focus the inspection on a suspicious object located by optical and electromagnetic sensors and to determine if there is an explosive charge inside. This paper presents the data acquisition electronics and data analysis software which have been developed for this project. A field programmable gate array that digitizes and processes the signal allows to perform precise time-of-flight and gamma-ray energy measurements. The gamma-ray spectra are unfolded into pure elemental count proportions, mainly C, N, O, Fe, Al, Si, and Ca. The C, N, and O count fractions are converted into chemical proportions, taking into account the gamma-ray production cross sections, as well as neutron and photon attenuation in the different shields between the ROV (Remotely Operated Vehicle) and the explosive, such as the explosive iron shell, seawater, and ROV envelop. A two-dimensional (2D) barycentic representation of the C, N, and O proportions is built from their chemical ratios, and a 2D likelihood map is built from the associated statistical and systematic uncertainties. The threat level is evaluated from the best matching materials of a database including explosives. [ABSTRACT FROM AUTHOR]

Abstract: The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) uses 14MeV neutrons produced by the 3H(d,n)4H fusion reaction to detect explosives and narcotics in cargo containers. Reactions induced by fast neutrons produce gamma rays, which are detected in coincidence with the associated alpha particle to determine the neutron direction. In addition, the neutron path length is obtained from a time-of-flight measurement, thus allowing the origin of the gamma rays inside the container to be determined. Information concerning the chemical composition of the target material is obtained from the analysis of the energy spectrum. The carbon, oxygen, and nitrogen relative count contributions must be converted to chemical proportions to distinguish illicit and benign organic materials. An extensive set of conversion factors based on Monte Carlo numerical simulations has been calculated, taking into account neutron slowing down and photon attenuation in the cargo materials. An experimental validation of the method is presented by comparing the measured chemical fractions of known materials, in the form of bare samples or hidden in a cargo container, to their real chemical composition. Examples of application to real cargo containers are also reported, as well as simulated data with explosives and illicit drugs. [Copyright &y& Elsevier]

Abstract: Gamma-ray spectra produced in carbon, nitrogen, oxygen, sodium, aluminium, silicon, chlorine, calcium, chromium, iron, nickel, copper, zinc, and lead by 14MeV tagged neutrons have been collected with NaI(Tl) detectors of the EURITRACK system, which low-energy threshold has been reduced to 0.6MeV to detect gamma rays of major elements like iron. The spectra have been compared with Monte Carlo simulations to check the tabulated gamma-ray production data. A quantitative approach to subtract the scattered neutron background is also reported. [Copyright &y& Elsevier]

Tagged neutron inspection system was used for the underwater detection of explosives. Neutrons were produced in the d+t nuclear reaction with API 120 sealed tube neutron generator. Five kilograms of TNT explosive were measured in a pool filled with water. Measurements were done in target in, target out configuration. Also, a sandwich made of 6 mm thick iron plates with explosive placed between two layers of sea sediments was measured under the same conditions. Sediments were collected in the Adriatic Sea. Measurements were repeated with TNT explosive replaced by rocks of similar size and shape. Neutron tube was rotated in order to find the position of explosive (rocks) in the sandwich. It was found that TNT can be detected underwater and that is possible to distinguish TNT from the sea rocks placed between 6 mm thick iron plates or between layers of sediments by their ratios of carbon and oxygen. [ABSTRACT FROM AUTHOR]

Abstract: In the frame of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor), whose aim is to develop a neutron-based explosive detection system to identify unexploded ordnance (UXO) lying on the sea bottom, the choice of the gamma-ray detector is essential to reach the optimal performances. This paper presents comparative tests between the two candidates: NaI(Tl) and LaBr3(Ce) detectors, in favour to the 3in.×3in. LaBr3(Ce); thus, confirming the choice previously performed by numerical simulation because of its higher fast timing properties, spectral resolution, and efficiency per volume unit. The gamma-ray spectra produced by 14MeV tagged neutron beams on the elements of interest (C, O, N, Al, Fe, Si, and Ca) have also been recorded with this detector in order to unfold the spectrum of the interrogated object into elementary contributions. A qualitative comparison with the gamma-ray spectra simulated with the MCNPX computer code and the ENDFB/VII.0 nuclear library has also been performed to validate the numerical model. An additional quantitative validation has been performed with an explosive-like material (ammonium acetate). [ABSTRACT FROM AUTHOR]

The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) inspection system uses 14 MeV neutrons produced by the D(T,n\,\alpha) reaction to detect explosives in cargo containers. Reactions induced by fast neutrons inside the container produce gamma rays, which are detected in coincidence with the associated alpha particle, the detection of which allows the neutron direction to be determined. The neutron path length is obtained from a neutron time-of-flight measurement, thus allowing the origin of the gamma rays inside the container to be determined, while the chemical composition of the target material is correlated with their energy spectrum. Gamma-ray spectra have been collected with the inspection portal equipped with large volume NaI (Tl) detectors, in order to build a database of signatures for various elements (C, O, N, Fe, Pb, Al, Na, Si, Cl, Cu, Zn) with a low energy threshold of 0.6 MeV. The spectra are compared with previous ones, which were acquired with a 1.35 MeV threshold. The new library is currently being tested to unfold the energy spectra of transported goods into elemental contributions. Results are compared with data processed with the old 1.35 MeV threshold database, thus illustrating the improvement for material identification. [ABSTRACT FROM PUBLISHER]

Abstract: The elemental characterization of materials constituting radioactive waste is of great importance for the management of storage and repository facilities. To complement the information brought by gamma or X-ray imaging, the performance of a fast neutron interrogation system based on the associated particle technique (APT) has been investigated by using MCNP simulations and by performing proof-of-principle experiments. APT provides a 3D localisation of the emission of fast neutron induced gamma rays, whose spectroscopic analysis allows to identify the elements present in specific volumes of interest in the waste package. Monte Carlo calculations show that it is possible to identify materials enclosed behind the thick outer envelop of a ≈1m3 cemented waste drum, provided the excited nuclei emit gamma rays with a sufficient energy to limit photon attenuation. Neutron attenuation and scattering are also predominant effects that reduce the sensitivity and spatial selectivity of APT, but it is still possible to localise items in the waste by neutron time-of-flight and gamma-ray spectroscopy. Experimental tests confirm that the elemental characterization is possible across thick mortar slabs. [Copyright &y& Elsevier]

Abstract: The container scanning system based on the elemental analysis of suspect cargo by use of fast 14MeV neutrons with detection of associated alpha particle has been recently developed under the EU-FP6 “EURITRACK” project. The system is currently set-up in port of Rijeka, Croatia, to be tested and upgraded under the EU-JLS ERITR@C project. Here we present results of analysis performed on 152 screened containers selected by the Croatian Custom and detail descriptive statistical analysis of their shipping manifests. Statistics such as distribution functions of container types, type of packages, type of cargos and average cargo densities were obtained in order to establish the properties of standard cargo traffic. The analyses by using multivariate statistical approach that included principal component analysis (PCA) and between group analysis (BGA) have shown that cargo matrices can be classified as metallic (Fe, Al, Cu, Zn, Ni…), ceramic–glass (Si, O) and organic (C, O, N). In this paper the organic matrices have been analysed in more detail since they are identified as most difficult because of their potential interference with main elements contained in threat materials such as explosives or drugs. Density as a discriminating factor has been included for better recognition of different types of goods. [Copyright &y& Elsevier]

Abstract: The goal of the FP7 UNCOSS project (Underwater Coastal Sea Surveyor) is to develop a non destructive explosive detection system based on the associated particle technique, in view to improve the security of coastal area and naval infrastructures where violent conflicts took place. The end product of the project will be a prototype of a complete coastal survey system, including a neutron-based sensor capable of confirming the presence of explosives on the sea bottom. A 3D analysis of prompt gamma rays induced by 14MeV neutrons will be performed to identify elements constituting common military explosives, such as C, N and O. This paper presents calculations performed with the MCNPX computer code to support the ongoing design studies performed by the UNCOSS collaboration. Detection efficiencies, time and energy resolutions of the possible gamma-ray detectors are compared, which show NaI(Tl) or LaBr3(Ce) scintillators will be suitable for this application. The effect of neutron attenuation and scattering in the seawater, influencing the counting statistics and signal-to-noise ratio, are also studied with calculated neutron time-of-flight and gamma-ray spectra for an underwater TNT target. [Copyright &y& Elsevier]

ZnO-based scintillators are particularly well suited for use as the associated particle detector in a deuterium-tritium (D-T) neutron generator. Application requirements include the exclusion of organic materials, outstanding timing resolution, and high radiation resistance. ZnO, ZnO:Ga, ZnO:In, ZnO:In,Li, and ZnO:Er,Li have demonstrated fast (sub-nanosecond) decay times with relatively low light yields. ZnO:Ga has been used in a powder form as the associated particle detector for a D-T neutron generator. Unfortunately, detectors using powders are difficult to assemble and the light yield from powders is less than satisfactory. Single-crystal ZnO of sufficient size has only recently become available. New applications for D-T neutron generators require better timing resolution and higher count rates than are currently available with associated particle detectors using YAP:Ce as the scintillator. Recent work suggests that ZnO-based scintillators can provide alpha-particle-excited light yields comparable to YAP:Ce scintillators. ZnO-based polycrystalline ceramic scintillators offer the advantages of high light yield, ease of fabrication, low cost, and robust mechanical properties. Precursor powders used in these studies include ZnO and ZnO:Ga powders synthesized using solution-phase, urea precipitation, and combustion synthesis techniques as well as ZnO powder from a commercial vendor. Precursor powders have been sintered using uniaxial hot, pressing and spark plasma sintering techniques. Photoluminescence measurements have confirmed that, for most samples, the emissions from these sintered bodies consist primarily of slow, visible emissions rather than the desired sub-nanosecond near-band-edge emissions. Subsequent hydrogen treatments have shown significant improvements in the luminescence characteristics of some ceramic bodies, while other samples have shown no change in luminescence. [ABSTRACT FROM AUTHOR]

As part of an ongoing investigation of the scintillation properties of zinc-oxide-(ZnO)-based scintillators, several melt-grown, ZnO single crystals have been characterized using alpha-particle excitation, infrared reflectance, and room temperature photoluminescence. The crystals, grown by Cermet, Inc., using an oxygen-pressurized melt-growth process, were doped with Group 1 elements (Li), Group 2 elements (Mg), Group 3 elements (Ga, In) and Lanthanides (Gd, Er, Tm). The goals of these studies are to better understand the scintillation mechanisms associated with various members of the ZnO scintillator family and to then use this knowledge to improve the radiation detection capabilities of ZnO-based scintillators. One application for which ZnO is particularly well suited as a scintillator is as the associated particle detector in a deuterium-tritium (D-T) neutron generator. Application requirements include the exclusion of organic mate- rials, outstanding timing resolution, and high radiation resistance. ZnO:Ga and ZnO:In have demonstrated fast (subnanosecond) decay times with relatively low light yields, and ZnO(Ga) has been used in a powder form as the associated particle detector for a D-T neutron generator. Four promising candidate materials, ZnO, ZnO:Ga, ZnO:In,Li, and ZnO:Er,Li, were identified in this study. These four samples demonstrated sub-nanosecond decay times and alpha-particle-excited-luminescence comparable to BC-400 fast plastic scintillator. The ZnO:Mg,Ga, ZnO:Gd, and ZnO:Li samples demonstrated appreciable slow (microsecond) decay components that would be incompatible with high-counting-rate applications. [ABSTRACT FROM AUTHOR]

Abstract: The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) inspection system has been designed to complement X-ray scanners in the detection of explosives and other illicit materials hidden in cargo containers. The containers are interrogated by a 14-MeV tagged neutron beam at any suspect position in the X-ray image. Interrogation of a specific volume element with tagged neutrons yields information about the chemical composition of the material. Implementation and performance tests of the EURITRACK system in the Port of Rijeka in Croatia are described. Cargo container inspection results are reported and discussed. [Copyright &y& Elsevier]

Abstract: The EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) inspection system uses 14MeV neutrons produced by the D(T,n α) reaction to detect explosives in cargo containers. Fast-neutron-induced reactions inside the container produce gamma rays, which are detected in coincidence with the associated alpha particle. The definition of the neutron path and the time-of-flight measurement allow positioning the source of the gamma ray inside the container, while the chemical composition of the target material is correlated with the energy spectrum of the coincident gamma rays. However, in case of dense cargo, neutron moderation and photon attenuation inside the container make difficult the reconstruction of the material composition from the measured gamma-ray energy spectrum. An analytical method has been developed and validated against experimental data, which allows obtaining the chemical carbon-to-oxygen and carbon-to-nitrogen ratios of the inspected items from the gamma-ray energy spectra. The principle of the method is presented along with validation tests. [Copyright &y& Elsevier]

Abstract: The EURopean Illicit TRAfficing Countermeasures Kit (EURITRACK) Front-End and Data Acquisition System is a compact set of VME boards interfaced with a standard PC. The system is part of a cargo container inspection portal based on the tagged neutrons technique. The front-end processes all detector signals and checks coincidences between any of the 64 pixels of the alpha particle detector and any gamma-ray signals in 22 NaI(Tl) scintillators. The system is capable of handling the data flow at neutron flux up to the portal limiting value of 108 neutrons/second. Some typical applications are presented. [Copyright &y& Elsevier]

Abstract: The EURopean Illicit TRAfficing Countermeasures Kit (EURITRACK) project is part of the 6th European Union Framework Program. It aims at developing a Tagged Neutron Inspection System (TNIS) to detect illicit materials, such as explosives and narcotics, in cargo containers. Fast neutron induced reactions produce specific gamma-rays used to determine the chemical composition of the inspected material. The associated particle technique is employed to precisely locate the interaction points of the neutrons. A new deuterium–tritium neutron generator has been developed, including a pixelized alpha particle detector. The TNIS also comprises high-efficiency fast neutron and gamma-ray detectors, a dedicated front-end electronics and an integrated software to entirely drive the system and automatically process the data. Most components have been integrated during last months at Institute Ruder Boskovic, in Zagreb, Croatia. An overview of the TNIS and of its preliminary performances is presented. [Copyright &y& Elsevier]