A review of conventional explosives detection using active neutron interrogation

Simulation of explosive detection based on APT-TOF for verifying nuclear warhead dismantlement

Authentication of the explosives in nuclear warheads is a key point for the global nuclear disarmament. In this paper, a detection method of the explosives in nuclear warheads based on API-TOF (associated α particle imaging - time of flight) is proposed. First, the basic principles and current research situation of API-TOF are introduced. Second, a numerical simulation platform of the detection method of the explosives in nuclear warheads based on API-TOF was established, and a numerical simulation study of the feasibility of this method was carried out. The research results show that, this method can detect the nuclides of ¹²C, ¹⁴N and ¹⁶O of the explosive in the nuclear warhead in 15 min, and reconstruct the carbon-oxygen number ratio and nitrogen-oxygen number ratio of the explosive accurately, and reconstruct the spatial distribution of the explosive nuclei with the explosive profile clearly discriminated in the reconstruction image. From the simulation results, the detection method of the explosive in the nuclear warhead based on API-TOF is confirmed.

Fingerprinting of Nitroaromatic Explosives Realized by Aphen-functionalized Titanium Dioxide

Developing sensing materials for military explosives and improvised explosive precursors is of great significance to maintaining homeland security. 5-Nitro-1,10-phenanthroline (Aphen)-modified TiO₂ nanospheres are prepared though coordination interactions, which broaden the absorption band edge of TiO₂ and shift it to the visible region. A sensor array based on an individual TiO₂/Aphen sensor is constructed by regulating the excitation wavelength (365 nm, 450 nm, 550 nm). TiO₂/Aphen shows significant response to nitroaromatic explosives since the Aphen capped on the surface of TiO₂ can chemically recognize and absorb nitroaromatic explosives by the formation of the corresponding Meisenheimer complex. The photocatalytic mechanism is proved to be the primary sensing mechanism after anchoring nitroaromatic explosives to TiO₂. The fingerprint patterns obtained by combining kinetics and thermodynamics validated that the single TiO₂/Aphen sensor can identify at least six nitroaromatic explosives and improvised explosives within 8 s and the biggest response reaches 80%. Furthermore, the TiO₂/Aphen may allow the contactless detection of various explosives, which is of great significance to maintaining homeland security.

Optimization of Moderator Design for Explosive Detection by Thermal Neutron Activation Using a Genetic Algorithm

An optimal design analysis is carried out for an explosives’ detection system (EDS) based on thermal neutron activation (TNA) of a sample under investigation. The objective of this work is to use a genetic algorithm (GA) to obtain the optimized moderator design that would yield the “best” signal in a detection system. In a preliminary analysis, a full Monte Carlo (MC) simulation is carried out to estimate the effectiveness of various moderators, namely, water, graphite, and beryllium with respect to radiative capture (n,γ) reactions in a sample under investigation. Since MC simulation is computationally “expensive,” it is generally not used for random-search-based optimization analysis. Thus, more efficient methods are required for the design of optimal nuclear systems, where neutron transport is accurately modeled and iteratively solved for estimating the effect of independent design parameters. This paper proposes a computational scheme in which GA is coupled with the two-group neutron diffusion equation (DE) for carrying out an optimization analysis. The coupled GA-DE optimization scheme is demonstrated for obtaining the optimal moderator design. It is found that with considerably less computational effort than in an elaborate MC computation, the GA-DE approach can be used for the optimal design of detection systems.

Advances in explosives analysis--part II: photon and neutron methods

The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245-246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. The review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers, electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. This part, Part II, will review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.