Nuclear quadrupole resonance (NQR) a highly promising new technique for bulk explosives detection: relatively inexpensive, more compact than NMR, but with considerable selectivity. Since the NQR frequency is insensitive to long-range variations in composition, mixing explosives with other materials, such as the plasticizers in plastic explosives, makes no difference. The NQR signal strength varies linearly with the amount of explosive, and is independent of its distribution within the volume monitored. NQR spots explosive types in configurations missed by the X-ray imaging method. But if NQR is so good, why it is not used everywhere? Its main limitation is the low signal-to-noise ratio, particularly with the radio-frequency interference that exists in a field environment, NQR polarization being much weaker than that from an external magnetic field. The distinctive signatures are there, but are difficult to extract from the noise. In addition, the high selectivity is partly a disadvantage, as it is hard to build a multichannel system necessary to cover a wide range of target substances. Moreover, substances fully screened by metallic enclosures, etc. are difficult to detect. A workshop was held at St Petersburg in July 2008 in an attempt to solve these problems and make NQR the universal technique for the detection of bombs regardless of type. This book presents the essentials of the papers given there.

Detection of concealed explosives is a notoriously difficult problem, and many different approaches have been proposed to solve this problem. Nuclear quadrupole resonance (NQR) is unique in many ways. It operates in a safe AM radio frequency range, and it can remotely detect unique “fingerprint” (NQR spectrum) of many explosives, such as TNT or RDX. As such, the detection of target does not depend on the shape or material of the container, or the presence of metallic object such as triggers etc. Spectra of chemically similar compounds differ enough that their presence never causes interference or false alarms. Unfortunately, widespread use is prevented due to low sensitivity, radiofrequency interference from the noisy environment, and inability to detect liquid explosives. This book presents current state of the art of the attempts to overcome NQR sensitivity problem, either by increasing the strengths of signals generated, or by increasing the specificity of the technique through a better understanding of the factors that affect the quadrupolar parameters of specific explosives. The use of these specific quadrupolar parameters is demonstrated on signal processing techniques that can detect weak signals, which are hidden in a noisy background. The problem of differentiation of liquid explosives and benign liquids in closed containers is approached by measurements of different nuclear magnetic resonance (NMR) parameters. As shown, a couple of solutions has reached a prototype stage and could find their use in a near future.

This book is about improving prohibited substances detection using the nuclear quadrupole resonance (NQR) technique at security checkpoints. The book proposes multiple signal processing and analysis techniques for improving detection of dangerous or contraband substances, such as explosives, narcotics, or toxic substances. Also, several hardware solutions are described and implemented in a custom-designed NQR spectrometer. A new approach to NQR signal detection is introduced using artificial intelligence/deep learning techniques. The book will be useful for for researchers and practitioners in the areas of electrical engineering, signal processing and analysis, applied spectroscopy, as well as for security or laboratory equipment manufacturers.

Existing and Potential Standoff Explosives Detection Techniques examines the scientific techniques currently used as the basis for explosives detection and determines whether other techniques might provide promising research avenues with possible pathways to new detection protocols. This report describe the characteristics of explosives, bombs, and their components that are or might be used to provide a signature for exploitation in detection technology; considers scientific techniques for exploiting these characteristics to detect explosives and explosive devices; discusses the potential for integrating such techniques into detection systems that would have sufficient sensitivity without an unacceptable false-positive rate; and proposes areas for research that might be expected to yield significant advances in practical explosives and bomb detection technology in the near, mid, and long term.

This volume presents selected contributions from the “Advanced Research Workshop on Explosives Detection” hosted by the Department of Information Engineering of the University of Florence, Italy in 2018. The main goal of the workshop was to find out how Science for Peace and Security projects in the field of Explosives Detection contribute to the development and/or refinement of scientific and technical knowledge and competencies. The findings of the workshop, presented in the last section of the book, determine future actions and direction of the SPS Programme in the field of explosives detection and management.The NATO Science for Peace and Security (SPS) Programme, promotes dialogue and practical cooperation between NATO member states and partner nations based on scientific research, technological innovation and knowledge exchange. Several initiatives were launched in the field of explosive detection and clearance, as part of NATO’s enhanced role in the international fight against terrorism. Experts and scientists from NATO members and partner countries have been brought together in multi-year projects, within the framework of the SPS Programme, to cooperate in the scientific research in explosive detection field, developing new technologies and methods to be implemented in order to detect explosive substances in different contexts.

The use of explosives in terror attacks, including improvised ones, presents an ongoing threat which requires the development of techniques for detecting a larger variety of explosives, faster detection, and with lower rates of false alarms. Counterterrorist detection techniques of explosives [...] covers the most successful techniques for explosives detection at present. This completely revised volume describes the most updated research findings, which will be used in the next generation of explosives detection technologies. New editors Drs. Avi Cagan and Jimmie Oxley have assembled in one volume a series of detection technologies of explosives, written by a group of scientists who are experts in each of these technologies. The book helps researchers to compare the advantages and disadvantages of all available methods in detecting explosives and, in effect, allow them to choose the correct instrumental screening technology according to the nature of the sample.