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.
Preface.- Fundamentals of Pulsed Nitrogen-14 Quadrupole Resonance; D. Canet, M. Ferrari.- 14N NQR Detection of Explosives with Hybrid Sensors; M. Pannetier-Lecoeur et al.- Polarization Enhanced NQR Detection at Low Frequencies; J. Luznik et al.- Efficient Excitation and Ringing Suppression in Nuclear Quadrupole Resonance; J.B. Miller et al.- Detection of Concealed Liquid Explosives and Illicit Drugs in Unopened Bottles; S. Kumar, P.J. Prado.- Prospectives and Limitations of NQR Signal Enhancement by Polarisation Transfer; A.F. Privalov et al.- Modeling of QR Sensors for Optimized Explosives Detection; H. Robert et al.- Detection of Explosives by NQR Method: Main Aspects for Transport Security; T.N. Rudakov.- Double Resonance Detection of (Mainly Nitrogen) NQR Frequencies in Explosives and Drugs; J. Seliger, V. Zagar.- Signal Processing Methods in NQR; V.S. Grechishkin et al.- 14N Nuclear Quadrupole Resonance Signals in Paranitrotoluene and Trinitrotoluene. Spin-Lock Spin-Echo off-resonance Effects; A. Gregorovic et al.- Identification of Liquids Encountered in Carry-on-Luggage by Mobile NMR; J. Mauler et al.- The Two-Frequency Multipulse Sequence in Nuclear Quadrupole Resonance of N-14 Nuclei; G.V. Mozzhukhin et al.- The Detection of Industrial Explosives by the Quadrupole Resonance Method: Some Aspects of the Detection of Ammonium Nitrate and Trinitrotoluene; G.V. Mozzhukhin et al.- Development of Electric Field NMR Signal Acquisition System; R.J. Prance et al.- Berry’s Phase in NQR of Powders; N. Sinyavsky et al.- Contribution of Copper NQR Spectroscopy to the Geological Studies of Complex Sulfides and Oxides; R.R. Gainov et al.- Index.-
