The Problem of Military TNT in NQR Mine Detector
01 Jan 2002-pp 217-225
TL;DR: In this paper, the quadrupole moment of a nucleus interacts with the electric-field gradient of the surrounding molecule and crystal, and thus the energy-level differences are molecule- and crystal-specific.
Abstract: One of the most promising methods of demining is nuclear-quadrupole resonance (NQR) with nitrogen-14, which is contained in practically all mine explosives. In NQR the quadrupole moment of a nucleus interacts with the electric-field gradient of the surrounding molecule and crystal, and thus the energy-level differences are molecule- and crystal-specific. In pure NQR, no external magnetic field is needed. One may, however, combine nuclear magnetic resonance (NMR), e.g., of protons, with NQR to achieve selective excitation or better signal; in this case, a strong magnetic field has to be switched on and off.
Citations
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01 Jan 2005
TL;DR: In this paper, the authors demonstrate that the broadening of a signal below noise and shift of its frequency detuning interfere with reliable signal detection for SNR ≤ 0.05.
Abstract: Principles of message transfer in telecommunication systems are considered when a wide transmission band is required, which can result in tuning away from the transmitting station if the signal-to-noise ratio (SNR) is insufficiently high. Based on a solution of the Fokker−Planck−Kolmogorov equation, it is demonstrated that a signal below noise is broadened 20 times for SNR = 0.05. This makes signal accumulation difficult. The matrix pencil method of information theory is used to demonstrate that the broadening of a signal below noise and shift of its frequency detuning interfere with reliable signal detection for SNR ≤ 0.05. An analog of the Bohr complementarity principle is used to analyze the NQR detector. In addition, performance of the NQR-mine detector used to clear of mines territories of former military actions is examined.
8 citations
TL;DR: In this paper, the authors demonstrate that the broadening of a signal below noise and shift of its frequency detuning interfere with reliable signal detection for SNR ≤ 0.05.
Abstract: Principles of message transfer in telecommunication systems are considered when a wide transmission band is required, which can result in tuning away from the transmitting station if the signal-to-noise ratio (SNR) is insufficiently high. Based on a solution of the Fokker-Planck-Kolmogorov equation, it is demonstrated that a signal below noise is broadened 20 times for SNR = 0.05. This makes signal accumulation difficult. The matrix pencil method of information theory is used to demonstrate that the broadening of a signal below noise and shift of its frequency detuning interfere with reliable signal detection for SNR ≤ 0.05. An analog of the Bohr complementarity principle is used to analyze the NQR detector. In addition, performance of the NQR-mine detector used to clear of mines territories of former military actions is examined.
6 citations
01 Jan 2014
4 citations
Cites background from "The Problem of Military TNT in NQR ..."
...For example, impurities are known to e↵ect NQR characteristics such as signal intensity, T ⇤ 2 , and line-width [8,40,68,89], and small impurities in TNT are known to reduce the signal by a factor of ten [27]....
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...In field applications, it is common for the NQR signal to be about the same intensity as the transceiver coil’s thermal noise, making the signal to noise ratio (SNR) very low [16,27,38]....
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...This is especially the case for materials with long T1 such as TNT since this increases the rest time necessary between successive measurements [24,27,36]....
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TL;DR: In this article, a small and inexpensive portable device developed for detecting landmines using NQR is presented, which uses a field-programmable gate array and low-impedance transmission and reception circuits that include a dual supply class-D power amplifier powered by conventional batteries to ensure sufficient magnetic field excitation for mine detection.
Abstract: Nuclear quadrupole resonance (NQR) technology is a promising approach to detect so-called “minimum metal” landmines, as it can look directly for their explosive content. Conventional commercially available NQR devices, however, are large and expensive, and they require a transmitter power amplifier with a power generator, which is not suitable for outdoor use and mass production. Here we present a small and inexpensive portable device developed for detecting landmines using NQR. The device uses a field-programmable gate array (FPGA) and low-impedance transmission and reception circuits that include a dual supply class-D power amplifier powered by conventional batteries to ensure sufficient magnetic field excitation for mine detection. The pulse width modulation signals that are fed into the power amplifier have been designed to protect the low impedance transmit-receive switch circuit from the high voltage. The system has been tested successfully in the laboratory with 100g of explosive RDX at a distance of 10cm from the antenna, corresponding to a plausible anti-personal (AP) mine scenario. Detection was achieved with a signal to noise ratio (SNR) ~2 in 2/3 of the time that a previous prototype required (120 sec). Moreover, the new device can detect RDX explosives with a measurement time and SNR comparable to mine detectors built with commercial-off-the-shelf (COTS) components, but at lower cost and smaller form factor.
3 citations
Cites background from "The Problem of Military TNT in NQR ..."
...Many types of landmines and plastic explosives are made of the high explosive RDX (C3H6N6O6) [1], [2]....
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TL;DR: In this article, the spectra of double nuclear quadrupole resonance of nitrogen-containing compounds are considered and a comparison is made of this technique with the cross-relaxation method.
Abstract: Remote detection of the spectra of double nuclear quadrupole resonance of nitrogen-containing compounds is considered. A comparison is made of this technique with the cross-relaxation method.
2 citations
References
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TL;DR: A novel detection–estimation scheme is introduced in order to analyze data from solid-state NMR experiments and others where the sensitivity is low and/or the data record is strongly damped or truncated, and holds great promise in effectively reducing truncation artifacts.
110 citations
TL;DR: In this paper, a NQR device was proposed to detect plastic explosives, mines, and drugs and discuss design considerations. But this device was not suitable for the detection of drugs.
Abstract: We describe a NQR device to detect plastic explosives, mines, and drugs and discuss design considerations
42 citations
TL;DR: In this article, NQR devices for detecting plastic explosives, mines and drugs are described, as well as their application in the detection of drugs and other contrabands, such as drugs.
Abstract: We describe NQR devices for detecting plastic explosives, mines and drugs.
17 citations
TL;DR: In this article, the two-frequency pulse response of a multilevel system in NQR is investigated and additional spin echo signals are shown to appear, which is of great value for the investigation of local fields in crystals.
Abstract: The two-frequency pulse response of a multilevel system in NQR is investigated. Additional spin echo signals are shown to appear. The application of the two-frequency spin echo method to some of the crystals is demonstrated. The method is of great value for the investigation of local fields in crystals.
9 citations
TL;DR: In this article, the relative intensities of NSR lines for spin 1 or 3/2 568 1.568 2.1 568 3.2 571 4.5
Abstract: I. Introduction 566 II. NSR energy levels and frequencies 568 1. Energy levels for resonating nuclei with spins 1 or 3/2 568 2. NSR energy levels for spin 5/2 571 III. Relative intensities of NSR lines 571 1. Relative intensities of Zeeman components in NQR 571 2. Generalized NSR equations 572 3. Relative intensities of NSR lines for spin 1 or 3/2 572 4. Relative intensities of NSR lines for spin 5/2 577 IV. Temperature dependence of the absorption frequencies and theory of nuclear spin-lattice relaxation 578 V. Experimental procedure 581 VI. Experimental values of the quadrupole interaction constants 582 Cited literature 587
9 citations