14N-NQR based device for detection of explosives in landmines

Abstract A short survey of technologies proposed and implemented so far for landmine detection is given. A laboratory prototype device intended for RDX and HMX explosive detection in landmines by means of 14 N-NQR (nuclear quadrupole resonance) spectroscopy is described. This NQR based landmine detector is essentially a fully automated and computer controlled FT-NQR spectrometer equipped with a planar r.f. measure coil. The temperature dependencies of NQR frequencies ν Q ( T ) in RDX and HMX in the temperature range of practical interest for explosive detection were measured. Final testing of the device has been carried out on samples of sodium nitrite (NaNO 2 ) which had to be used to simulate real landmines in order to obey the safety regulations. Experimentally optimized SORC (strong off-resonance comb) multi-pulse sequence were used for optimum NQR signal. The time of detection was 30 and 90 s for sodium nitrite simulants buried in depths of 7 and 10 cm under ground, respectively. The sensitivity of detection was limited mostly by the external r.f. interferences, both man-made and naturally occurring, which enter the NQR detection system through the unshielded measure coil. Possible means to circumvent these limitations are also discussed.

[1]  Suits,et al.  Noise-immune coil for unshielded magnetic resonance measurements , 1998, Journal of magnetic resonance.

[2]  S. M. Caulder,et al.  Factors affecting the NQR line width in nitramine explosives , 2004 .

[3]  Joel B. Miller,et al.  Narcotics and explosives detection by 14N pure nuclear quadrupole resonance , 1994, Other Conferences.

[4]  Methods for optimizing the detection of HMX by nuclear quadrupole resonance , 2004 .

[5]  R. Blinc,et al.  Nuclear quadrupole double resonance techniques for the detection of explosives and drugs , 2004 .

[6]  G. N. Shilstone,et al.  Nuclear quadrupole resonance of explosives: Simultaneous detection of RDX and PETN in semtex , 2004 .

[7]  C. L. Ruthroff.  Some Broad-Band Transformers , 1959, Proceedings of the IRE.

[8]  D. Loganathan,et al.  The quadrupole resonance properties of nondetonable explosive formulations for land mine detection machine calibration and testing , 2004 .

[9]  T. N. Rudakov,et al.  Multipulse sequences for explosives detection by NQR under conditions of magnetoacoustic and piezoelectric ringing , 2004 .

[10]  Modified multipulse technique for the effective detection of pure nuclear quadrupole resonance , 2004 .

[11]  V. S. Grechishkin.  NQR device for detecting plastic explosives, mines, and drugs , 1992 .

[12]  DESIGN NOTE: A low-frequency instrument for remote nuclear quadrupole resonance experiments , 1997 .

[13]  V. Anferov,et al.  Pulsed spectrometer for nuclear quadrupole resonance for remote detection of nitrogen in explosives , 2000 .

[14]  A. N. Garroway,et al.  Super-QDetection of Transient Magnetic Resonance Signals , 1998 .

[15]  B. H. Suits,et al.  The noise immunity of gradiometer coils for14N NQR land mine detection: Practical limitations , 2004 .

[16]  H. Bayer.  Zur Theorie der Spin-Gitterrelaxation in Molekülkristallen , 1951 .

[17]  A. N. Garroway,et al.  Surface and gradiometer coils near a conducting body: the lift-off effect. , 1998, Journal of magnetic resonance.

[18]  T. N. Rudakov,et al.  The use of multi-pulse nuclear quadrupole resonance techniques for the detection of explosives containing RDX , 1997 .