All known magnetic sources give dipole fields. However, to make a magnetic quadrupole it is possible to place four identical bar magnets perpendicular to each other such that the north pole of one is next to the south of the other. Such a configuration cancels the dipole moment and gives a quadrupole moment, and its field will decrease at large distances faster than that of a dipole.
An example of a magnetic
quadrupole, involving permanent magnets, is depicted on the
Allen N. Garroway, Naval Research Laboratory1
The Polymer Diagnostics Section (Code 6122) of the U.S. Naval Research Laboratory (NRL) has expertise in solid state nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), and nuclear quadrupole resonance (NQR). In 1983, NRL established an interagency agreement with the Federal Aviation Administration (FAA) to advise the FAA on NMR methods to detect explosives. We were aware of earlier work  on the use of NQR for explosives detection, and in 1987 we initiated a research program at NRL to explore NQR, with initial support of the FAA and Technical Support
Working Group (Department of Defense). NQR explosives detection technologies, including methods applicable for landmine detection, have been developed and patented by NRL and have been licensed by the U.S. Navy to Quantum Magnetics (San Diego, Calif.), a subsidiary of InVision Technologies Inc.
The strong temperature dependence of
NQR's frequency allows to make a precise temperature
see also :
1. "Nuclear Quadrupole Resonance", T.P. Das and E.L. Hahn, Chapter in Solid State
Physics, Suppl.l, Academic Press, New York, 1958.
2. Abragam, The Principles of Nuclear Magnetism, Clarendon Press, 1961
3. "Steady State Free Precession in Nuclear Magnetic Resonance," H.Y. Carr, Physical
Review, 112, 1693-1701, 1958.
4. "Nitrogen-14 NQR Study of Energetic Materials," R.A.Marino, R.F. Connors, and
L.Leonard (Block Engineering), Final Report to on U.S.Army Research Office
Contract DAAG29 79 C 0025, September 1982.
5. "Multiple Spin Echoes in Pure Quadrupole Resonance," R.A. Marino and S.M.
Klainer, Journal of Chemical Physics, 67,3388-3389, 1977.
6. "Explosives Detection by Pure 14N NQR", A.N. Garroway, J.B. Miller and M.L.
Buess, Proceedings of the 1st International Symposium on Explosive Detection
Technology, November 13-15,1991, Atlantic City, USA.
7. "Pulsed Spin Locking in Nuclear Quadrupole Resonance of 14N," D.Ya. Osokin,
Soviet Physics. JETP, 57(1), 69-71, 1983.
8. "Experimental Investigations of the Strong Off-Resonant Comb (SORC) Pulse
Sequence in 14N NQR," S.S.Kim, J.R.P.Jayakody, and R.A. Marino, Zeitshrift fur
Naturforschung, 47a, 415-420, 1992.
9. "Pulsed Fourier Transform NQR of 14N with a DC SQUID," M.D.Hurlimann,
C.H.Pennington, N.Q.Fan, J.Clarke, A.Pines, and E.L.Hahn, Physical Review Letters,
69, 684-687, 1992.
10. "SQUID Technology for Improved NMR/NQR Measurements Below 1MHz,"
Quantum Magnetics, Final Report on NSF Award 9160966, September 29, 1992.
11. "Librational Motion of Hexahydro-l,3,5-trinitro-s-triazine Based on the Temperature
Dependence of Nitrogen-14 Nuclear Quadrupole Resonance Spectra: The
Relationship to Condensed-Phase Thermal Decomposition," R.J. Karpowicz and
T.B.Brill, Journal of Physical Chemistry, 87, 2109-2112, 1983.
12. "Detection of Explosives by Nuclear Quadrupole Resonance (NQR)." A.N.
Garroway, J.B. Miller, J.P. Yesinowski, and M.L. Buess, Naval Research Laboratory,Final Report on Contract NEODTC N0464A92WR04515, FAA DTFA03-83-A-
00322, March 26 1993.
13. "Electronic Effects and Molecular Motion in ß-Octahydro-l,3,5,7-tetranitro-l,3,5,7- tetrazocine Based on 14N Nuclear Quadrupole Resonance Spectroscopy,"
A.G.Landers, T.B.Brill, and R.A. Marino, Journal of Physical Chemistry, 85, 2618- 2643, 1981.
14. "Nitrogen-14 Nuclear Quadrupole Resonance of Substituted Nitrobenzenes," S.N.Subbarao, E.G. Sauer, and P.J.Bray, Physics Letters, 42A, 461, 1973.
15. "Nitrogen-14 Nuclear Quadrupole Resonance Study of Substituted Nitrobenzenes,"S.N. Subbarao and P.J.Bray, Journal of Chemical Physics, 67(9), 3947-55, 1977.
16. "14N and 39K Nuclear Quadrupole Coupling in KN03," T.J. Barstow and S.N.
Stewart, Zeitschrift fur Naturforschung, 45a, 459-463, 1990.
17. "14N NQR Study of the Structural Phase Transitions in NH4NO3," J.Seliger, V.Zagar,
and RBlinc, Zeitschrift fur Physik B, Condensed Matter, 77, 439-443, 1989.
18. Private communication, R.A.Marino, Hunter College, CUNY, NY, September 1994.
19. "Nuclear Magnetic Resonance of 14N and 35C1 in Ammonium Perchlorate," T.J.
Barstow and S.N. Stewart, Journal of Physics: Condensed Matter, 1,4649-4657,
20. "Nitrogen-14 and Nitrogen-15 Wide-Line NMR Studies of Nitrocellulose," R.A.
Marino, Final Technical Report for Task 7-09, Department of Army, 30 October
21. "Detection of NQR in Explosives," V.S. Grechishkin, Russian Journal of Physics,
35(7), English Pages 637-640, 1992. Translation of Izvestiya Vysshikh Uchebnyykh
Zavedenii, Fizika, No.7, pp.62-65, July 1992.
22. Private Communication, T.J. Rayner, July 1994.
23. "Engineering Design Handbook: Explosives Series, Properties of Explosives of
Military Interest," U.S. Army Materiel Command, January 1971.
Other Relevant QR Papers Not Referenced
1. "Detection of Explosives and Narcotics by Low Power Large Sample Volume
Nuclear Quadrupole Resonance (NQR)", M.L. Buess, A.N. Garroway and J.B. Miller,
U.S. Patent 5206592..
2. "Detection of Explosives by Nuclear Quadrupole Resonance," M.L. Buess, J.B.
Miller, and A.N. Garroway, U.S. Patent 5233300.
3. "A Means for Removing Effects of Acoustic Ringing and Reducing the Temperature
Effects in the Detection of Explosives and Narcotics by Nuclear Quadrupole
Resonance," M.L. Buess, A.N. Garroway, and J.P. Yesinowski, Navy Case Number
74,325 (filed 30 Nov. 1992).
4. "Narcotics Detection using Nuclear Quadrupole Resonance," J. Shaw, Contraband
and Cargo Inspection Technology International Symposium, Washington D.C., 28-30
5. "A Search for NQR Signals in Heroin and Cocaine," R.A. Marino and J.R.P.
Jayakody, Final Technical Report on subcontract to Quantum Magnetics under US
Customs contract TC-91-031.
6. "NQR for Bomb Detection: Solution to the Plastics Problem ?" D. Noble, Analytical
Chemistry, 66 (5), 320A - 324A, March 1 1994.
7. "Explosives Detection by Nuclear Quadrupole Resonance (NQR)," A.N. Garroway,
M.L. Buess, J.P. Yesinowski, J.B.Miller, and R.A. Krauss, Report on results of
demonstration of prototype NQR explosives detector at FAA Technical Center in
8. "NQR Device for Detecting Plastic Explosives, Mines, and Drugs," V.S. Grechishkin,
Applied Physics, A55, 505-507, 1992.
9. "Short Range Remote NQR Measurments," T. Hirschfeld and S.M. Klainer, Journal
of Molecular Structure, 58, 63-77, 1980.
10. "A Pulsed NQR-FFT Spectrometer for Nitrogen-14," J.C.Harding, D.A.Wade, R.A.
Marino, E.G.Sauer, and S.M.Klainer, Journal of Magnetic Resonance, 36,21-33,
11. "New Methods of Nuclear Quadrupole Resonance," V.S. Grechishkin and N.Ja.
Sinjavsky, Zeitschrift fur Naturforschung, 45a, 559, 1990.