Magnetic quadrupole  


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 right. Electromagnets of similar conceptual design (called quadrupole magnets) are commonly used to focus beams of charged particles in particle accelerators and beam transport lines, a method known as strong focusing. The quadrupole-dipole intersect can be found by multiplying the spin of the unpaired nucleon by its parent atom. There are four steel pole tips, two opposing magnetic north poles and two opposing magnetic south poles. The steel is magnetized by a large electric current that flows in the coils of tubing wrapped around the poles.Changing magnetic quadrupole moments produces electromagnetic radiation

Explosives Detection with Nuclear Quadrupole Resonance
An emerging technology will help to uncover land mines and terrorist bombs
( a Joel B. Miller and Geoffrey A. Barrall reference  )




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 [1] 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.


Applying a pulse of the correct frequency υ flips the nuclear spin and induces an NQR signal in a pickup coil.  Quadrupolar Nucleus Slightly Aligned by the Electrostatic Interaction with the Valence Electrons


Nuclear quadrupole resonance
"NQR" redirects here. For the Tufts University tradition, see Naked Quad Run.
Nuclear quadrupole resonance spectroscopy or NQR is a chemical analysis technique related to nuclear magnetic resonance (NMR).
In NMR, nuclei with spin ≥ 1/2 have a magnetic dipole moment so that their energies are split by a magnetic field, allowing resonance absorption of energy related to the difference between the ground state energy and the excited state. In NQR, on the other hand, nuclei with spin ≥ 1 , such as 14N, 35Cl and 63Cu, also have an electric quadrupole moment so that their energies are split by an electric field gradient, created by the electronic bonds in the local environment.
Since unlike NMR, NQR is done in an environment without a static (or DC) magnetic field, it is sometimes called "zero field NMR". Many NQR transition frequencies depend strongly upon temperature.
Any nucleus with more than one unpaired nuclear particle (protons or neutrons) will have a charge distribution which results in an electric quadrupole moment. Allowed nuclear energy levels are shifted unequally due to the interaction of the nuclear charge with an electric field gradient supplied by the non-uniform distribution electron density (e.g. from bonding electrons) and/or surrounding ions.
The NQR effect results when transitions are induced between these nuclear levels by an externally applied radio frequency (RF) magnetic field. The technique is very sensitive to the nature and symmetry of the bonding around the nucleus. The energy level shifts are much larger than the chemical shifts measured in NMR. Due to symmetry, the shifts become averaged to zero in the liquid phase, so NQR spectra can only be measured for solids.
There are several research groups around the world currently working on ways to use NQR to detect explosives. Units designed to detect landmines and explosives concealed in luggage have been tested.
A detection system consists of a radio frequency (RF) power source, a coil to produce the magnetic excitation field and a detector circuit which monitors for a RF NQR response coming from the explosive component of the object.
Another practical use for NQR is measuring the water/gas/oil coming out of an oil well in realtime.
This particular technique allows local or remote monitoring of the extraction process, calculation of the well's remaining capacity and the water/detergents ratio the input pump must send to efficiently extract oil.  

The strong temperature dependence of NQR's frequency allows to make a precise temperature sensor with resolution 10-4 °C.

Appendix K: Nuclear quadrupole resonance, by Allen N. Garroway, Naval Research Laboratory. In Jacqueline MacDonald, J. R. Lockwood: Alternatives for Landmine Detection. Report MR-1608, Rand Corporation, 2003.

Leigh, James R. (1988). Temperature measurement & control. London: Peter Peregrinus Ltd.. p. 48. ISBN 0 86341 111 8.


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

October 1992.

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

May 1994..

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.