QUADRUPOLE RESONANCE USING NARROWBAND PROBES AND CONTINUOUS WAVE EXCITATION

• US 20080036462A1
• Filed: 02/27/2007
• Published: 02/14/2008
• Est. Priority Date: 02/27/2006
• Status: Active Grant

• Current Assignee: Penn State Research Foundation (Pennsylvania State University)
• Original Assignee: Penn State Research Foundation (Pennsylvania State University)
• Inventors: Schiano, Jeffrey
• Granted Patent: US 7,511,496 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/34023 Superconducting RF coils
• CPC Class Codes: G01R 33/34053 Solenoid coils; Toroidal coils
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil
• CPC Class Codes: G01R 33/3671 involving modulation of the quality factor of the RF coil G01R33/3642 takes precedence
• CPC Class Codes: G01R 33/441 Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging

Abstract

The use of a superconducting resonator with continuous-wave (CW) excitation allows low-noise quadrupole resonance (QR) detection without the need for a lock-in amplifier. This allows detection times to be greatly reduced. Hence, for the first time, a CW QR spectrometer using a superconducting resonator can be used in a portable device, such as a hand-held wand for detecting explosives.

Claims

1. An apparatus to assist detection of an analyte within a sample volume using nuclear quadrupole resonance (QR), the analyte having a QR response at an expected response frequency, the apparatus comprising:

a continuous wave exciter;

a superconducting resonator having a resonance frequency; and

a receiver circuit, receiving a signal from the superconducting resonator, the receiver circuit not including a lock-in amplifier.

2. The apparatus of claim 1, further including an excitation coil separate from the superconducting resonator, the continuous wave exciter energizing the excitation coil;

the superconducting resonator operating as a receiver coil.

3. The apparatus of claim 1, wherein the continuous wave exciter comprises an CW oscillator and a non-superconducting coupler coil.

4. The apparatus of claim 3, wherein the resonance frequency of the superconducting resonator is adjustable using an array of switched capacitors in a coupled resonator.

5. The apparatus of claim 4, wherein the oscillation frequency of the oscillator is adjustable using a second array of switched capacitors, the oscillation frequency of the oscillator being correlated with the resonance frequency.

6. The apparatus of claim 1, further comprising an electronic module, the electronic module controlling the resonance frequency of the superconducting resonator.

7. The apparatus of claim 1, wherein the apparatus is in the form of a portable device.

8. A method of detecting an analyte within a search volume, the search volume including a volume in transit using commercial transportation, the method comprising:

exciting the search volume using a continuous-wave oscillator;

detecting a QR response signal from the search volume using a superconducting resonator, the superconducting resonator having a resonance frequency;

adjusting the resonance frequency of the superconducting resonator so as to obtain a QR spectrum of the search volume; and

detecting the analyte within the search volume using a QR resonance in the QR spectrum.

9. The apparatus of claim 8, further comprising determining a temperature of the search volume, wherein:

detecting the analyte within the search volume comprises comparing a frequency of the QR resonance to an expected frequency for the analyte at the temperature of the search volume.

10. The method of claim 8, further comprising determining a lineshape of the QR resonance, wherein:

detecting the analyte within the search volume comprises comparing the lineshape of the QR resonance to an expected lineshape for the analyte.

11. The method of claim 8, wherein the search volume is excited with an electromagnetic field power of less than 1 W.