USE OF MULTIPLE SENSORS IN A NUCLEAR QUADROPOLE RESONANCE DETECTION SYSTEM TO IMPROVE MEASUREMENT SPEED

• US 20080094061A1
• Filed: 12/15/2004
• Published: 04/24/2008
• Est. Priority Date: 12/15/2003
• Status: Active Grant

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Wilker, Charles, Laubacher, Daniel B., McCambridge, James D.
• Granted Patent: US 7,375,525 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01N 24/084 Detection of potentially hazardous samples, e.g. toxic samples, explosives, drugs, firearms, weapons
• CPC Class Codes: G01R 33/441 Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging

Abstract

The use of multiple sensors improves the measurement speed of a nuclear quadrupole resonance detection system when the nuclear quadrupole resonance frequency is known only within a range of frequencies.

Claims

1-16. -16. (canceled)

17. In a system for scanning a sample to detect nuclear quadrupole resonance, where the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample is known only within a range of frequencies Δ

f_NQR, and wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, a method for improving the measurement speed of the system, comprising;

a) providing n sensors to detect the nuclear quadrupole resonance signal,

wherein the n sensors are high temperature superconductor self-resonant planar coils used solely to detect the nuclear quadrupole resonance signal, and

wherein the n sensors are tuned to m different resonance frequencies, at least two of which are between f₁ and f₂, and

wherein n is greater than 1 and 2≦

m≦

n;

b) irradiating the sample with an RF signal that has frequencies corresponding to the sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the sensor resonance frequencies between f₁ and f₂;

c) detecting a nuclear quadrupole resonance signal, if any, using the sensors with resonance frequencies between f₁ and f₂;

d) retuning the n sensors to p different resonance frequencies, at least two of which are between f₁ and f₂, wherein at least two of the resonance frequencies between f₁ and f₂ are different from any of the previously tuned resonance frequencies between f₁ and f₂, and wherein 2≦

p≦

n,

wherein the resonance frequency of each of the n sensors is tuned and retuned using n circuits, one for each of the n sensors, wherein each circuit of the n circuits is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant sensor, a variable reactance in series with the single loop or coil, and means to connect the variable reactance to, and disconnect the variable reactance from, the single loop or coil;

e) irradiating the sample with an RF signal that has frequencies corresponding to the retuned sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the retuned frequencies between f₁ and f₂;

f) detecting a nuclear quadrupole resonance signal, if any, using the sensors with retuned resonance frequencies between f₁ and f₂; and

g) repeating steps (d), (e) and (f) until the whole range of frequencies between f₁ and f₂ has been scanned, wherein p can have the same or different values each time step (d) is repeated.

18. The method of claim 17, wherein the variable reactance is comprised of two or more capacitors in parallel, each of which capacitors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch.

19. The method of claim 17, wherein the variable reactance is comprised of two or more inductors in series, each of which inductors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch that can short-circuit the inductor and thereby essentially remove it from the circuit.

49. The nuclear quadrupole resonance detection system of claim 17, wherein the sample comprises explosives, drugs or other contraband.

20. In a system for scanning a sample to detect nuclear quadrupole resonance, where the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample is known only within a range of frequencies Δ

f_NQR, and wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, a method for improving the measurement speed of the system, comprising;

a) providing n sensors to detect the nuclear quadrupole resonance signal,

wherein the n sensors are high temperature superconductor self-resonant planar coils used solely to detect the nuclear quadrupole resonance signal, and

wherein the n sensors are tuned to m different resonance frequencies, at least two of which are between f₁ and f₂, and

wherein n is greater than 1 and 2≦

m≦

n;

b) irradiating the sample with an RF signal that has frequencies corresponding to the sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the sensor resonance frequencies between f₁ and f₂;

c) detecting a nuclear quadrupole resonance signal, if any, using the sensors with resonance frequencies between f₁ and f₂;

d) retuning the n sensors to p different resonance frequencies, at least two of which are between f₁ and f₂, wherein at least two of the resonance frequencies between f₁ and f₂ are different from any of the previously tuned resonance frequencies between f₁ and f₂, and wherein 2≦

p≦

n,

wherein the resonance frequency of each of the n sensors is tuned and retuned using one or more circuits, wherein each the circuits is comprised of a variable reactance;

e) irradiating the sample with an RF signal that-has frequencies corresponding to the retuned sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the retuned frequencies between f₁ and f₂;

f) detecting a nuclear quadrupole resonance signal, if any, using the sensors with retuned resonance frequencies between f₁ and f₂; and

g) repeating steps (d), (e) and (f) until the whole range of frequencies between f₁ and f₂ has been scanned, wherein p can have the same or different values each time step (d) is repeated.

50. The nuclear quadrupole resonance detection system of claim 20, wherein the sample comprises explosives, drugs or other contraband.

21. In a system for scanning a sample to detect nuclear quadrupole resonance, where the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample is known only within a range of frequencies Δ

f_NQR, and wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, a method for improving the measurement speed of the system, comprising;

a) providing n sensors to detect the nuclear quadrupole resonance signal,

wherein the n sensors are each comprised of two coupled high temperature superconductor self-resonant planar coils used solely to detect the nuclear quadrupole resonance signal, and

wherein the n sensors are tuned to m different resonance frequencies, at least two of which are between f₁ and f₂, and

wherein n is greater than 1 and 2≦

m≦

n;

b) irradiating the sample with an RF signal that has frequencies corresponding to the sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the sensor resonance frequencies between f₁ and f₂;

c) detecting a nuclear quadrupole resonance signal, if any, using the sensors with resonance frequencies between f₁ and f₂;

d) retuning the n sensors to p different resonance frequencies, at least two of which are between f₁ and f₂, wherein at least two of the resonance frequencies between f₁ and f₂ are different from any of the previously tuned resonance frequencies between, f₁ and f₂, and wherein 2≦

p≦

n,

wherein the resonance frequency of each of the n sensors is tuned and retuned using n circuits, one for each of the n sensors, wherein each circuit of the n circuits is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant sensor, a variable reactance in series with the single loop or coil, and means to enable the variable reactance to be connected to and disconnected from the single loop or coil;

e) irradiating the sample with an RF signal that has frequencies corresponding to the retuned sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the retuned frequencies between f₁ and f₂;

f) detecting a nuclear quadrupole resonance signal, if any, using the sensors with retuned resonance frequencies between f₁ and f₂; and

g) repeating steps (d), (e) and (f) until the whole range of frequencies between f₁ and f₂ has been scanned, wherein p can have the same or different values each time step (d) is repeated.

22. The method of claim 21, wherein the variable reactance is comprised of two or more capacitors in parallel, each of which capacitors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch.

23. The method of claim 21, wherein the variable reactance is comprised of two or more inductors in series, each of which inductors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch that can short-circuit the inductor and thereby essentially remove it from the circuit.

51. The nuclear quadrupole resonance detection system of claim 21, wherein the sample comprises explosives, drugs or other contraband.

24. In a system for scanning a sample to detect nuclear quadrupole resonance, where the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample is known only within a range of frequencies Δ

f_NQR, and wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, a method for improving the measurement speed of the system, comprising;

a) providing n sensors to detect the nuclear quadrupole resonance signal,

wherein the n sensors are each comprised of two coupled high temperature superconductor self-resonant planar coils used solely to detect the nuclear quadrupole resonance signal, and

wherein the n sensors are tuned to m different resonance frequencies, at least two of which are between f₁ and f₂, and

wherein n is greater than 1 and 2≦

m≦

n;

b) irradiating the sample with an RF signal that has frequencies corresponding to the sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the sensor resonance frequencies between f₁ and f₂;

c) detecting a nuclear quadrupole resonance signal, if any, using the sensors with resonance frequencies between f₁ and f₂;

d) retuning the n sensors to p different resonance frequencies, at least two of which are between f₁ and f₂, wherein at least two of the resonance frequencies between f₁ and f₂ are different from any of the previously tuned resonance frequencies between f₁ and f₂, and wherein 2≦

p≦

n,

wherein the resonance frequency of each of the n sensors is tuned and retuned using one or more circuits, wherein each of the circuits is comprised of a variable reactance;

e) irradiating the sample with an RF signal that has frequencies corresponding to the retuned sensor resonance frequencies between f₁ and f₂ to excite any nuclear quadrupole resonance having a resonance-frequency at one or more of the retuned frequencies between f₁ and f₂;

f) detecting a nuclear quadrupole resonance signal, it any, using the sensors with retuned resonance frequencies between f₁ and f₂; and

g) repeating steps (d), (e) and (f) until the whole range of frequencies between f₁ and f₂ has been scanned, wherein p can have the same or different values each time step (d) is repeated.

52. The nuclear quadrupole resonance detection system of claim 24, wherein the sample the sample comprises explosives, drugs or other contraband.

25-40. -40. (canceled)

41. A nuclear quadrupole resonance detection system for scanning a sample in which the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample lie within a range of frequencies Δ

f_NQR, wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, comprising;

a) n sensors to detect the nuclear quadrupole resonance signal, wherein n is greater than 1, wherein the n sensors are high temperature superconductor self-resonant planar coils which solely detect the nuclear quadrupole resonance signal;

b) means for

(i) tuning the n sensors to m different resonance frequencies at least two of which are between f₁ and f₂, wherein 2≦

m≦

n,

(ii) retuning the n sensors to p different resonance frequencies at least two of which are between f₁ and f₂, wherein at least two of the retuned resonance frequencies between f₁ and f₂ are different from any of the previously tuned or retuned resonance frequencies between f₁ and f₂, wherein 2≦

p≦

n, and wherein p has the same or different values each time the n sensors are retuned, and

(iii) repeatedly retuning the n sensors to p different resonance frequencies until the whole range of frequencies between f₁ and f₂ has been scanned,

wherein the means to tune and retune the resonance frequency of each of the n sensors comprises n circuits, one for each of the n sensors, wherein each of the n circuits is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant sensor, a variable reactance in series with the single loop or coil, and means to connect the variable reactance to, and disconnect the variable reactance from, the single loop or coil; and

c) means for irradiating the sample with an RF signal that has

(i) frequencies corresponding to the originally tuned resonance frequencies between f₁ and f₂, or

(ii) frequencies corresponding to any retuned resonance frequencies between f₁ and f₂,

thereby to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the resonance frequencies between f₁ and f₂.

42. The nuclear quadrupole resonance detection system of claim 41, wherein the variable reactance is comprised of two or more capacitors in parallel, each of which capacitors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch.

43. The nuclear quadrupole resonance detection system of claim 41, wherein the variable reactance is comprised of two or more inductors in series, each of which inductors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch to short-circuit the inductor and essentially remove it from the circuit.

53. The nuclear quadrupole resonance detection system of claim 41, wherein the sample the sample comprises explosives, drugs or other contraband.

44. A nuclear quadrupole resonance detection system for scanning a sample in which the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample lie within a range of frequencies Δ

f_NQR, wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies ≢

f_NQR, comprising;

a) n sensors to detect the nuclear quadrupole resonance signal, wherein n is greater than 1, wherein the n sensors are high temperature superconductor self-resonant planar coils which solely detect the nuclear quadrupole resonance signal;

b) means for

(i) tuning the n sensors to m different resonance frequencies at least two of which are between f₁ and f₂, wherein 2≦

m≦

n,

(ii) retuning the n sensors to p different resonance frequencies at least two of which are between f₁ and f₂, wherein at least two of the retuned resonance frequencies between f₁ and f₂ are different from any of the previously tuned or retuned resonance frequencies between f₁ and f₂, wherein 2≦

p≦

n, and wherein p has the same or different values each time the n sensors are retuned, and

(iii) repeatedly retuning the n sensors to p different resonance frequencies until the whole range of frequencies between f₁ and f₂ has been scanned,

wherein the means to tune and retune the resonance frequency of each of the n sensors comprises one or more circuits, each of which circuits is comprised of a variable reactance; and

c) means for irradiating the sample with an RF signal that has

(i) frequencies corresponding to the originally tuned resonance frequencies between f₁ and f₂, or

(ii) frequencies corresponding to any retuned resonance frequencies between f₁ and f₂,

thereby to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the resonance frequencies between f₁ and f₂.

54. The nuclear quadrupole resonance detection system of claim 44, wherein the sample the sample comprises explosives, drugs or other contraband.

45. A nuclear quadrupole resonance detection system for scanning a sample in which the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample lie within a range of frequencies Δ

f_NQR, wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, comprising

a) n sensors to detect the nuclear quadrupole resonance signal, wherein n is greater than 1, wherein the n sensors are each comprised of two coupled high temperature superconductor self-resonant planar coils which solely detect the nuclear quadrupole resonance signal;

b) means for

(i) tuning the n sensors to m different resonance frequencies at least two of which are between f₁ and f₂, wherein 2≦

m≦

n,

(ii) retuning the n sensors to p different resonance frequencies at least two of which are between f₁ and f₂, wherein at least two of the retuned resonance frequencies between f₁ and f₂ are different from any of the previously tuned or retuned resonance frequencies between f₁ and f₂, wherein 2≦

p≦

n, and wherein p has the same or different values each time the n sensors are retuned, and

(iii) repeatedly retuning the n sensors to p different resonance frequencies until the whole range of frequencies between f₁ and f₂ has been scanned,

wherein the means to tune and retune the resonance frequency of each of the n sensors comprises n circuits, one for each of the n sensors, wherein each of the n circuits is comprised of a single loop or coil to inductively couple the circuit to the high temperature superconductor self-resonant sensor, a variable reactance in series with the single loop or coil, and means to connect the variable reactance to, and disconnect the variable reactance from, the single loop or coil; and

c) means for irradiating the sample with an RF signal that has

(i) frequencies corresponding to the originally tuned resonance frequencies between f₁ and f₂, or

(ii) frequencies corresponding to any retuned resonance frequencies between f₁ and f₂,

thereby to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the resonance frequencies between f₁ and f₂.

46. The nuclear quadrupole resonance detection system of claim 45, wherein the variable reactance is comprised of two or more capacitors in parallel, each of which capacitors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch.

47. The nuclear quadrupole resonance detection system of claim 45, wherein the variable reactance is comprised of two or more inductors in series, each of which inductors can be individually connected to or disconnected from the single loop or coil by a mechanical or electrical switch to short-circuit the inductor and essentially remove it from the circuit.

55. The nuclear quadrupole resonance detection system of claim 45, wherein the sample the sample comprises explosives, drugs or other contraband.

48. A nuclear quadrupole resonance detection system for scanning a sample in which the frequency of the nuclear quadrupole resonance of any quadrupole nuclei in the sample lie within a range of frequencies Δ

f_NQR, wherein f₁ and f₂ are the frequencies corresponding to the end points of the range of frequencies Δ

f_NQR, comprising;

a) n sensors to detect the nuclear quadrupole resonance signal, wherein n is greater than 1, wherein the n sensors are each comprised of two coupled high temperature superconductor self-resonant planar coils which solely detect the nuclear quadrupole resonance signals

b) means for

(i) tuning the n sensors to m different resonance-frequencies at least two of which are between f₁ and f₂, wherein 2≦

m≦

n,

(ii) retuning the n sensors to p different resonance frequencies at least two of which are between f₁ and f₂, wherein at least two of the retuned resonance frequencies between f₁ and f₂ are different from any of the previously tuned or retuned resonance frequencies between f₁ and f₂, wherein 2≦

p≦

n, and wherein p has the same or different values each time the n sensors are retuned, and

(iii) repeatedly retuning the n sensors to p different resonance frequencies until the whole range of frequencies between f₁ and f₂ has been scanned,

wherein the means to tune and retune the resonance frequency of each of the n sensors comprises one or more circuits, each of which circuits is comprised of a variable reactance; and

c) means for irradiating the sample with an RF signal that has

(i) frequencies corresponding to the originally tuned resonance frequencies between f₁ and f₂, or

(ii) frequencies corresponding to any retuned resonance frequencies between f₁ and f₂,

thereby to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the resonance frequencies between f₁ and f₂.

56. The nuclear quadrupole resonance detection system of claim 48, wherein the sample the sample comprises explosives, drugs or other contraband.