Patent ID: 7375525

Claim:
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 Δf NQR , and wherein f 1 and f 2 are the frequencies corresponding to the end points of the range of frequencies Δf 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 f 1 and f 2 , 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 f 1 and f 2 to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the sensor resonance frequencies between f 1 and f 2 ; c) detecting a nuclear quadrupole resonance signal, if any, using the sensors with resonance frequencies between f 1 and f 2 ; d) retuning the n sensors to p different resonance frequencies, at least two of which are between f 1 and f 2 , wherein at least two of the resonance frequencies between f 1 and f 2 are different from any of the previously tuned resonance frequencies between f 1 and f 2 , and where 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 f 1 and f 2 to excite any nuclear quadrupole resonance having a resonance frequency at one or more of the retuned frequencies between f 1 and f 2 ; f) detecting a nuclear quadrupole resonance signal to indicate the presence of quadrupole nuclei in the sample, if any, using the sensors with retuned resonance frequencies between f 1 and f 2 ; and g) repeating steps (d), (e) and (f) until the whole range of frequencies between f 1 and f 2 has been scanned, wherein p can have the same or different values each time step (d) is repeated.