METHOD TO DETECT TRI-BAND NUCLEAR QUADRUPOLE RESONANCE Russian patent published in 2013 - IPC G01N24/08 

FIELD: power engineering.

SUBSTANCE: sample is exposed to radiation at the frequency υ_ by the first radio frequency pulse, by the second radio frequency pulse at the frequency υ₊, pulses are applied at frequencies of appropriate NQR transitions, the signal is recorded at the third frequency of NQR υ₊. At the same time all coils of the sensor are mutually orthogonal, besides, a multi-pulse sequence is applied, which consists of composite pulses, where each pulse is a combination of three pulses - the first pulse is applied at the frequency υ_, the second pulse is applied at the frequency υ₀, then the third pulse is applied at the frequency υ_. The first N cycles of the multi-pulse sequence contain a composite pulse, in which the second pulse has a phase 0°, the second N cycles of the multi-pulse sequence contain a composite pulse, in which the second pulse has the phase 180°, the signal is recorded at the frequency υ₊, then coherent accumulation of received signals takes place in each sequence, and by subsequent subtraction from signals accumulated after the first N pulses, signals accumulated after the second N pulses.

EFFECT: increased signal-noise ratio.

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