DETECTION OF EXPLOSIVE AND NARCOTICS BY LOW POWER LARGE SAMPLE VOLUME NUCLEAR QUADRUPOLE RESONANCE (NQR)

摘要

The sensitive detection of explosives and narcotics by nuclear quadrupole resonance (NQR) is performed at low rf powerby assuring that the rf field strength is larger than the local magnetic field. Additionally, it has been recognized thatsignal-to-noise ratio of a signal induced by a specimen of fixed size decrease by only the square root of the coil size. Thus, rather thanscaling power linearly with coil size, as conventionally done to maintain the same rf field intensity, the power needs only beincreased by the square root of the increased coil size to assure maintenance of the same signal to noise ratio. This techniquepermits the use of larger coils than previously used. The invention is useful for both volume coils and surface coils.