Explosive detection method and apparatus using selective gamma ray resonance absorption

摘要

An apparatus and method for determining the presence of certain elements or compounds within an object, wherein the object under examination contains both nuclei of a first type which exhibit nuclear magnetic resonance and nuclei of a second type which exhibit nuclear quadrupolar resonance. The apparatus and method involve subjecting the object to a magnetic field and to a radiation beam whose characteristics in the presence of a magnetic field and in the absence of a magnetic field can be measured. The radiation transmission and/or absorption "fingerprint" of a particular substance is experimentally determined and recorded in the presence of a magnetic field calculated to optimize a cross coupling between nuclei of the first (NMR) type and nuclei of the second (NQR) type. This reference is then utilized later as a basis on which to identify an unknown compound exhibiting the same radiation absorption and/or transmission characteristics in response to the same or similar magnetic field intensity. Specific types of radiation and specific magnetic field intensities are pre-selected as optimizing the detectability of specific NMR/NQR element pairs.