Abstract: An analyzer for detecting explosives has at least one source and a plurality of gamma ray detectors. An article to be analyzed is moved adjacent the source and detectors and is subjected to neutrons which generate gamma rays in any nitrogen in the article. The gamma rays are detected and analyzed to determine the nitrogen concentration within the article. In order to achieve an area of uniform detection there are a plurality of detectors equidistant both from each source and from the article to be analyzed. In order to avoid a decrease in sensitivity away from the sources and detectors, there may be a second opposing array of sources and detectors on the opposite side of the articles. For greatest uniformity of detection, a source in one array opposes a detector in the other array and vice versa. Transmission of radiation from the analyzer is kept at safe levels by enclosing the analyzer within shielding which includes shield members extending from a trolley or other transport mechanisms.

Abstract: A method and an apparatus are provided for measuring the flow rate of a fluid in a duct, for example in an under-sea crude oil pipeline, in which samples of a radioactive tracer are injected, at intervals, into the duct and the passage of the samples of tracer detected by a scintillator. The tracer is generated by irradiating a large volume of a liquid obtained from the environment of the duct with a neutron source, so that the sample has been irradiated for a prolonged period prior to injection.

Abstract: A gold sorting plant in which the gold content of lumps of ore is measured by means of a neutron activation analytical technique. Separate lumps of gold ore are graded in two sizes which are presented to an irradiator such as to irradiate them uniformly. The energized lumps of ore are conveyed to an analyzer/sorter station where the intensity of .gamma.-rays having an energy of 297 KeV from each lump of ore is measured, and it is accepted or rejected for further processing. Various forms of irradiator and analyzer/sorter are described.

Abstract: An apparatus for ore sorting includes a neutron irradiator (12), and a detector assembly (14) for detecting gamma radiation emitted by irradiated lumps (21) of the ore. The irradiated lumps (21) after discharge from the irradiator (12), are divided into two channels (30) by at least one bifurcating device (28) held above a relatively high speed conveyor (26) transporting the lumps (21). Each channel (30) is subsequently divided into three streams (37, 38, 39) by diverting selected lumps (21) from the channel (30) as the lumps (21) are projected from the end of the high speed conveyor (26). The diverted lumps (21) in each stream (37, 38, 39) are allowed to fall on to a relatively low speed conveyor (50) which then presents the lumps (21) to the detector assembly (14).

Abstract: An irradiator for irradiating lumps of ore, to activate a selected substance in the ore by neutron activation, consists of a cylindrical chamber 10, a vibrated conical base 20 to control passage of the lumps through the chamber 10, and at least one coaxial annular neutron source 30 at one end of the chamber 10. The neutron source 30 is arranged so that all the lumps of ore are activated uniformly.