| 摘要 |
An analyser for detecting explosives has at least one source (10) and a plurality of gamma ray detectors (15). An article (18) to be analysed is moved adjacent the source (10) and detectors (15) and is subjected to neutrons which generate gamma rays in any nitrogen in the article (18). The gamma rays are detected and analysed to determine the nitrogen concentration within the article (18). In order to achieve an area of uniform detection there are a plurality of detectors (15) equidistant both from each source (10) and from the article (18) to be analysed. In order to avoid a decrease insensitivity away from the sources (10) and detectors (15), there may be a second opposing array of sources (10) and detectors (15) on the opposite side of the articles (18). For greatest uniformity of detection, a source (10) in one array opposes a detector (15) in the other array and vice versa. Transmission of radiation from the, analyser is kept at safe levels by enclosing the analyser within shielding (37) which includes shield members (43) extending from a trolley (40) or other transport means. |
