| 摘要 |
In the new and improved radiation apparatus disclosed herein for inspecting tubular goods, a radiation detector is coaxially positioned within a tubular member being axially translated along a selected inspection axis for receiving radiation from a uniquely-arranged radiation emitter facing the detector and rotating around the exterior of the tubular member. In the preferred embodiment disclosed herein, this unique radiation emitter includes an array of side-by-side radioactive sources of selected strengths respectively directed inwardly through laterally-spaced, generally-parallel focussing passages for producing individual sharply-defined radiation beams respectively having a transverse width substantially smaller than that of the active portion of the detector. The outer or flanking sources of the array are arranged in relation to the intermediate source so that the radiation beams of the two outer sources will be directed on opposite sides of the inspection axis and the radiation beam of the intermediate source will intersect the inspection axis. In this manner, lateral movements of the detector to one side or the other of the inspection axis will progressively bring the active portion of the detector into the radiation pattern produced by one of the flanking sources as the detector moves out of the radiation pattern of the intermediate source. Accordingly, by cooperatively selecting and positioning the sources in operative relation to one another and to the detector, a substantially constant radiation intensity will contact the detector when it is at any position within a selected boundary around the inspection axis so that random or erratic shifts of the detector within the moving tubular member will not affect the accuracy of the measurements being obtained.
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