Abstract: Apparatus for continuously determining the areal density along a length of a material includes a radioactive source and a scintillating receiver. In a first embodiment, the invention measures the thickness of a traveling web simultaneously at multiple points across its full width. The apparatus includes a radioactive source which extends across one side of the web. A detector array, on the opposite side of the web, detects the emission from the source through the web. The array includes scintillating fibers and multi- or single-anode photomultipliers which may be connected by a scintillating or non-scintillating fiber optic elements to the photomultiplier. In a second embodiment, the invention continuously detects the fill level of a plurality of containers as they are conveyed between the receiver and detector. A scintillating fiber receiver may have its fibers arranged either vertically or horizontally.

Abstract: Apparatus for continuously determining the basis weight of paper simultaneously at multiple points across the full width of a substrate. The apparatus includes a radioactive source which extends across one side of the web of paper. A detector array, on the opposite side of the substrate, detects the emission from the source. The array includes scintillating fibers and multi- or single-anode photomultipliers which may be connected by a scintillating or non-scintillating fiber optic elements to the photomultiplier.