| 摘要 |
Radiation scatter apparatus for measuring the thickness of a thin overlay and the density of overlay (T) and substrate (B) compises a source (20) emitting gamma radiation into overlay and substrate, and at least three scattered radiation detectors (22, 24, 26) each with filter to measure radiation different to that measured by the others. A recorder separately records data from each detector. The data is pref. recorded as count rates and there is a strorage holding at least three equations relating recorded data to densities and thickness, with a computer to solve the equations and display the results. The method is partic. for testing an overlay applied in a pavement maintenance or resurfacing operation, with the detectors in a nuclear gauge placed over the overlay.
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