| 摘要 |
A Multiphoton Densitometer (MP-Densitometer) for remote density measurement uses special multiphoton sources with very low, licen se-exempt activity to measure the density of samples. For gas/oil/water mixture inside 3 inch steel pipes, the measurement precision, using a 2 microCi source, is substantially equivalent to that obtained by a prior-art gamma densitometer using a 30 milliCi source. Using a 1 microCi source the MP Densitometer measures the density, with uncertainty less than 1 %, of fluids inside pipes with a range of diameters up to 10 inches. The invention achieves very low background (orders of magnitude lower than for prior-art gamma densitometers) through selection of densitometer elements, geometry, electronics, and software. Reduction of system uncertainties, a temperature compensation scheme, active temperature regulation, real-time statistical analysis, and smoothing of the output signal allowed the elimination of temperature effects and pile-up artifacts. With a very low activity source, the MP-Densitometer has an accuracy in density measurements of 1 % for oil/water laminar flow. The uncertainty is 0.5 % for longer measurement tim es on the order of a few minutes.
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