CALIBRATION OF A DUAL GAMMA-RAY SCANNER.

Cesium-137 (Cs) and Americium-241 (Am) are the most commonly used radio-isotopes in dual gamma-ray scanners to measure the density and moisture content of porous media. When these radioactive sources are placed in line with a single detector the more energetic source, Cs, affects the count rates of the weaker source, Am. The analysis of experimental data requires the removal of the Cs effects from the Am readings. The dual gamma-ray scanner used in the present study also has Am and Cs isotopes. Corrections on the Am readings are required in the analysis of the data obtained with this scanner as well. However, the method presented by Goit cannot be used because the construction of the scanner does not allow either of the sources to be removed from the radiation beam. A direct method which is called the 'Total Peak Area' (TPA) has been employed in this work to develop a calibration curve.