Abstract
A new and accurate method to determine the mass attenuation coefficient, μm, for low photon energy employing NaI(Tl) X-ray detector and radioactive source is described. Effect of size of collimator and the selection of width of photopeak for integration on the contribution from scattered photons to the transmitted intensity is studied systematically and optimum size of collimator and photopeak limits for integration are established. With a 6 mm diameter collimator and FWHM for photopeak limits it was found that Beer-Lambert's law was rigorously valid over transmission range of 50–2%. Using this method μm was determined for six elements that covered a wide atomic number range (12 < Z < 73) and two biological equivalent materials. The values so obtained agreed with theoretical values within 1% establishing the validity and accuracy of the present method which uses inexpensive moderate resolution detector. As the method permits higher transmission range better counting statistics is an added advantage.
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