Preparation of Indigenous Radioactive Air Filter Standard for Gamma Spectrometry

Gamma spectrometry technique is regularly used for the quantification of different gamma-emitting radionuclides in environmental matrices and other synthetic samples. This is a non-destructive comparative technique which requires the usage of Certified Reference materials from International agencies like IAEA, NIST, etc. Limited availability and high cost of these Certified Reference materials pose a major hindrance in their acquisition by radiometric laboratories, motivating their indigenous preparation. A total of five sets of two types of filter papers and one blank were prepared by spiking with variable activity of 226 Ra by gravimetric and volumetric measurements in a standard geometry. Efficiency of both filter paper standards together, varied from 19.7 to 20.3% in the selected geometry on HPGe-based high-resolution gamma spectrometry system. MDA values were also observed to be suitable for environmental air particulate measurements. The values of efficiencies and MDA obtained indicate that these air filter standards can qualify as candidate reference standards for regular gamma spectrometric counting of air particulates on filter paper media.