Calibration of Cylindrical NaI(Tl) Detector Using Different Perpendicular Radioactive Cylindrical Sources

Environmental samples containing some contaminated samples of a wide variety of characteristics are routinely analyzed using gamma-ray detectors. In this work the full energy peak efficiency of NaI(Tl) scintillation detectors 2"x2" and 3"x3" inches have been calculated experimentally by using perpendicular radioactive cylindrical sources and theoretically by applying an analytical efficiency transfer expression. This expression was based on including the ratio of the sourceto- detector effective solid angle. Measurements were made using the perpendicular cylindrical vials filled with 152Eu solution. The Calibration process covers a wide energy range starting from 121 up to 1408 keV. In addition, the self-attenuation factor was estimated by using the linear attenuation factor of the assayed source material and the geometrical configuration of the assay set-up at low source-detector distance. A remarkable agreement between measured and calculated efficiency values was observed.