Portable field NaI(Tl) γ-ray spectrometer is an important tool for determining potassium

uranium and thorium contents in sediments. The results depend on accuracy of the calibration and the extent to which the measur- ing conditions resemble those adopted during calibration. e.g. geometry

background radiation

components and den- sities of materials

etc. Calibration of a field ORTEC MicroNomad NaI(Tl) γ-ray spectrometer

in auger hole geome- try was done using the Oxford calibration blocks with known contents of radioisotopes of K

U and Th. A granite block similar to Heidelberg’s calibration block was set up at SKLED. It can be used as a calibration block to check the γ-ray spectrometer. Contents of K

U and Th of the granite block were analyzed using different methods.