Ge 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 measuring conditions resemble those adopted during calibration.Our ORTEC GEM70 P4-95 P type Ge γ-ray spectrometer was calibrated by measuring K
Ra
Th and U standards from Ionizing Radiation Division National Institute of Metrology.Different type samples were analyzed by both ICP-MASS and the Ge γ-ray spectrometer.The results show that 8 hours measured time are enough and the calibration is accurate.