Determination of 90Sr by measuring 90Y Cerenkov Counting

To determine 90 Sr activity in environmental samples advanced cerenkov counting using liquid scintillation counter has been widely investigated. Separated 90 Y in equilibrium with 90 Sr in a solution can be counted using a Cerenkov measurement without scintillation. In addition an equilibrium 90 Sr/ 90 Y in a solution can be directly measured using 90Y Cerenkov counting. The 90 Sr Cerenkov counting is considered negligible due to its very low counting efficiency. In this work the Cerenkov technique to measure 90Y counting from a series of 90 Sr/ 90 Y solution was studied in the two matrices, 16 mL of 1 M HNO 3 and 0.1 M HCl. A suitable counting window was found to be in the range of 0–50 keV. Cerenkov counting in the HNO 3 solution obtained a lower background count rate (2.2 CPM) than those of the HCl solution (3.32 CPM). 90 Y counting efficiencies of the HNO3 solution (between 56.73 and 64.61%) were slightly lower than those of HCl solution (between 45.19 and 66.34%). However, FOMs of the HNO 3 (between 1418 and 1839) were much higher than those of HCl (between 615 and 1326). In this case the HNO 3 solution is a better matrix for the Cerenkov counting of 90 Y.