Absolute activity measurement of short lived and low level sources

The aim of this project is to measure the absolute activity of short lived isotopes that decay by positive beta particle (¿+). Therefore, the activity of short lived isotope 18F has been measured by three methods. Firstly, it was measured by 4¿ ionization chamber. Secondly, it was measured by detector efficiency method. In this method three NaI (TI) scintillation detectors with different volumes and geometry have been characterized in term of energy response, resolution, efficiency and linearity using calibration sources. Thirdly, it was measured by gamma-gamma coincidence. The experiment designed, constructed and tested a suitable system for measuring low activity samples and 18F preparation was done in the Positron Imaging Centre at Birmingham University.