M.Sc. Tezi Görüntüleme

      In this study, effects of collimator on mass attenuation coefficients was determined. In experiments, three different absorbers having low, middle and high atomic number were used. Measurements were conducted using the two different methods. Firstly, the collimator positioned between detector and absorber, was hold steady in 4 mm diameter and the collimator positioned between source and absorber was changed as 2 mm, 4 mm, 6 mm, 10 mm. Secondly, the collimator positioned between source and absorber was hold steady in 4 mm diameter and the collimator positioned between detector and absorber was changed as 2 mm, 4 mm, 6 mm, 10 mm. The attenuation coefficients were measured at four different energies from 6,93 to 59,54 keV using secondary excitation method. These energies were obtained using secondary targets such as Co, Cd, Sm and Am radioactive source. 59,54 keV gamma rays emitted from an annular radioactive source were counted by a Ultra LEGe detector with a resolution of 0.16 keV at 5.9 keV. Obtained values were compared with theoretical values.