Appearance of Chance Coincidence in Attenuation Measurements Carried out by using Coincidence Technique

The appearance of chance coincidence in attenuation measurements using technique is investigated. A two 3"*3" NaI(Tl) detector spectrometer with 0.5 μ Ci Na-22 source were used. Two different materials forms, namely mixed metallic powders and Fe-sheets are ratio counts to total real coincidences annihilation peak had ranged between (0.007-0.013) (0.011-0.036) for the thicknesses mentioned respectively. linear coefficients due at 1274keV 0.1 0.38 cm-1 assuring proportionality energy. When treated as being "lost" from added again latter, no change observed coefficient that calculated before taking accidental into consideration.