عنوان مقاله [English]
نویسنده [English]چکیده [English]
In this investigation, it is tried to measure the spectrum of emitted gamma from 22Na source with energy of 511 that is created by annihilation of electron and positron in different angle by two NaI detectors with resolving time 4 . This measurement is done in states with using lead shielding and without using of them for detectors. Procedure of experiment is follow as: the two detectors are placed vertically on side of the positron source without using of lead shielding. Spectrum of the entrane gamma to detectors were recorded in the coincidence state. Then detectors was designed to laed shielding. Two detectors were placed in front of the source and again Spectrum of the entrane gamma to detectors were recorded in the coincidence state. The measured area below of 511 gamma peak in gamma spectrum for different angles shows more narrow width for the case that lead shielding used than the case that lead shielding did not used and this is because of reducing campton effect by using lead shielding.