USE OF GAMMA-GAMMA COINCIDENCE TECHNIQUE IN INVESTIGATING THE TRANSMITTED GAMMA- RAYS

A. Elawi, Mahmoud; Essa Hassan, Qutaiba

	USE OF GAMMA-GAMMA COINCIDENCE TECHNIQUE IN INVESTIGATING THE TRANSMITTED GAMMA- RAYS
Tikrit Journal of Pure Science
Article 1, Volume 18, Issue 2, 2013, Pages 221-230
Authors
Mahmoud A. Elawi; Qutaiba Essa Hassan
Abstract
Agamma-gamma fast-slow coincidence spectrometer is installed composed of two 3″ X 3″ NaI(TI) scintillation detectors and the related electronic units to investigate some effects that may occur for the photopeak after the -ray penetration from certain thicknesses of different materials and comparing this with the singles spectra and using the obtained spectrum in calculating some parameters of spectroscopic measurements like attenuation coefficient . A 22Na source is used in the measurements with a relatively low activity ( >0.1 µCi) . The time spectrum is measured without absorbing materials using the CFD to derive fast timing pulses with isolating slow rise time pulses to improve time resolution that was found to be about 7ns . Coincidence spectra are measured using 22Na located between the face-to-face detectors. The 0.511 MeV gate is selected for the detector that register spectra in air while the other detector registers the coincident spectrum with the former but after the gamma penetration through the absorber . Also the latter detector registers the singles spectrum of the penetrating gamma without using the whole coincidence spectrometer. Linear and mass attenuation coefficients measurements are carried out for lead and iron materials locally available with different thicknesses and square sheets (10X10cm) . The mass attenuation coefficient are measured from the coincidence spectra and found to be 0.1114 and 0.0686 cm2/g for Pb and Fe, respectively; while from the singles were spectra the coefficient found to be 0.14559 and 0.0976for Pb and Fe, respectively . These values are in good agreement with those published internationally (at 0.500 MeV) taking into consideration that the latter are measured for the three main interactions of ray . These results and spectra shapes show the possibility of using the coincidence spectrum is measuring more parameters than that are ordinary obtained from singles spectra. In addition to the reduction of background and Compton distribution from coincidence spectra which are clearly simplified .

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