The Effect of Collimator Diameters on Buildup Factor by using Gamma – Gamma Coincidence System

Abstract

In this work buildup factor of aluminum and copper samples was studied for different thickness using a  gamma _  gamma coincidence technique and by use two collimator 10 and 7 mm, buildup factor  was calculated for thickness ranged between ( 0 - 9.6 ) cm of aluminum and ( 0 - 4.0 ) cm of copper  using  Na - 22  source with activity of   ( 1 micro Curie ) with single energy ( 0.511 MeV ) and by using ( 3 "× 3" ) sodium iodide detector  NaI (TI). The results showed that buildup factor was more accuracy when we used small diameter because this will decrease the scattering ray which make our calculations more acute for buildup factor which is very important in shielding process for gamma ray.

Keywords: Buildup factor, Gamma ray, Shield, Coincidence.