The experimental arrangement of the Compton scattering technique is shown in Fig. 1. The source system was mounted on a composite of adjustable stands. This setup can move in the transverse direction for proper beam alignment. The 137 Cs radio-active source of 15 mCi (555 MBq) strength was obtained from the Office of Atom for Peace (OAP), Thailand. The aluminium rod was used as the scattering rod. The Compton scatteredγ-rays were measured on a rotatable scintillator detector in the scattering