Determination of Resolution and Detection Efficiency of NaI (Tl) Scintillation Gamma-Ray Spectrometer

NaI (Tl) scintillation detector is the most commonly used scintillator in experimental physics for the measurement of the gamma-ray activity of various samples. This detector is used in the measurement of nuclear reaction cross-section induced by neutrons and protons in the activation technique. In addition, the scintillation detector has a lot of applications in the elemental analysis of various and compounds, alloys using activation analysis. In each application, the precise values of detection efficiency for different gamma energies and knowledge of detector resolution for different gamma energies are necessary. The detection efficiency and resolution depend on the detector size and different detector parameters. Therefore it is essential to know these parameters for NaI detector before applying of detector for the quantitative analysis purpose. With this intention, in the present work, detection efficiency and resolution of NaI (Tl) scintillation detector are measured and optimized for following gamma-ray energies: 121.78 keV, 244.69 keV, 344.28 keV, 662 keV, 778.9 keV, 1173.81 keV, and 1332.91 keV. Values of detection efficiencies for these gamma energies are found to be respectively 11.28 %, 20.68 %, 3.35 %, 2.37 %, and 2.17 %. The values of percent resolution for above different gamma-ray energies are found to be 11.12 %, 10.93 %, 10.45 %, 8.36%, 6.93 % , 6.19 % , and 5.81 % respectively. The standard gamma sources provided by the IAEA (International Atomic Energy Agency) are used in the present work. The result shows that the efficiency and resolution of NaI (Tl) detector decrease with increasing energy