To better understand the energy resolution of the studied crystals in γ-ray spectrometry, the
contribution of various components to the overall energy resolution were analyzed for 662 keV
photopeak, and the results are presented in Table 2. The second column gives N, the number of
photoelectrons produced in the PMT. The third column gives ΔE/E, the overall energy resolution at 662
keV photopeak. The PMT contribution (δst) was calculated using Eq.2. From the values of ΔE/E and δst ,
the intrinsic resolution (δsc) was calculated using Eq.3.