Energy resolution and detection efficiency were compared between two sizes of cerium bromide (CeBr 3 ) scintillators, three sizes of lanthanum bromide (LaBr 3 :Ce) scintillators, three sizes of sodium iodide (NaI:Tl) scintillators, and a lanthanum chloride (LaCl 3 :Ce) scintillator. Comparisons are made of key parameters such as energy resolution, detection efficiency, linearity, and self-activity of CeBr 3 , LaBr 3 :Ce, LaCl 3 :Ce, and NaI:Tl scintillator detectors. The scintillator detectors are tested by comparing the peak separation and identification in the energy range up to 3.0 MeV using 133 Ba, 152 Eu, and naturally occurring radioactive materials [1]. The study has shown that CeBr 3 scintillator detectors provided by Saint-Gobain offer better resolution than NaI:Tl scintillator detectors. CeBr3 detectors could resolve some closely spaced peaks from 133 Ba and 152 Eu, which NaI:Tl could not. LaBr 3 :Ce has slightly better resolution, and a slightly higher efficiency than CeBr 3 . In this work, "self-activity" of each of these four detector types was measured by operating the detectors themselves. A comparison of the intrinsic activity for all of the detectors in this study is demonstrated. For CeBr 3 , the self-activity present may be reduced, or even eliminated in the future, through improved processes for growing the material. It will be discussed if, and under what conditions, CeBr 3 may be better than LaBr 3 :Ce and LaCl 3 :Ce for detection of certain special nuclear material γ-rays [2]. An overall advantage of CeBr 3 detectors over lanthanum halide and NaI:Tl detectors will be discussed.