3. Results
3.1. Energy spectra and light yield
Fig. 1 presents the comparison of the energy spectra of 662 keV γ-rays from a 137Cs source, as measured with LaCl3:Ce and NaI(Tl) crystals at a 3 µs shaping time constant. Note a very good energy resolution of LaCl3:Ce of 4.2% in comparison to the 6.5% observed with NaI(Tl). Poorer energy resolution than
that reported in [1-3] could be associated with the larger size of the tested sample, lower quality and its lower light output, see below. The same energy resolution was reported in [4] for the ∅16×19 mm crystal delivered by Saint Gobain. Photofractions in both the spectra correspond to 17.9 % and 21.4% respectively, reflecting the larger volume of the NaI(Tl) crystal.