A single-crystal scintillator material can include at least 50 wt % of rare-earth halide and comprising a polished first face. This material is integrated into an ionizing-radiation detector comprising a photoreceiver, the photoreceiver being optically coupled to the material via a face other than the polished first face. The material provides a good energy resolution and a high light intensity. The polishing may be carried out whatever the crystal orientation of the crystal. Loss of material due to this orientation is therefore prevented.