A luminescent material can include a rare earth halide having a chemical formula of RE(1-A-B-C)HTADETBSETCXz, wherein RE is a rare earth element, HT is an element or an interstitial site that provides a hole trap, DET is a dopant that provides a relatively deep electron trap, SET is a dopant that provides a relatively shallow electron trap, X is one or more halides, each of A, B, and C has a value greater at least 0.00001 and at most 0.09, and Z has a value in a range of 2 to 4. In an embodiment, a ratio of B:C is selected so that luminescent material has good linearity performance. In another embodiment, the ratio of B:C can be in a range of 10:1 to 100:1.