YSO, LSO, GSO and LGSO. A study of energy resolution and nonproportionality.

We have studied the nonproportionality and intrinsic energy resolution of c erium doped YSO, GSO, LSO and LGSO crystals. While LSO and YSO have similar light output, GSO acid LGSO have ca. 70% and 20% lower light output than L SO, respectively. YSO, a compound containing fairly light elements, was exp ected to have proportional light output vs. energy, like YAP:Ce. Surprising ly it has almost the same nonproportional as LSO and GSO. The nonproportion ality of YSO is followed by large values of intrinsic energy resolution. Th e comparison of the nonproportionality of YSO - LSO and YAP - LuAP pairs in dicates that high proportionality is connected with the structure of the cr ystal and not with the presence of light elements. To our knowledge, this i s the first study of nonproportionality and intrinsic resolution for LGSO.