Abstract: A cesium iodide based scintillation material is obtained exhibiting a low afterglow and high radiation hardness; its preparation method is developed, too.The cesium iodide based scintillation material doped by thallium iodide contains an additional admixture of compound having the general formulaMe.sub.x (CO.sub.3).sub.y,where Me is a cationic admixture,1.ltoreq.X.ltoreq.2,1.ltoreq.Y.ltoreq.5,This material has in its absorption spectrum a stretching vibration band of CO.sub.3.sup.2- -ion about 7 .mu.m and a bending vibration band about 11.4 .mu.m, the absorption coefficient of the latter being from 1.4.multidot.10.sup.-3 to 2.multidot.10.sup.-2 cm.sup.-1.Preparation method of this scintillation material comprises the raw material cesium iodide melting, adding of the activating thallium iodide dope, introduction of cesium carbonate (3.multidot.10.sup.-4 to 5.multidot.10.sup.-3 % by mass) and a sodium salt (3.multidot.10.sup.-4 to 7.5.multidot.10.sup.