Abstract: A method, system, and attachment for sorting articles, such as laundry or the like whereby each article includes as a part thereof a quantity of each of a number of different materials of the type which each produce secondary radiation at a characteristic energy level when x-ray, gamma or other radiation impinges thereon, the combination of materials forming a code uniquely identifing the article. Each article is passed through a pneumatic tube or on a conveyor line substantially one at a time past a source of radiation and a multi-channel energy level detector which produces an electrical output signal indicating the article, and also indicating when two or more combination codes are being simultaneously passed. The articles are then diverted in accordance with the electrical signal.