A moldable and curing reflector material for an X-ray detector is disclosed. It includes a detector material which converts X-rays into light and is divided into a plurality of segments separated by the reflector material. The reflector material includes a polymer matrix which contains a first optically reflecting material and also a finely distributed gas and/or a second optically reflecting material, which is different than the first optically reflecting material. An X-ray detector is further disclosed, which contains a material of this type, along with a process for producing a material of this type and a process for producing an X-ray detector.