[en] Within a supporting device in the shape of a container there is placed a filter mat from paper, glass fiber, or gel with individual surfaces covered with β-labelled cell cultures (e.g. for investigating the inclusion of radioactive thymidine in DNA) or a tape, on which material with different radioactive content is put by means of chromatography or electrophoresis. The container itself may consist of a glass or plastic scintillator and/or contain a scintillator in liquid, solid, or gel state. The scintillations are detected by one or several photodetectors arranged above or below the container. With the aid of a rack-and-pinion drive either the supporting device or the detector appliance may be moved along the x and y coordinates. (HP)