An automatic sample changer is described which permits direct comparison of the relative activation of samples simultaneously irradiated in a reactor without the need for decay time corrections of the measured results. The turntable of the sample charger may be loaded with 2 to a maximum of 90 γ-active solid samples for single and coincidence measurements. Special care was taken to achieve accurate positioning of the samples in the measuring position. The mechanical drive of the sample changer is pneumatic and the electronic control acts upon electropneumatic valves. It is possible to operate the sample changer for any number of samples within the set limits without changing the control electronics. The data are read out as a group of n numbers by a printer and/or tape punching device. The first two numbers represent the address of the data, and the following n-2 numbers the result of the measurement.