[en] The probe consists of a radiation detector composed of a scintillation crystal and a photomultiplier, of a high voltage supply, an amplitude amplifier, two amplitude discriminators and a selection circuit, placed in a steel case. The parallel connection of the amplitude discriminators between the amplitude amplifier and the selection circuit is advantageous. Signal transmission is effected along a single lead. The probe is in fact a single-channel analyzer and allows measurement of gamma and X radiations in geology, dosimetry and industries. (M.D.)