Patent Number: 
Section: claims

1. An apparatus for detecting and locating a radioactive source emitting gamma rays, comprising: gamma-ray sensor;  a plurality of measuring means capable of receiving a light signal emitted by the sensor;  analyzing means for comparing signals output by the measuring means in order to determine a direction in which the source is offset with respect to a detection axis;  means for defining a central axis of the apparatus; and  means for imparting a movement to the apparatus in response to movement instructions as long as the analyzing means indicate that the central axis of the apparatus is not in correspondence with the source. 2. The apparatus as claimed in  claim 1 , characterized in that the means for sensing the gamma rays consist of a collimator and a scintillating crystal capable of emitting a light signal under the effect of a gamma ray. claim 1 3. The apparatus as claimed in  claim 2 , characterized in that the collimator has a central area comprising a plurality of mutually parallel channels which are perpendicular to the surface of said collimator. claim 2 4. The apparatus as claimed in  claim 3 , characterized in that the central area has four channels. claim 3 5. The apparatus as claimed in  claim 4  wherein the collimator furthermore has a peripheral area comprising a plurality of divergent channels making, with the channels of the central area, an angle which increases with their distance from the central area. claim 4 6. The apparatus as claimed in  claim 3  wherein the collimator furthermore has a peripheral area comprising a plurality of divergent channels making, with the channels of the central area, an angle which increases with their distance from the central area. claim 3 7. The apparatus as claimed in  claim 1 , characterized in that the plurality of means for measuring the gamma-ray flux consists of a plurality of single-anode photomultipliers capable of receiving the light signal emitted by the sensor means. claim 1 8. The apparatus as claimed in  claim 7 , characterized in that the number of photomultipliers is four. claim 7 9. The apparatus as claimed in  claim 1 , characterized in that the plurality of means for measuring the gamma-ray flux consists of a multi-anode photomultiplier. claim 1 10. The apparatus as claimed in  claim 1 , characterized in that the means for analyzing the gamma-ray flux are electronic means. claim 1 11. The apparatus as claimed in  claim 1 , characterized in that the means capable of defining the central axis of the apparatus are in the form of at least two coherent light sources generating narrow light beams, the Intersection of which corresponds to the perpendicular at the center of the sensitive area of the apparatus. claim 1 12. The apparatus of  claim 1  wherein said means for defining the central axis comprises a light rays. claim 1