Patent ID: 8247776

Claim:
A device for detecting orientation of a radioactive material to determine presence and position of the radioactive material, comprising: at least one first radiation detector; at least one second radiation detector, each of said at least one second radiation detector and each of said at least one first radiation detector being arranged side by side and in pairs, detection surfaces, which are surfaces where the rays to be detected enter the radiation detector, of said first and second radiation detector being in the same plane to receive rays from the same direction in the same manner and to generate a first detection signal and a second detection signal, respectively, and portions of said first and second radiation detectors except the detection surfaces being enclosed by shielding material, so that the rays enter the first or second radiation detectors only from the detection surfaces; a shielding plate arranged between said first radiation detector and said second radiation detector arranged in pairs and extending forward beyond said detection surfaces; and a determination device configured to receive the first and second detection signals from said first and second radiation detector, and determine whether a radioactive material exists or not from said first and second detection signals and simultaneously determine the orientation of the radioactive material according to the difference between said first detection signal and said second detection signal; wherein when the difference between the first and second detection signals is a positive value, it is determined that the radioactive material is located at the side where the first radiation detector is mounted, and when the difference between the first and second detection signals is a negative value, it is determined that the radioactive material is located at the other side where the second radiation detector is mounted.