AUTONOMOUS ROBOTIC DETECTION OF RADIOISOTOPES BY HIGH PURITY GERMANIUM DETECTOR

摘要

The use of High Purity Germanium (HPGE) detectors for identifying radio-isotopes with Gamma RaySpectroscopy is well established. By analyzing the frequency of the incoming gamma radiation, it ispossible to identify which isotope emitted it. There are several commercially available units capable ofgiving a human continuous updates to aid searching a room. However, the vast majority of these systemsare dependent on the human user’s ability to zero in on the location of the source. This project hasintegrated a commercially available HPGE system with a robotic base which is able to track its positionwithin a room. The robot has been programmed to be able to automatically calculate the bearing of aradio-isotope source by slowly rotation on the spot and measuring the Q value calculated by ORTEC’sisotope identification program. By recoding the Q value of every isotope on each bearing and analyzingthe results in MATLAB, it is possible to calculate the peak and thus the direction of the source. The robotcan then be remotely moved to another spot in the room to repeat the process. With three bearings to thesource, this robot can then triangulate the position of the source and report this to the handler. Theprogram is able to track multiple different sources at once, allowing for the whole room to be searchedwith only a few readings. This is the first time that isotope-specific data has been directly analyzed by amachine to find meaning full conclusions. With this step completed it is only a matter of extension tocreate an entirely autonomous robot, capable of searching a room and locating all sources to within acertain statistical certainty. During the process, some unexpected properties of the sensor have beenfound which will be explained in full in the paper.