Directional Assessment of Radiation Sources

Radiation, despite being a natural phenomenon, is widely regarded as dangerous to the human population and the environment in general. Radiation sources can be natural, e.g. due to the local geology, building material used in the construction of housing or cosmic radiation, or artificial like the radiation generated by nuclear power plants or employed in medical procedures. A threat from radiation can be classified twofold - the direct physical harm due to over-exposure to ionising radiation and the detrimental health effect due to stress of being in an unknown radiation environment. Related to the latter, it is worth mentioning the latent threat posed by criminal activity, e.g. dirty bombs or orphaned radioactive materials.

In all these cases, a rapid and reliable location and identification of the radiation sources and an evaluation of the radiation field and its associated risks can greatly help to mitigate the aforementioned detrimental effect, either by providing correct information of by guiding the emergency and post-emergency response to a radiation threat. A case in point for the latter would be the evaluation of remediation efforts in Japan in the aftermath of the Fukushima accident.

The proposed sensor will provide a compact, low-power system to be employed on the ground. It will be easily transportable, e.g. in a backpack and assess the isotopic composition and directionality of a radiation field directly and in real time. More basic systems are already in use in backpacks, car-borne surveys or lightweight drones, but crucially lack the directional sensitivity the proposed technology adds.

The proposed aims are achieved by a combination of a high-density inorganic scintillation crystals frequently used in medical imaging, combined with a compact, highly segmented photon sensor system based on silicon which only recently became technologically mature enough to be considered for these applications.

The proposal aims at developing a demonstrator of an affordable gamma-radiation sensor system with directional sensitivity. Such a system can be invaluable in the assessment of a three dimensional radiation field in the environment, the aftermath of nuclear accidents, the assessment of nuclear installation, nuclear decommissioning, nuclear threat protection and potentially medical imaging applications.

As such, the beneficiaries from this research are potentially widespread - from the UK nuclear industry and the UK nuclear decomissioning authority to a much wider use across the nuclear industry, including a significant number of ODA countries with nuclear installation or Uranium mining. Furthermore, as the proponents own experience has shown, it will be highly beneficial in the assessment of environmental impact from planned or accidental releases of radiation into the environment and the assessment and validation of remediation efforts. The compact size, projected low power consumption, directional capability with spectroscopic information will make it an ideal tool to replace common ground based systems.

The proposed technology is easily adaptable to the location and identification of orphan radioactive sources or the detection and location of special nuclear materials and hence has potential applications in nuclear threat detection or monitoring illegal proliferation.

Last not least it should be noted that the proposed technology can equally enhance medical imaging modalities like PET and SPECT by improving the location information on the detector gamma ray emitted by a radiotracer.

This proposal only aims at developing a demonstrator to prove the technology and its use using established controlled standards. It will form the basis of future development in close collaboration with the sensor industry and governmental, academic and industrial stakeholders, with whom preliminary contacts are already established.