Gamma-KEV: Imaging the invisible

A robust sensor capable of precisely identifying the energy of, and imaging the gamma radiation field associated with radioactive material, is needed that will operate in hostile working environments. The proposed project will bring together three partners, the University of Liverpool, BAe Systems Submarine Solutions and John Caunt Scientific (JCS). The partners bring expertise in gamma-ray detector systems, packaging for robust hostile environments and marketing, respectively. This knowledge exchange project will provide BAe systems with access to the wealth of experience in high resolution gamma-ray systems available at the University of Liverpool, while allowing Liverpool to become familiar with robust packaging and testing procedures allowing them to exploit academically developed instrumentation in a 'realistic working environment'. JCS bring key marketing experience to the project, allowing the technologies to be developed to suit future customer needs based on the outcomes of this project. The aim is that the system will be a modular solution for radiation detection that can be used in a wide variety of applications (for example nuclear assay for site clearance as well as the work to be carried out here). The requirement here is for the detection and imaging of gamma radiation that may arise on a nuclear submarine. This includes both gamma radiation from the reactor derived from fission products and actinides and gammas arising from neutron scattering and activation. The requirement is to cover the 60 keV to 10 MeV gamma-ray energy range and to have an imaging capability to identify the source of the radiation in the complex submarine environment. This is likely to require an image resolution in the 5 to 10 mm range. The instrument will able to identify specific radioactive isotopes making it possible to collect useful plant state information in real-time. Measurements will be made at several locations around the boat during HMS Astute's initial criticality. The proposed instrument will provide real data on the boat to allow BAe to develop a family of Resilient Gamma Spectrometers/Imagers that could be used for further trials on UK/US submarines and can be commercially exploited by John Caunt Scientific. The instrument will be designed for optimum efficiency to image gamma-ray emissions which are of interest in a submarine environment (60 keV / 10 MeV), but in principle the instrument could be used in other applications, in particular gamma-ray detection in crime and security situations following neutron interrogation. The nuclear physics group at the University of Liverpool has an outstanding record for experimental research into the structure of nuclei. This work is underpinned by the development of state-of-the-art instrumentation which supports this physics programme. The group are world leaders in the use of Germanium semiconductor sensors with digital readout systems. The Liverpool group is leading the characterisation of highly segmented germanium detector crystals for the Advanced Gamma-ray Tracking Project (AGATA). AGATA is a large European collaboration which aims to build the ultimate gamma-ray spectrometer for nuclear structure physics applications. Gamma-ray spectrometers that can exactly identify the isotope emitting the radiation have until recently used germanium as an active sensor.