E!10978 A Novel Dual Neutron Gamma Sensor

Detection of gamma and neutron radiation is important for monitoring of nuclear facilities and processes especially to prevent radioactivity from being dispersed in nature. We have in the NGSduo project developed a radiation detector sensitive for both gamma and neutron radiation with the capability of distinguishing between these two different types of radiation. Since neutrons do not have electrical charge they are difficult to detect. Commonly used detectors are based on a rare isotope of helium, 3He, which is not found naturally on earth but which is a byproduct in the manufacture of nuclear weapons. 3He is therefore not available as a usual commodity. An important factor is therefore to provide detectors that are indepenendt of 3He. The NGSduo product is such a detector.

We have achieved: 1: Development of. a high resolution room temperature operation gamma ray spectrometer 2: We have developed a prototype neutron and gamma ray spectrometer based on the technology from 1 3: The operation of the gamma ray and neutron spectrometers have been demonstrated under lab conditions 4: A filed trial demonstrator was developed, but not yet tested under realistic conditions 5: Imaging and reconstruction software were developed, but not yet demonstrated under realistic conditions. 6: The gamma spectrometer has been commercialised as an spectroscopic imaging core and is an active product of Integrated Detector Electronics AS

a)Our project is driven by both a commercial and a legislative needs which we see as a significant opportunity toourselves andour current and perspective partners. Traditionally neutrons have been detected using 3He gas in Geiger-Muller tubes. 3He is extremely rare on the earth surface and has been available almost exclusively as a byproduct of the manufacture of nuclear weapons using tritium. 3He is the decay product of Tritium. For this reason, 3He is not a traded product and is strictly controlled by governments. Recent reductions to the nuclear weapons arsenals have led to the notion that the existing supplies of 3He are falling down rapidly and there is a recognised legislative needin Europe and the USA to find a suitable substitute. Our approach is to build on the success of our most current instrument, the ComptonVision (developed with the help of the Eurostars program).ComtonVision combines the best available room temperature detectors with electronic trough the Compton effectbased on the use of CZT (Cadmium Zinc Teluride).CZT is a semi-conductor crystal that has the advantage of being able to produce very accurate sensors in terms of spectral resolution (<1% @662 keV) without requiring cryogenic cooling, which is required by competitive technologies e.g. high purity germanium sensors.This gives the instrument excellent isotope identification properties combined with location and dose rate information. Adding neutron detection capability to the instrument expands its usability for the customers as they now also will be able to detect also fissile materials.