Year
2017
Abstract
Within the past decade a significant shortage of 3He has occurred. Since this material is widelyused in neutron detection applications, e.g. by first responders, during on-site inspections, and insafeguard applications where nuclear and radioactive material has to be localized and possiblyidentified, replacement materials need to be considered, selected, implemented in acorresponding detector, and thoroughly tested.One of these promising materials is 6Li which is utilized in detector applications suchas 6LiF/ZnS, CLYC (Cs2LiYCl6:Ce), and CLLB (Cs2LiLaBr6:Ce). The latter two detector typeseven offer the possibility of measuring gamma radiation simultaneously with gooddiscrimination capability between neutrons and gammas. Within the detection materialsneutrons are captured by 6Li, triggering the nuclear reaction 6Li(n,t)α. The secondary particlesthen create light pulses in the scintillation crystal which ultimately serve as detection signals.Due to the large Q-value of the reaction of 4.78 MeV, the signals are of the same order ofmagnitude as those of high energetic gamma photons. The discrimination of neutron and gammaradiation can be realized by pulse shape analysis.Measurements with all detector types mentioned above have been performed. We have verifiedthese detectors’ capabilities with measurements of several neutron sources, also compared to adetector filled with 3He. The possibility of detecting such a (hidden and/or shielded) sourcewhich creates a radiation field only slightly above the background radiation level is of particularinterest. Other figures of interest were the FWHM (full width at half maximum) of the CLYCand CLLB gamma spectra and the detectors’ efficiencies, especially with regard to a detectorwith 3He tubes. The results of these verification tests will serve as supportive information forfirst responders and other experts who work in the field of nuclear safety and security regardingsuitable neutron detection materials without the rare 3He.