Periodic Reporting for period 1 - NASCAR (NAno SCintillator ARrays (NASCAR) as a Novel Nuclear Detection Material)
Berichtszeitraum: 2021-12-15 bis 2023-12-14
Detection of special nuclear materials (SNM), is of vital importance to prevent nuclear terrorism and to secure states’ national security. Neutron detection is a particularly useful tool to identify SNM and neutron-sensitive scintillators have many promising properties, such as ease of use, good time resolution, and high detection efficiency. In this project we develop a new state-of-the art neutron sensitive scintillator using on nanostructured scintillating materials. A Li (or B) incorporated nanostructured ZnO devices were proposed for highly efficient thermal neutron detection. These devices use a novel nanorod array design that greatly increases the effective surface area and efficiency of the sensor. Cost effective low temperature hydrothermal growth is used to obtain ZnO nanorod arrays. The state-of-the-art design of the nanorod array combines the key advantages of a low cost growth technique together with environmentally friendly and widely available materials.
In this report period, ZnO nanoarrays were grown via a low temperature hydrothermal method. The effects of the additives involved in the growth procedure i.e. ammonium hydroxide and sodium citrate were studied in terms of the morphological, optical and the scintillation properties of the ZnO nanostructures. ZnO NRs grown on a silica substrate showed high quality structural and optical properties. The addition of sodium citrate was found to reduce defects significantly and correspondingly increased the intrinsic near-band edge (NBE) UV emission intensity at ~380 nm. Annealing in a 10% H2 + 90% N2 atmosphere was performed to obtain high quality nanostructures. Highly tapered NRs were obtained towards the end of the structure. Time growth studies were conducted to monitor the tapering process and the tapering effect on photoluminescence (PL) as well as reflectance spectra were presented. Tapered ZnO NRs showed excellent anti-reflection properties. As grown ZnO NRs were found to have high alpha particle responses. ZnO NRs were then doped with Al, Ga and In and the structural, optical and scintillation properties were monitored. It was seen that optical and scintillation properties were improved by doping ZnO NRs. Studies are now directed to the growth of vertically well-aligned dense ZnO NR arrays doped with 6Li, which will serve as radiators that the thermal neutrons will interact. In addition, simulation studies on optical and scintillation properties are in progress.
While vertically grown ZnO NRs are available in the literature, we were able to grow tapered vertically well-aligned ZnO NR arrays for the first time which increase light absorption and optical coupling resulting in enhanced scintillation properties. Therefore, obtaining tapered NR arrays contributed to the state of the art in the project. The 6Li incorporated ZnO NRs which will be obtained using low temperature hydrothermal method will increase thermal neutron sensitivity, which is a milestone in the project.