Periodic Reporting for period 2 - NASCAR (NAno SCintillator ARrays (NASCAR) as a Novel Nuclear Detection Material)
Okres sprawozdawczy: 2023-12-15 do 2024-12-14
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 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.
The results in this work demonstrated that the low temperature hydrothermal method is a simple and effective way of fabricating vertically well-aligned ZnO NRs which are well-suited for high scintillation properties. Donor doping of ZnO nanorod arrays along with optimization of additive concentrations in the solution resulted in enhanced UV emission properties. The optimized scintillator design improved thermal neutron response of the ZnO:Li nanorod arrays. Together with the superior scintillation properties including sub-nanosecond decay time, these results indicate that ZnO nano scintillators could be a good candidate for fast alpha particle scintillator screens.
The results in this work demonstrated that the low temperature hydrothermal method is a simple and effective way of fabricating vertically well-aligned ZnO NRs which are well-suited for high scintillation properties. Donor doping of ZnO nanorod arrays along with optimization of additive concentrations in the solution resulted in enhanced UV emission properties. The optimized scintillator design improved thermal neutron response of the ZnO:Li nanorod arrays. Together with the superior scintillation properties including sub-nanosecond decay time, these results indicate that ZnO nano scintillators could be a good candidate for fast alpha particle scintillator screens.
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. For the final report period, ZnO NR scintillators were first doped with enriched 6Li isotope, which acted as a radiator layer for alpha particles. Initial measurements on thermal neutron detection showed a thermal neutron response, which is a milestone in the project. Studies were then directed to advanced simulation using SRIM software to optimize the scintillator thickness and high doping of 6Li in ZnO NR structures to improve the thermal neutron response. The optimized scintillator design resulted in improved thermal neutron response of the ZnO:Li NR arrays, which is a breakthrough in the literature as the thermal neutron detection properties have not been reported for hydrothermally grown ZnO:Li NR arrays yet.
Vertically well-aligned tapered ZnO NR arrays with enhanced light absorption and optical coupling were grown in this project. The novel design of this ZnO NR arrays led to improved structural, optical, and scintillation properties.The alpha particle response obtained in thermal neutron measurements is a milestone in the project and constitutes first time measurements in the literature to the best of our knowledge. The optimized scintillator design resulted in improved thermal neutron response of the ZnO:Li NR arrays, which is a breakthrough in the literature as the thermal neutron detection properties have not been reported for hydrothermally grown ZnO:Li NR arrays yet. Results of the project were presented in an international conference and in a seminar at the host institution, and also were published in a SCI indexed journal. The researcher was involved in external collaborations and this collaboration resulted in publication of an article in a SCI indexed journal as well. The latest results of the project were submitted in a journal, which is in process.
Vertically well-aligned tapered ZnO NR arrays with enhanced light absorption and optical coupling were grown in this project. The novel design of this ZnO NR arrays led to improved structural, optical, and scintillation properties.The alpha particle response obtained in thermal neutron measurements is a milestone in the project and constitutes first time measurements in the literature to the best of our knowledge. The optimized scintillator design resulted in improved thermal neutron response of the ZnO:Li NR arrays, which is a breakthrough in the literature as the thermal neutron detection properties have not been reported for hydrothermally grown ZnO:Li NR arrays yet. Results of the project were presented in an international conference and in a seminar at the host institution, and also were published in a SCI indexed journal. The researcher was involved in external collaborations and this collaboration resulted in publication of an article in a SCI indexed journal as well. The latest results of the project were submitted in a journal, which is in process.
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 optimized scintillator design resulted in improved thermal neutron response of the ZnO:Li NR arrays, which is a breakthrough in the literature as the thermal neutron detection properties have not been reported for hydrothermally grown ZnO:Li NR arrays yet.