Fast Neutron Imaging with Semiconductor Nanocrystal Scintillators
Kyle McCall a b, Kostiantyn Sakhatskyi a b, Eberhard Lehmann c, Bernhard Walfort d, Adrian Losko e, Federico Montanarella a b, Maryna Bodnarchuk a b, Franziska Krieg a b, Yusuf Kelestemur a b f, David Mannes c, Yevhen Shynkarenko a b, Sergii Yakunin a b, Maksym Kovalenko a b
a Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg, 1, Zürich, Switzerland
b Laboratory for Thin Films and Photovoltaics, Empa—Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse, 129, Dübendorf, Switzerland
c Paul Scherrer Institut, Villigen PSI, 5232, Switzerland, Forschungsstrasse 111, Villigen, Switzerland
d RC Tritec Ltd., Teufen, 9053, Switzerland, Speicherstrasse, 60A, Teufen, Switzerland
e Forschungs-Neutronenquelle Heinz Maier-Leibnitz, Garching, 85748, Germany
f Department of Metallurgical and Materials Engineering, Atilim University, Ankara, 06830, Turkey
Proceedings of Internet NanoGe Conference on Nanocrystals (iNCNC)
Online, Spain, 2021 June 28th - July 2nd
Organizers: Maksym Kovalenko, Maria Ibáñez, Peter Reiss and Quinten Akkerman
Oral, Kostiantyn Sakhatskyi, presentation 024
DOI: https://doi.org/10.29363/nanoge.incnc.2021.024
Publication date: 8th June 2021

Fast neutrons offer high penetration capabilities for both light and dense materials due to their comparatively low interaction cross sections, making them ideal for the imaging of large-scale objects such as large fossils or as-built plane turbines, for which X-rays or thermal neutrons do not provide sufficient penetration. However, inefficient fast neutron detection limits widespread application of this technique. Traditional phosphors such as ZnS:Cu embedded in plastics are utilized as scintillators in recoil proton detectors for fast neutron imaging. However, these scintillation plates exhibit significant light scattering due to the plastic–phosphor interface along with long-lived afterglow (on the order of minutes), and therefore alternative solutions are needed to increase the availability of this technique. Here, we utilize colloidal nanocrystals (NCs) in hydrogen-dense solvents for fast neutron imaging through the detection of recoil protons generated by neutron scattering, demonstrating the efficacy of nanomaterials as scintillators in this detection scheme. The light yield, spatial resolution, and neutron-vs-gamma sensitivity of several chalcogenide (CdSe and CuInS2)-based and perovskite halide-based NCs are determined, with only a short-lived afterglow (below the order of seconds) observed for all of these NCs. FAPbBr3 NCs exhibit the brightest total light output at 19.3% of the commercial ZnS:Cu(PP) standard, while CsPbBrCl2:Mn NCs offer the best spatial resolution at ∼2.6 mm. Colloidal NCs showed significantly lower gamma sensitivity than ZnS:Cu; for example, 79% of the FAPbBr3 light yield results from neutron-induced radioluminescence and hence the neutron-specific light yield of FAPbBr3 is 30.4% of that of ZnS:Cu(PP). Concentration and thickness-dependent measurements highlight the importance of increasing concentrations and reducing self-absorption, yielding design principles to optimize and foster an era of NC-based scintillators for fast neutron imaging.

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