Periodic Reporting for period 1 - UNICORN (Hybrid Nanocomposite Scintillators for Transformational Breakthroughs in Radiation Detection and Neutrino Research)
Reporting period: 2023-06-01 to 2024-05-31
Modern technologies with significant socio-economic impact often rely on ionising radiation detection. These include environmental and border monitoring, industrial inspection, diagnostics, precision medicine, and advanced scientific research. Effective, inexpensive, customisable, and scalable ionising radiation detection, typically using scintillator materials, is crucial across these diverse fields. However, current technologies face substantial bottlenecks. Inorganic scintillator crystals are often too expensive, fragile, slow, and difficult to scale, while plastic scintillators lack sufficient density and effectiveness.
The UNICORN project aims to overcome these challenges by introducing a new paradigm in scintillator material design: chemically synthesised scintillator nanocrystals (NCs) embedded in suitable host matrices. Leveraging the flexibility and scalability of nanochemistry, UNICORN will create innovative materials that combine the effectiveness of inorganic crystals with the versatility, scalability, and low cost of plastics. Additionally, nanoscintillators in the quantum confinement regime will unlock new physical processes unique to nanoscale, previously unexplored for radiation detection. This could make UNICORN's composite nanoscintillators greater than the sum of their parts through unprecedented application specificity.
Achieving these objectives necessitates an interdisciplinary approach, encompassing theoretical, chemical, and physical aspects. This involves addressing the fundamentals of nanoscale scintillation, as well as the synthesis and manipulation challenges of NCs in dense matrices. Specific material strategies and experimental approaches will be employed. As a case study, UNICORN focuses on homogeneous detectors for neutrinoless double beta decay (0νDBD), a rare, unobserved event that could reveal the elusive mass of neutrinos, a critical missing piece in the Standard Model.
To achieve its goals, UNICORN targets the following objectives:
-Design, synthesis, and functionalization of new NCs engineered for high-performance radiation detectors, particularly for 0νDBD.
-Incorporation of these NCs into optical-grade ultra-dense nanocomposites.
-Understanding the fundamental photophysical processes in NCs under ionizing radiation by decoupling primary and secondary excitation effects and understanding energy migration/transfer processes to suppress harmful non-radiative processes.
-Design, assembly, and testing of high-performance 0νDBD prototype detector modules with maximized light collection and energy resolution.
UNICORN's interdisciplinary approach promises to advance both technical and scientific progress by addressing the limitations of current scintillator materials and exploring new avenues in radiation detection technology.
The UNICORN project aims to overcome these challenges by introducing a new paradigm in scintillator material design: chemically synthesised scintillator nanocrystals (NCs) embedded in suitable host matrices. Leveraging the flexibility and scalability of nanochemistry, UNICORN will create innovative materials that combine the effectiveness of inorganic crystals with the versatility, scalability, and low cost of plastics. Additionally, nanoscintillators in the quantum confinement regime will unlock new physical processes unique to nanoscale, previously unexplored for radiation detection. This could make UNICORN's composite nanoscintillators greater than the sum of their parts through unprecedented application specificity.
Achieving these objectives necessitates an interdisciplinary approach, encompassing theoretical, chemical, and physical aspects. This involves addressing the fundamentals of nanoscale scintillation, as well as the synthesis and manipulation challenges of NCs in dense matrices. Specific material strategies and experimental approaches will be employed. As a case study, UNICORN focuses on homogeneous detectors for neutrinoless double beta decay (0νDBD), a rare, unobserved event that could reveal the elusive mass of neutrinos, a critical missing piece in the Standard Model.
To achieve its goals, UNICORN targets the following objectives:
-Design, synthesis, and functionalization of new NCs engineered for high-performance radiation detectors, particularly for 0νDBD.
-Incorporation of these NCs into optical-grade ultra-dense nanocomposites.
-Understanding the fundamental photophysical processes in NCs under ionizing radiation by decoupling primary and secondary excitation effects and understanding energy migration/transfer processes to suppress harmful non-radiative processes.
-Design, assembly, and testing of high-performance 0νDBD prototype detector modules with maximized light collection and energy resolution.
UNICORN's interdisciplinary approach promises to advance both technical and scientific progress by addressing the limitations of current scintillator materials and exploring new avenues in radiation detection technology.
In the first Reporting Period, UNICORN's main tasks were to delineate theoretical criteria for designing scintillator nanocrystals (NCs) using Monte Carlo and Density Functional Theory simulations (WP1) and to synthesize the first generation of scintillator NCs based on these guidelines (WP2). In-depth characterization of these NCs was essential to validate the theoretical guidelines and provide feedback for material optimization. According to the timetable, the UNICORN consortium started and addressed the first tasks under WP1-3, with WP4 planned to start in month 22.
WP1: Theoretical study of interactions between NCs and ionizing radiation using Geant4 Monte Carlo simulations.
Computational evaluation of light outcoupling aspects of dense NC-based materials using Geant4 Monte Carlo simulations.
Theoretical study of the electron and surface structure for optimizing NCs as scintillators using density functional theory (DFT).
WP2: We followed UNICORN's material strategies to produce a wide range of NC classes: We developed cadmium chalcogenide colloidal nanoplatelets with reduced self-absorption with scaling up techniques for prototype devices. UNICORN also focused on synthesizing alternative materials like oxide NCs and metal halides in perovskite phases, which were incorporated into plastic matrices. Nanomaterials via radiation synthesis and other methods were produced, including rare-earth doped low-gap metal oxides and novel multinary composites, with micro-pulling down techniques used for producing NC samples in glassy materials.
WP3: This phase dealt with the detailed characterization of materials produced in WP2 and the rationalization of their properties based on WP1 findings. We employed various spectroscopic and radiometric techniques to study emission processes under ionizing and non-ionizing excitation, comparing the linear and non-linear photophysics of nanomaterials. The role of surface and internal defects in NCs and the effectiveness of their passivation by surface reconstruction/heterostructuring were studied in detail for different material classes. Initial radiation hardness studies assessed the resistance of NCs to radiation.
This comprehensive approach in the first reporting period laid a solid foundation for subsequent phases, ensuring the theoretical and experimental aspects were aligned for optimal scintillator NC development.
WP1: Theoretical study of interactions between NCs and ionizing radiation using Geant4 Monte Carlo simulations.
Computational evaluation of light outcoupling aspects of dense NC-based materials using Geant4 Monte Carlo simulations.
Theoretical study of the electron and surface structure for optimizing NCs as scintillators using density functional theory (DFT).
WP2: We followed UNICORN's material strategies to produce a wide range of NC classes: We developed cadmium chalcogenide colloidal nanoplatelets with reduced self-absorption with scaling up techniques for prototype devices. UNICORN also focused on synthesizing alternative materials like oxide NCs and metal halides in perovskite phases, which were incorporated into plastic matrices. Nanomaterials via radiation synthesis and other methods were produced, including rare-earth doped low-gap metal oxides and novel multinary composites, with micro-pulling down techniques used for producing NC samples in glassy materials.
WP3: This phase dealt with the detailed characterization of materials produced in WP2 and the rationalization of their properties based on WP1 findings. We employed various spectroscopic and radiometric techniques to study emission processes under ionizing and non-ionizing excitation, comparing the linear and non-linear photophysics of nanomaterials. The role of surface and internal defects in NCs and the effectiveness of their passivation by surface reconstruction/heterostructuring were studied in detail for different material classes. Initial radiation hardness studies assessed the resistance of NCs to radiation.
This comprehensive approach in the first reporting period laid a solid foundation for subsequent phases, ensuring the theoretical and experimental aspects were aligned for optimal scintillator NC development.
The main objectives of the First Reporting Period were to establish theoretical and experimental foundations by developing the necessary computational codes, fabricating the first generation of scintillator NCs and nanocomposites, and performing physicochemical and radiometric characterizations to refine and optimize the materials. These activities addressed novel issues, advancing the state of the art in using confined nanoscale materials for ionizing radiation detection.
- Extensive DFT investigations calculated the electronic structure of various material systems based on Materials Strategies A, B, and C. Effects of surface states and their coordination were computed to understand and eliminate nonradiative traps. Feedback to WP2 boosted the emission properties of target NCs. A Monte Carlo code based on GEANT4 was developed an used to simulate energy containment efficiency, mean energy deposited into NCs, and light collection efficiency for representative NCs, including chalcogenide heterostructures and lead halide perovskites.
- Heterostructured colloidal CdSe-based nanoplatelets, lead halide perovskite NCs, and metal oxides (CdO) were synthesized via colloidal routes. Low-waste, high-throughput methods were developed for metal halide NCs. Radiation methods prepared narrow-gap ZnO-based and garnet-based NCs. A novel composition of Cs2TeCl6 was produced in microcrystalline powder form.
- Compatibility with plastic hosts was achieved for various NCs.
- Cerium-doped sodium-gadolinium phosphate glass was prepared using a rapid quenching technique.
- Fundamental photophysics, defect studies, and scintillation characterization for CdSe/CdS NCs identified correlations between material structure and scintillation.
- The scintillation of CsPbX3 NCs was studied in detail using synchrotron radiation.
- The multiexcitonic nature of scintillation in NCs was revealed for the first time, laying new groundwork for developing NC-based scintillators.
- The effect of polymer encapsulation on the scintillation of lead halide perovskite NCs was clarified.
- These efforts established a solid theoretical and experimental basis for advancing the UNICORN project.
- Extensive DFT investigations calculated the electronic structure of various material systems based on Materials Strategies A, B, and C. Effects of surface states and their coordination were computed to understand and eliminate nonradiative traps. Feedback to WP2 boosted the emission properties of target NCs. A Monte Carlo code based on GEANT4 was developed an used to simulate energy containment efficiency, mean energy deposited into NCs, and light collection efficiency for representative NCs, including chalcogenide heterostructures and lead halide perovskites.
- Heterostructured colloidal CdSe-based nanoplatelets, lead halide perovskite NCs, and metal oxides (CdO) were synthesized via colloidal routes. Low-waste, high-throughput methods were developed for metal halide NCs. Radiation methods prepared narrow-gap ZnO-based and garnet-based NCs. A novel composition of Cs2TeCl6 was produced in microcrystalline powder form.
- Compatibility with plastic hosts was achieved for various NCs.
- Cerium-doped sodium-gadolinium phosphate glass was prepared using a rapid quenching technique.
- Fundamental photophysics, defect studies, and scintillation characterization for CdSe/CdS NCs identified correlations between material structure and scintillation.
- The scintillation of CsPbX3 NCs was studied in detail using synchrotron radiation.
- The multiexcitonic nature of scintillation in NCs was revealed for the first time, laying new groundwork for developing NC-based scintillators.
- The effect of polymer encapsulation on the scintillation of lead halide perovskite NCs was clarified.
- These efforts established a solid theoretical and experimental basis for advancing the UNICORN project.