Laboratory for Luminescent and Detector Materials

• Using nuclear physical modeling we have determined that that materials containing Gd, Y, Li, B, Be ions are optimal for creation of scintillators to detect neutrons in a wide range of energies by registering products of interaction in the form of charged particles and low-energy gamma quants
• Experiments have shown that binary systems based on silicon and elements from the second group after their activation by cesium ions do not show high scintillation output. Introduction of gadolinium ions to composition of glasses increases scintillation output even in calcium-based systems having output close to zero, however, it does not radically increase its value. This is caused by the fact that in glass only a portion of Ce ions for which there are favorable conditions for capturing free charge carriers leads to scintillations. In this context crystalline systems also become an object of further research as systems providing the highest scintillations output.
• We have demonstrated usage of Tb3+ ions as activator ions in binary systems allows to increase scintillations output up to 30000 photons per MeV. This is caused by features of excitation of f-f radiative transitions in disorganized systems
• We have observed stability of silicate lithium-beryllium glasses with 29 mole percent concentration of beryllium if the glass is doped with cesium ions. Scintillations output of such glass is up to 400 photons per neutron, However, as modeling suggests, concentration of beryllium in slilcate glass should be at least twice higher for effective moderation of neutrons. Increase of beryllium concentration leads to liquation of glass melt.
• Our team has performed quantitative modeling of passage of neutrons through substances with different compositions, efficiency of their registration and spectrums of products of interaction using the GEANT4 software package. We have found good coincidence between results of modeling and both experimental results of registering Am-Be neutrons by developed scintillators and with results obtained using other software packages.
• By modeling and subsequent measurement of neutrons using the Gd3Al2Ga3O12:Ce scintillator we have determined presence of intense lines of gamma quants with energies 90, 190 and 511 keV whose amplitudes depend on energies of neutrons in spectrums of products of interaction between neutrons and gadolinium nucleus. The results of comparing calculated and measured spectrums of soft gamma-quants allowed to propose a patent for a new method of and a device for neutron registration based on gadolinium-containing scintillator material.
• Same detecting characteristics have been shown for ceramic materials of similar composition
• We have successfully approbated a set of methods of purification of lithium compounds from various contaminants up to a sufficient level of purity. The research has shown that extraction of lithium from waste and defective products is possible but it becomes reasonable only upon increasing weight of processed material to several kilograms.
• In furnaces with heating based on gas burners and resistive heating we have obtained samples that can compete with industrially produced scintillators of similar composition.
• Examples of binary glasses in Сa-Si, Sr-Si, Ba-Si, Li-Si systems have shown that re-melting the glass in air atmosphere leads to shift in balance of charge states in Ce3+ / Ce4+ and Tb3+ / Tb4+ pairs towards the 4-valent options. Thus, usage of activated frit to produce glass has not demonstrated obvious technological advantages compared to producing glass from batch
• We have demonstrated characteristics of materials based on complex oxides with granat structures that allow to consider them for registering neutrons in accelerators – high resistance to radiation and possibility of reaching low times of time matches.

• A new type of materials in the field of neutron detection is proposed – scintillators based on crystalline oxides with a garnet structure (Gd,Y)₃(Ga,Al)₅O₁₂:Ce. An original solution for detection of neutrons using this material is proposed (patented by NRC "Kurchatov Institute"), and prototypes of detectors have been created to demonstrate the efficiency of the concept. Furthermore, the physics and chemistry of this class of materials were studied, and the materials with competitive detector properties have been obtained. The potential of this material for the creation of short-base time-of-flight neutron detectors has been demonstrated. A principal design of an antineutrino detector using the advantages of the materials under study has been proposed and patented.

• Techniques have been developed and laboratory samples of the materials have been obtained of scintillation glasses: Li₂O-SiO₂:Ce – the classical material for thermal neutron detection – having working characteristics competitive to those known from the literature; Li₂O-SiO₂:Tb – a scintillator for registration of thermal neutrons with a high light yield; BaO-Gd₂O₃-SiO₂:Ce – a promising scintillator for large volume detectors. Techniques have been developed and samples of scintillation pigment screens have been obtained, which combine the absorption efficiency of classical screens based on Gd₂O₂S:Tb with a fast decay and the ability to operate in a counting mode.

Implemented results of research:

• The developed methods and detector modules can be used in research equipment, neurograph devices, devices for controlling propagation of fissioning materials. At the moment, the project is at the research stage, development of solutions ready for industrial implementation is not planned.

• A prototype of a compact universal detecting module of an amplitude detector, adapted for neutron detection in the particle counting mode. Originally created to detect neutrons, it could be adapted to detect other types of radiation by replacing the detector material element and modifying the background radiation shielding. It undergoes tests in order to determine application niches currently.

• A prototype of a compact universal detecting module of a timing detector, adapted for neutron detection. Originally created to detect neutrons, it could be adapted to detect other types of radiation by replacing the detector material element and modifying the radiation shielding. It undergoes tests in order to determine application niches currently.

• A prototype of a section of an antineutrino detector. The original working method was developed (patented), as well as the design, and prototyping is currently underway. In case of successful tests, the detector can become a valuable research tool, and it can also be used to create remote control systems for nuclear reactors, which are driving increasing interest in the world.

Education and career development:

• 4 postgraduate students conduct their research in the area of studies of the Laboratory – luminescent materials and materials for optics

Organizational and structural changes:

During development of the project we have created a basis for measurement and research of scintillation characteristics

Other results:

Patent Application in Russia: RU 2017141977: Method of registering neutrons and a device for its implementation. Mikhaiv V. Korzhik, Andrey A. Fyodorov, Vitalit A. Mechinskiy, Alexey E. Dosovitskiy, Georgiy A. Dosovitskiy. Patent date 01.12.2017.

Collaborations:

• Crystal Clear Collaboration (RD18), CERN, Switzerland. The collaboration coordinates and performs multidisciplinary research in detector materials and techniques, including coordination of R&D on materials selection for experiments on Large hadron collider and future cicular colliders at CERN. – Joint research on CERN facilities, including radiation hardness tests and experiments, using accelerator-based neutron source; joint research, involving other collaboration members. – 5 co-authored papers were published.

• Institute for Nuclear Problems of Belarusian State University, Republic Belarus. – Joint research with home institute of the leading scientist. – More than 10 co-authored papers were published.

• Institute of Photonics and Nanotechnology, Vilnius University, Lithuania. – Joint research on fast phenomena dynamics within the luminescence process; local luminescent properties of materials. – 5 co-authored papers were published. Leading scientist co-authored a book with the professor from Institute of Photonics and Nanotechnology.

• 2-nd Physical Institute, Giessen university, Germany. – Joint research on measurements using the institute's neutron source. – 4 co-authored papers were published.

• Technical University of Darmstadt, Germany. – Collaboration is under development on heavy ion beam tests of the developed materials on GSI facilities as potential beam monitors. – An application for joint RSF – DFG grant is submitted.

• Chair of experimental physics, Ural Federal University, Russia. – Joint research on radioluminescence and cathodoluminescence measurements. – First experiments were performed.

• Atomtex SPE, Republic Belarus. – Joint research on measurements using the organization's certified neutron measurement set-up. – 1 co-authored paper was published.

• Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Russia. – Joint research on the scintillator development with fast timing; application of the developed detector materials and techniques for space measurements. – Leading scientist co-authored a book with the professor from SINP MSU. 1 co-authored paper was published. A research program for a joint project is developed.

• Faculty of Chemistry, Lomonosov Moscow State University, Russia. – Summer industrial internship for the students. – 3 students have carried out their internship dealing with the lab research areas.

• Mendeleev University of Chemical Technology of Russia, Russia. – Internship for the students and diploma scientific advising. – 3 students have defended their diplomas (with «excellent» grade) dealing with the lab research areas.