Scintillator developments for high energy physics and medical imaging

Scintillating crystals have been for a long time developed as a basic component in particle detectors with a strong spin-off in the field of medical imaging. A typical example is BGO, which has become the main component of PET scanners since the large effort made by the L3 experiment at CERN to develop low cost production methods for this crystal. Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for high energy physics and for a new generation of medical imaging devices with increased resolution and sensitivity. The examples of the lead tungstate crystal for the CMS experiment at CERN (high energy physics) as well as of new materials under development for medical imaging will be described with an emphasis on the mutual benefit both fields can extract from a common R&D effort. (14 refs)

Современные сцинтилляционные материалы для калориметрии на циркулярных коллайдерах

The most probable scenario for the development of experimental high-energy physics in the next 50 years is the creation of a family of Future Circular Colliders (FCC) at CERN, a Circular Electron–Positron Collider at China, and a Future Electron-Ion Collider at Brookhaven (USA), which continue the Large Hadron Collider (LHC) scientific program within the framework of the Standard Model and beyond it. The first generation of colliders to be put into operation will utilize the electron beam as one of the colliding species to provide precise mass spectroscopy in a wide energy range. Similarly to the measurements at the high luminosity phase of the LHC operation, the most important property of the detectors to be used in the experimental setup is a combination of the short response of the detectors and their high time resolution. The radiation tolerance to a harsh irradiation environment remains mandatory but not the main factor of the collider’s experiments using electronic beams. A short response in combination with high time resolution ensures minimization of the influence of the pile-up and spill-over effects at the high frequency of collisions (higher than 50 MGz). The radiation hardness of the materials maintains the long-term high accuracy of the detector calibration. This paper discusses the prospects for using modern inorganic scintillation materials for calorimetric detectors at future colliders.Наиболее вероятным сценарием развития экспериментальной физики высоких энергий в ближайшие 50 лет является создание семейства кольцевых коллайдеров будущего (FCC) в ЦЕРНе, кольцевого электрон-позитронного коллайдера (CEPC) в КНР и будущего электрон-ионного коллайдера в Брукхейвене (США), которые продолжают научную программу Большого адронного коллайдера (LHC) в рамках Стандартной модели и за ее пределами. Первое поколение коллайдеров, которые введут в эксплуатацию, будут использовать электроны в качестве одной из сталкивающихся частиц для обеспечения точной масс-спектроскопии в широком диапазоне энергий. Подобно измерениям в фазе высокой светимости LHC, наиболее важным свойством детекторов, которые будут применяться в экспериментальных установках, является сочетание короткого отклика детекторов и высокого временного разрешения. Радиационная стойкость в условиях радиационного фона экспериментов остается обязательной, но не основным фактором коллайдерных экспериментов с применением электронных пучков. Короткий отклик в сочетании с высоким временным разрешением обеспечивает минимизацию влияния эффектов перекрытия сигналов событий и наложения отклика детектора при высокой частоте столкновений, превышающей 50 МГц. Радиационная стойкость материалов обеспечивает долгосрочную высокую точность калибровки детектора. В настоящей статье обсуждаются перспективы использования современных неорганических сцинтилляционных материалов для калориметрических детекторов на коллайдерах будущего

Гадолиний-содержащее сцинтилляционное стекло для регистрации нейтронов в широком диапазоне энергий

Inorganic scintillation glasses form a domain of rapidly evolving detector materials used to measure various types of ionizing radiation. The most widespread are lithium-silicate glasses enriched with the 6Li isotope, which are used to register thermal neutrons. At the same time, due to the specificity of the energy dependence of the neutron cross-section of light nuclei, such materials are of little use for the evaluation of epithermal and more highly energetic neutrons. The use of rare earth elements in the composition of glasses makes it possible to increase the sensitivity to neutrons. In the BaO–Gd2O3–SiO2 system, doped with Ce ions, a scintillation glass with a yield of at least 2500 photons / MeV was created for the first time, which permits to create inexpensive detector elements of a significant volume for registering neutrons. It has been shown that a detector based on BaO–Gd2O3–SiO2 glass has satisfactory properties when detecting neutrons in a wide spectrum of their energies.Неорганические сцинтилляционные стекла формируют домен быстроразвивающихся детекторных материалов, используемых для детектирования различных видов ионизирующего излучения. Наибольшее распространение получили литий-силикатные стекла, обогащенные изотопом 6Li, которые используются для регистрации тепловых нейтронов. Вместе с тем в силу специфики энергетической зависимости сечения нейтронов легких ядер такие материалы малопригодны для регистрации эпитермальных и более высокоэнергетичных нейтронов. Использование редкоземельных элементов в составе стекол позволяет повысить чувствительность к нейтронам. В системе BaO–Gd2O3–SiO2 при активации ионами церия впервые создано сцинтилляционное стекло с выходом не менее 2500 фот/МэВ, что позволяет создавать недорогие детекторные элементы значительного объема для регистрации нейтронов. Установлено, что детекторы на основе стекла BaO–Gd2O3–SiO2 обладают удовлетворительными детекторными свойствами при регистрации нейтронов в широком спектре их энергий

Композиционно неупорядоченные активированные ионами церия кристаллы типа граната для более ярких и быстрых сцинтилляций

Ce-doped tetracationic garnets (Gd, M)3Al2Ga3O12(M = Y, Lu) form a family of new multipurpose promising scintillation materials. The aim of this work was to evaluate the scintillation yield in the materials of quaternary garnets activated by cerium ions with partial isovalent substitution of the matrix-forming gadolinium ions by yttrium or lutetium ions.Materials were obtained in the form of polycrystalline ceramic samples, and the best results were shown by samples obtained from the raw materials produced by the coprecipitation method. It was found that ceramics obtained from coprecipitated raw materials ensure a uniform distribution of activator ions in the multi-cationic matrices, which enables the high light yield and fast scintillation kinetics of the scintillation. It was demonstrated that the superstoichiometric content of lutetium/gadolinium in the material is an effective method to suppress phosphorescence accompanied scintillation. For ceramics with the composition (Gd, Lu)3Al2Ga3O12 , a scintillation yield of more than 50.000 ph/MeV was achieved. The scintillation kinetics was measured to be close to the kinetics with a decay constant of 50 ns.In terms of the set of the parameters, the developed scintillation materials are close to the recently developed alkali halide materials LaBr3:Ce, GdBr3:Ce. Moreover, they have high mechanical hardness, are characterized by the absence of hygroscopicity, and are better adapted to the manufacture of pixel detectors used in modern devices for medical diagnostics.Четырёхкатионные гранаты (Gd, M)3Al2Ga3O12(M = Y, Lu), легированные ионами Ce, формируют семейство новых многоцелевых перспективных сцинтилляционных материалов. Целью работы являлось проведение оценки выхода сцинтилляций в сцинтилляционных материалах четверных гранатов, активированных ионами церия при частичной изовалентной замене матрицеобразующих ионов гадолиния ионами иттрия или лютеция.Материалы были получены в виде поликристаллических пластин, причём наилучшие результаты показали образцы, полученные из сырья, произведённого  методом  соосаждения.  Установлено, что керамика, полученная из соосаждённого сырья, обеспечивает однородность распределения активаторных ионов в многокатионных матрицах. Это, в свою очередь, обеспечивает достижение высокого световыхода и быстрой кинетики сцинтилляции. Показано, что сверхстехиометрическое содержание лютеция/гадолиния в материале для изготовления керамики является эффективным средством подавления фосфоресценции. Для керамики состава (Gd, Lu)3Al2Ga3O12 достигнут выход сцинтилляций более 50000 фот./МэВ, а усреднённая константа затухания кинетики сцинтилляций близка к 50 нс.По совокупности параметров разработанные сцинтилляционные материалы близки к недавно разработанным щелочно-галоидным материалам LaBr3:Ce, GdBr3:Ce, к тому же обладают высокой твёрдостью, характеризуются отсутствием гигроскопичности и лучше приспособлены к изготовлению пиксельных детекторов, используемых в современных устройствах для медицинской диагностики

Advances of the Cubic Symmetry Crystalline Systems to Create Complex, Bright Luminescent Ceramics

A method to create compositionally disordered compounds with a high number of cations in the matrices, that utilize the cubic spatial symmetry of the garnet-type crystalline systems is demonstrated. Mixtures of the garnet-type powdered materials solely doped with Ce were used to create atomic compositions of high complexity. Several mixed systems, namely Gd3Al2Ga3O12/(Gd,Y)3Al2Ga3O12, Y3Al5O12/Gd3Al2Ga3O12, and Y3Al5O12/Y3Al2Ga3O12 were annealed, compacted and sintered in air. The materials were evaluated for structural, luminescence, and scintillation properties. It was demonstrated that the properties of the resulting ceramics are a little dependent on the granularity of powders when the median particle size is below ~5 μm. © 2023 by the authors.National Research Council Canada, NRC; Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-1353, 075-15-2023-370, 22.02.2023; Ural Federal University, UrFU; Ministry of Science and Higher Education of the Russian Federation: FEUZ-2023-0013The authors at NRC “Kurchatov Institute” acknowledge support from the Russian Ministry of Science and Education, Agreement No. 075-15-2021-1353. Analytical research was conducted using equipment of the «Research Chemical and Analytical Center NRC» «Kurchatov Institute» Shared Research Facilities under project’s financial support by the Russian Federation, represented by The Ministry of Science and Higher Education of the Russian Federation, Agreement No. 075-15-2023-370 dd. 22.02.2023. Authors at Ural Federal University acknowledge partial support from the Ministry of Science and Education, project No. FEUZ-2023-0013 and program of strategic academic leadership “Priority 2030”

Towards effective indirect radioisotope energy converters with bright and radiation hard scintillators of (Gd,Y)3Al2Ga3O12 family

Ceramics of quaternary garnets (Gd,Y)3Al2Ga3O12 doped with Ce, Tb have been fabricated and evaluated as prospective materials for indirect energy converters of α-and β-voltaic. Samples were characterized at excitation with an X-ray source and an intense 150 keV electron beam and showed good temperature stability of their emission and tolerance to irradiation. The role of X-rays accompanied the α-particle emitting in the increase of the conversion efficiency is clarified. The garnet-type structure of the matrix in the developed materials allows the production of quality crystalline mass with a light yield exceeding that of the commonly used YAG: Ce scintillator by a factor of two times. © 2022 Korean Nuclear SocietyMinistry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-1353, FEUZ-2020-0060; Ministerstwo Edukacji i Nauki, MNiSW: 075-11-2021-070; Ministry of Science and Higher Education of the Russian FederationAuthors with affiliations b, d, e and f acknowledge support from Russian Ministry of Science and Education grant No. 075-15-2021-1353 . The scientific equipment provided by shared research facilities “Scientific Research Analytical Center of National Research Center “Kurchatov Institute” – IREA” was used, with financial support of Russian Federation, represented by the Ministry of Science and Higher Education, agreement No. 075-11-2021-070 dated August 19, 2021. The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060 ) (authors with affiliation “c”).Authors with affiliations b, d, e and f acknowledge support from Russian Ministry of Science and Education grant No. 075-15-2021-1353. The scientific equipment provided by shared research facilities “Scientific Research Analytical Center of National Research Center “Kurchatov Institute” – IREA” was used, with financial support of Russian Federation, represented by the Ministry of Science and Higher Education, agreement No. 075-11-2021-070 dated August 19, 2021. The work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, project No. FEUZ-2020-0060) (authors with affiliation “c”)

The Saturation of the Response to an Electron Beam of Ce- and Tb-Doped GYAGG Phosphors for Indirect β-Voltaics

GYAGG:Tb (Ce) scintillators have been confirmed to be promising sources of light emission when excited by an intense 150 keV electron beam. The saturation of the scintillation yield under such excitation conditions has been studied. To explain the results obtained, a model that considers the Auger quenching mechanism was used. The Ce-doped material did not show saturation, whereas a moderate 30% drop of the yield was measured in the Tb-doped sample at the highest excitation beam intensity ~1 A/cm2. This put forward a way to exploit the Tb-doped scintillator for indirect β-voltaic batteries. © 2023 by the authors.National Research Council Canada, NRC; Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2021-1353, FEUZ 2023-0013The authors at NRC “Kurchatov Institute” and Moscow State University acknowledge support from the Russian Ministry of Science and Education, Agreement No. 075-15-2021-1353. Analytical studies have been carried out using the scientific equipment of NRC Kurchatov Institute IREA. The research at Ural Federal University was partially supported by the Ministry of Science and Higher Education of the Russian Federation (Project FEUZ 2023-0013)