New microfocus bremsstrahlung source based on betatron B-18 for high-resolution radiography and tomography

New microfocus source of hard bremsstrahlung (photon energy > 1 MeV), based on the betatron B-18 with a narrow Ta target inside, for high-resolution radiography and tomography is presented. The first studies of the source demonstrate its possibilities for practical applications to detect the microdefects in products made from heavy materials and to control gaps in joints of parts of composite structures of engineering facilities. The radiography method was used to investigate a compound object consisting of four vertically arranged steel bars between which surfaces were exposed gaps of 10 [mu]m in width. The radiographic image of the object, obtained with a magnification of 2.4, illustrates the good sensitivity of detecting the gaps between adjacent bars, due to the small width of the linear focus of the bremsstrahlung source

Next-generation ultra-compact calorimeters based on oriented crystals

Calorimeters based on oriented crystals provide unparalleled compactness and resolution in measuring the energy of electromagnetic particles. Recent experiments performed at CERN and DESY beamlines by the AXIAL/ELIOT experiments demonstrated a significant reduction in the radiation length inside tungsten and PbWO4, the latter being the scintillator used for the CMS ECAL, observed when the incident particle trajectory is aligned with a lattice axis within ∼1∘. This remarkable effect, being observed over the wide energy range from a few GeV to 1 TeV or higher, paves the way for the development of innovative calorimeters based on oriented crystals, featuring a design significantly more compact than currently achievable while rivaling the current state of the art in terms of energy resolution in the range of interest for present and future forward detectors (such as the KLEVER Small Angle Calorimeter at CERN SPS) and source-pointing space-borne γ-ray telescopes

Low-Temperature Properties of the Sodium-Ion Electrolytes Based on EC-DEC, EC-DMC, and EC-DME Binary Solvents

Sodium-ion batteries are a promising class of secondary power sources that can replace some of the lithium-ion, lead–acid, and other types of batteries in large-scale applications. One of the critical parameters for their potential use is high efficiency in a wide temperature range, particularly below 0 °C. This article analyzes the phase equilibria and electrochemical properties of sodium-ion battery electrolytes that are based on NaPF6 solutions in solvent mixtures of ethylene carbonate and diethyl carbonate (EC:DEC), dimethyl carbonate (EC:DMC), and 1,2-dimethoxyethane (EC:DME). All studied electrolytes demonstrate a decrease in conductivity at lower temperatures and transition to a quasi-solid state resembling “wet snow” at certain temperatures: EC:DEC at −8 °C, EC:DMC at −13 °C, and EC:DME at −21 °C for 1 M NaPF6 solutions. This phase transition affects their conductivity to a different degree. The impact is minimal in the case of EC:DEC, although it partially freezes at a higher temperature than other electrolytes. The EC:DMC-based electrolyte demonstrates the best efficiency at temperatures down to −20 °C. However, upon further cooling, 1 M NaPF6 in EC:DEC retains a higher conductivity and lower resistivity in symmetrical Na3V2(PO4)3-based cells. The temperature range from −20 to −40 °C is characterized by the strongest deterioration in the electrochemical properties of electrolytes: for 1 M NaPF6 in EC:DMC, the charge transfer resistance increased 36 times, and for 1 M NaPF6 in EC:DME, 450 times. For 1 M NaPF6 in EC:DEC, the growth of this parameter is much more modest and amounts to only 1.7 times. This allows us to consider the EC:DEC-based electrolyte as a promising basis for the further development of low-temperature sodium-ion batteries

Microelements in river water of mountain-forest basins (Southern Russian Far East)

Актуальность: Изучение миграции растворенных химических элементов в составе речных вод в зоне их формирования в горно-лесных ландшафтах. Цель: выявление диапазонов концентраций микроэлементов в водах фоновых рек начальной гидрологической сети, определение вероятных путей их геохимической миграции. Объекты: река Правая Соколовка (система верховьев Уссури) и четыре ее притока. Методы. Концентрации микроэлементов и редкоземельных элементов определялись методом ICP-MS на приборе Agilent 7700 х (Agilent Techn., США). Содержание главных анионов (Cl-, SO42-, NO3-) определялось на жидкостном хроматографе Shimadzu LC 10Avp, главных катионов (Ca2+, Mg2+, K+, Na+) - на атомно-абсорбционном спектрометре Shimadzu AA 6800; растворенного органического углерода (РОУ) - с помощью ТОС-анализатора (Shimadzu TOC-VCPN). При обработке количественных данных использовали статистические методы анализа. Результаты. Комплексные гидрохимические исследования на пяти модельных водосборах, расположенных в среднегорном поясе Южного Сихотэ-Алиня, проведены в теплый период 2012, 2019 и 2020 гг. В пробах речной воды были определены основные компоненты химического состава, содержание «растворенных», а по существу суммы растворенных и коллоидных форм (фракция <0,45 мкм) микроэлементов. Анализ более 80 проб позволил оценить пространственно-временную вариабельность измеренных концентраций микроэлементов и установить вероятные факторы, способствующие их переносу в пределах малых водосборов с различной ландшафтной структурой. Сравнение полученных средних концентраций микроэлементов с соответствующими величинами условно чистых рек Сихотэ-Алинской горной области и мировым стоком показало сходный уровень их содержания. В целях установления совместно мигрирующих элементов и возможных компонентов, контролирующих поступление микроэлементов в речные воды, был проведен сопряженный корреляционный анализ массива данных их макрокомпонентного и микроэлементного состава. Установлено, что концентрации слабоподвижных (Al, Sc, Ga, Y, Zr, Hf, редкоземельных элементов), некоторых катионогенных (Fe, Mn, Co) и анионогенных (Se, V, Ge) микроэлементов в речных водах прямо связаны с содержанием растворенного органического углерода. Это предполагает, как одновременную миграцию органического углерода и связанных с ним элементов c водосборной площади во время выпадения интенсивных дождей, так и нахождение некоторой доли элементов в составе комплексов с органическими компонентами. Предварительный анализ особенностей режима увлажнения и ландшафтной структуры водосборов выявил тенденции межгодовой изменчивости растворенных форм Fe и Al в водах рек, дренирующих водосборы с различной структурной организацией лесных экосистем. Показано, что распространение в бассейнах горно-таежных почв, сформированных под темнохвойными лесами, обусловливает наименьшую сезонную и межгодовую изменчивость «растворенных» форм типоморфных элементов, а также их более стабильную связь с органическим углеродом. В случае доминирования в бассейнах хвойно-лиственных экосистем сезонная и межгодовая изменчивость содержания «растворимых» форм Fe и Al, проходящих через фильтр 0,45 мкм, выражена наиболее контрастно. Концентрация Fe и Al во фракции <0,45 мкм обратно пропорциональна кислотности речных вод, вариабельность которой связана с процессами аккумуляции и вымывания органических веществ из почвы.Relevance: study of the migration of chemical elements from mountain-forest ecosystems into rivers in the runoff formation zone. Purpose: assessment of microelements content and the ranges of their variability in the water of background streams at mountainous headwaters, and detecting the probable pathways and mechanisms of their geochemical migration. Objects: Pravaya Sokolovka R. (the Ussuri R. system) and its four tributaries. Methods. The concentrations of trace elements and rare earth elements were determined by ICP-MS Agilent 7700 x (Agilent Techn., USA). The content of the main anions (Cl- , SO42 - , NO3 - ) was determined on a Shimadzu LC 10Avp liquid chromatograph, the main cations (Ca2+ , Mg2+, K+ , Na+ ) - on a Shimadzu AA 6800 atomic absorption spectrometer; dissolved organic carbon (DOC) - using a TOC analyzer (Shimadzu TOC-VCPN). When processing quantitative data, the standard statistical methods of analysis were used. Results. During the warm period in 2012, 2019 and 2020, there were carried out the integrated hydrochemical studies at five research catchments located in the middle mountain belt of the Southern Sikhote-Alin. In river water samples, the main chemical components and the microelements dissolved forms were determined. The analysis of about 80 samples made it possible to assess the spatialtemporal variability of the measured concentrations of trace elements and to establish the probable factors driving their migration in small river catchments differing in landscape patterns. A comparative analysis of found trace elements concentrations showed their similar relevant values for conventionally clean rivers of the Sikhote-Alin mountain country and over the world. To reveal possible mechanisms of microelements migration into rivers, the authors accomplished a conjugate correlation analysis for the dataset of macrocomponent and microelement composition of the river water. We assumed that during rainfall events, the leaching of dissolved organic carbon and related elements from soil cover is the main mechanism for concentrating low-mobile (Al, Sc, Ti, Cr, Ga, Y, Zr, Hf, and Rare Earth Elements), some heavy (Fe, Mn, and Co), and anion-generating (Cr, Se, V, and Ge) trace elements. This suggests the migration of organic carbon and related elements from the catchment during heavy rains and the simultaneous presence of a certain proportion of elements in the composition of complexes with organic matter. A preliminary analysis of the peculiarities of the moistening regime and the landscape structure of watersheds revealed trends in the interannual variability of dissolved forms of Fe and Al in the rivers draining watersheds with the different structural organization of forest ecosystems. It is shown that the distribution of mountain taiga soils in river basins determines the lowest seasonal and interannual variability of dissolved forms of typomorphic elements, as well as their more stable relationship with organic carbon. In the case of dominance of coniferous-deciduous ecosystems in a catchment, the content of Fe and Al soluble forms depends on river water acidity, which varies associated with the processes of organic substances accumulation and leaching from the soil

Enhanced electromagnetic radiation in oriented scintillating crystals at the 100-MeV and sub-GeV scales

Nowadays, it is well known that the electromagnetic interaction between high-energy particles and matter experiences substantial modifications when the latter consists of a crystalline medium and its lattice axes are almost parallel to the input beam direction. In particular, a strong boost to the cross section of bremsstrahlung by electrons and positrons in high-density oriented crystals has been observed in the $10$-to-$100~mathrm{GeV}$ regime. This effect proves particularly appealing when it comes to inorganic scintillators, given the possibility to exploit it for the development of high-performance, ultra-compact electromagnetic calorimeters. This work provides a detailed discussion of the results obtained by probing a PWO (lead tungstate) oriented sample with $120~mathrm{GeV}/c$ electrons and positrons at the CERN North Area: in particular, a comparison between the outcomes obtained with electrons and positrons is made. Moreover, output radiation measurements on a thinner oriented PWO sample have been recently performed in the sub-GeV regime at the MAMI-B facility: an overview on the resulting characterisation is given