210 research outputs found
The Dorcatoma Herbst, 1792 (Coleoptera: Anobiidae) species of Estonia
The collection specimens of the genus Dorcatoma Herbst, 1792 were revised for Estonia. A substantial part of the material was reared from fruiting bodies of bracket fungi. Seven species of the genus are found in the country. Five of them, D. flavicornis F., D. substriata Hummel, D. punctulata Mulsnat & Rey, D. robusta Strand and D. lomnickii Rtt. are new for Estonia, the last also being new for the Northern Europe and Eastern Baltic regions. Data on the ecology and distribution of the species in Estonia are presented. Comments are given on the systematics and geographical distribution of D. lomnickii and D. obtrita Logv
ГАЛИЧ НА АКВАРЕЛЯХ НАПОЛЕОНА ОРДИ
The article describes the water colours of Napoleon Orda with the images of Halych created in 1878/1880. It is emphasized that until now only one lithography based on the drawing of Napoleon Orda has been known in historical science, depicting the center of Halych and Mount Zamkova from the left bank of the Dnister river. The publication describes two other little/known drawings of the author with the images of the Market Square and ruins of the castle, and the St. Panteleimon church. Both drawings, made with pencil and glue colours in watercolor technique, were preserved in the funds of the National Museum of Krakow in very good condition, they are published for the first time.У статті описано акварелі Наполеона Орди із зображеннями Галича, створені в 1878–1880 роках. Підкреслено, що досі в історичній науці була відома тільки одна, виконана на основі рисунка Н. Орди літографія із зображенням середмістя Галича та Замкової гори з лівого берега Дністра. В публікації описано два інші, маловідомі, рисунки автора із зображеннями Ринкової площі й руїн замку, а також церкви Святого Пантелеймона. Обидва рисунки, виконані олівцем і клеєвими фарбами технікою акварелі, збереглися у фондах Національного музею Кракова в дуже доброму стані, вони публікуються вперше
Low-temperature creation of Frenkel defects via hot electron-hole recombination in highly pure NaCl single crystals
The creation spectrum of stable F centres (being part of F-H pairs of Frenkel defects) by synchrotron radiation of 7–40 eV has been measured for highly pure NaCl single crystals at 12 K using a highly sensitive luminescent method. It is shown that the efficiency of F centre creation in a closely packed NaCl is low at the decay of anion or cation excitons (7.8–8.4 and 33.4 eV, respectively) or at the recombination of relaxed conduction electrons and valence holes. Only the recombination of nonrelaxed (hot) electrons with holes provides the energy exceeding threshold value EFD, which is sufficient for the creation of Frenkel defects at low temperature
Progress in development of a new luminescence setup at the FinEstBeAMS beamline of the MAX IV laboratory
The main funding for the FinEstBeAMS beamline has been obtained from the European Union through the European Regional Development Fund (project “Estonian beamline to MAX-IV synchrotron”, granted to the University of Tartu) and from the Academy of Finland through the Finnish Research Infrastructure funding projects ( FIRI2010 , FIRI2013 , FIRI2014 ). The authors also acknowledge the funding contributions of the University of Oulu , University of Turku , Tampere University of Technology , the Estonian Research Council ( IUT 2-25 , IUT 2-26 , PRG-111 ), as well as the Estonian Centre of Excellence in Research “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics” TK141 (2014-2020.4.01.15-0011). The strategic funding of Finnish FIMAX consortium coordinating university , University of Oulu , for beamline personnel is also acknowledged. The authors thank the MAX IV Laboratory for financial and infrastructural support as well as for assistance during the construction of the FinEstBeaMS beamline.FinEstBeAMS is a new materials science beamline at the 1.5 GeV storage ring of the MAX IV Laboratory in Lund, Sweden. It has been built based on grazing incidence monochromatization of synchrotron light, which allows to cover a remarkably wide excitation energy range from ultraviolet to soft x-rays (4.5–1450 eV). A new mobile luminescence spectroscopy end station has been commissioned with design benefitting from the advantages of a high flux elliptically polarizing undulator light source. We report on the design of the luminescence end station, its technical realization and performance achieved so far. Special attention is paid to the experimental challenges for luminescence spectroscopy under grazing incidence excitation conditions. The first luminescence results obtained demonstrate a reliable performance of the advanced setup at FinEstBeAMS.Eesti Teadusagentuur IUT 2-25,PRG-111,IUT 2-26; European Commission; University of Tartu; Academy of Finland FIRI2010,FIRI2013,FIRI2014; Tampereen Teknillinen Yliopisto; Turun Yliopisto; European Regional Development Fund;
Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART
Ultrafast hybrid nanocomposite scintillators: A review
In recent years, demand for scintillation detectors with high time resolution (better than 100 ps) has emerged in high-energy physics and medical imaging applications. In particular, time of flight positron emission tomography (TOF-PET) can greatly benefit from increasing time resolution of scintillators, which leads to the increase of signal-to-noise ratio, decrease of patient dose, and achievement of the superior spatial resolution of PET images. Currently, extensive research of various types of materials is carried out to achieve the best time resolution. In this review, the recent progress of various approaches is summarized and scintillation compounds with the best temporal characteristics are first reviewed. The review presents the physical processes causing fast luminescence in inorganic and organic materials. Special attention is paid to nanocomposites which belong to a new perspective class of scintillating materials, consisting of a plastic matrix, inorganic nanocrystalline fillers, and organic or inorganic luminescence activators and shifters. The main features and functions of all parts of existing and prospective nanocomposite scintillators are also discussed. A number of currently created and investigated nanocomposite materials with various compounds and structures are reviewed. © 2021 Elsevier B.V.Eesti Teadusagentuur, ETAg: PRG111, PRG629; European Regional Development Fund, ERDF: 2014-2020.4.01.15–0011, TK141Authors thank Minobrnauki project FEUZ-2020-0059 and Estonian Research Council (grants PRG629 and PRG111 ) for financial support. Authors are also grateful for partial support from the European Regional Development Fund (DoRA Pluss program) and the ERDF funding in Estonia granted to the Center of Excellence TK141 “ Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics ” (project No. 2014-2020.4.01.15–0011 )
Lattice Distortions Around a Tl+ Impurity in NaI:Tl+ and CsI:Tl+ Scintillators. An Ab Initio Study Involving Large Active Clusters
Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity
centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of
increasing complexity and show that the lattice relaxation around the Tl+
impurity implies the concerted movement of several shells of neighbors. The
results also reveal the importance of considering a set of ions that can
respond to the geometrical displacements of the inner shells by adapting
selfconsistently their wave functions. Comparison with other calculations
involving comparatively small active clusters serves to assert the significance
of our conclusions. Contact with experiment is made by calculating absorption
energies. These are in excellent agreement with the experimental data for the
most realistic active clusters considered.Comment: 7 pages plus 6 postscript figures, LaTeX. Submmited to Phys, Rev.
Validation of the model of TSL isothermal decay in dosimetric α-Al 2 O 3 crystals
New features of isothermal build-up of thermally stimulated luminescence (TSL) related to deep traps in anion-deficient alumina single crystals are revealed. It was found that the TSL build-up at 630–750 K depends on the structure of the glow curve and is associated with the presence of a high-temperature component with T m = 700 K. Isothermal TSL build-up for the peak at 573 K is well expressed in UV-irradiated samples and is very weak after sample irradiation by a pulsed electron beam. The TSL build-up for this peak is registered for the luminescence of F centres but is absent for the emission of F 2 2+ centres and chromium ions. The obtained results confirm the validity of the kinetic model of the TSL build-up that takes into account the process of thermal ionization of the excited states of F centres in aluminum oxide. © 2019 Elsevier LtdEesti Teadusagentuur: IUT2-26, PUT PRG111Russian Science Foundation, RSF: 18-72-10082This work was financially supported by the Russian Science Foundation , project No. 18-72-10082 and Estonian Research Council , projects IUT2-26 and PUT PRG111
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