Upconversion assisted self-pulsing in a high-concentration erbium doped fiber laser

We report results on experimental and theoretical characterisation of self-pulsing in high concentration erbium doped fibre laser which is free from erbium clusters. Unlike previous models of self-pulsing accounting for pair-induced quenching (PIQ) on the clustered erbium ions, new model has been developed with accounting for statistical nature of the excitation migration and upconversion and resonance-like pumpto-signal intensity noise transfer. The obtained results are in a good agreement with the experimental data

АПРИОРНАЯ ОЦЕНКА МЕТРОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК РЕНТГЕНОФЛУОРЕСЦЕНТНЫХ ОПРЕДЕЛЕНИЙ СОДЕРЖАНИЯ ЭЛЕМЕНТОВ И СНИЖЕНИЯ ВЕЛИЧИНЫ МЕЖЭЛЕМЕНТНЫХ ВЛИЯНИЙ ПРИ РАЗБАВЛЕНИИ ПРОБ

A method for a priori estimation of improving the metrological characteristics of X-ray fluorescent definitions of the elements’ content and reducing the inter-elemental influences when diluting the analyzed samples by "heavy" or "light" diluents was demonstrated. The metrological characteristics were evaluated by modeling the measurement process on the scanning X-ray spectrometer using experimentally measured analytical characteristics of the spectrometer. The calculations were performed for the following models: molybdenum with the content of 1 to 80% mas. in light, neutral and heavy fillers, iron in iron ore concentrate at different degrees of dilution with lithium tetra borate and chromium oxide and uranium in corium material at different degrees of dilution with lithium tetra borate and zinc oxide. For the calculations, a method that allowed a priori estimation of the metrological characteristics of quantitative X-ray fluorescence analysis was used. The following metrological characteristics were evaluated: statistical limit of C0 detection using the 3σ criterion, differential sensitivity (η-speed estimates of the analytical line for the percentage of changes in the content of the element) and the average quadratic deviation of the measuring the σC element result content through the basic analytical parameters of the X-ray spectrometer such as integral sensitivity (I0 - experimental analysis line count speed on a single-cell sample), contrast (K-ratio of integral sensitivity to the background score speed), limit of basic hardware error A0 and theoretical coefficients (P-absorption factors) for the material under the known conditions of fluorescence excitation and measurement conditions (T-exposure). It was demonstrated that in the case of small degree of samples dilution with the heavy diluent, the effect of improving the metrological characteristics of X-ray fluorescent content definition was achieved. The same effect was achieved with more dilution by the light diluent. The proposed method of analysis could be used in planning methodical works for the selection of the degree of dilution in the analysis of solvents and powder materials.Keywords: X-ray fluorescent analysis, metrological characteristics, analytical parameters, light diluted, heavy dilutedDOI: http://dx.doi.org/10.15826/analitika.2020.24.1.006  B.D. Kalinin1, S.K. Saveliev2, J.I. Sergeyev3 1“Pretsizion Tekhnologies” Co. Lt, ul. Altai, 12, St. Petersburg, 196066, Russian Federation2Baltic State Technical University, ul.1st Krasnoarmeyskaya, 1, St. Petersburg, 195001, Russian Federation3“Spectron”, NPO LTD, ul. Tsiolkovsky, 10a, St. Petersburg, 190103, Russian FederationПредлагается способ априорной оценки улучшения метрологических характеристик рентгенофлуоресцентных определений содержания элементов и снижения межэлементных влияний при разбавлении анализируемых проб «тяжелым» или «легким» разбавителем. Метрологические характеристики оценивали путем моделирования процесса измерений на сканирующем рентгеновском спектрометре с использованием экспериментально измеренных аналитических характеристик спектрометра. Расчет метрологических характеристик был проведен для моделей: молибден при содержаниях от 1 до 80 % мас. в легком, нейтральном и тяжелом наполнителях, железо в железорудном концентрате при разных кратностях разбавления тетраработатом лития и оксидом хрома и уран в кориумном материале при разных кратностях разбавления тетраборатом лития и оксидом цинка. Для расчета был использован способ, позволяющий априорно оценивать метрологические характеристики количественного рентгенофлуоресцентного анализа: статистический предел обнаружения C0 по критерию 3s, дифференциальную чувствительность (h-скорость счета аналитической линии на процент изменения содержания элемента) и среднее квадратическое отклонение результата измерения содержания элемента sС через основные аналитические параметры рентгеновского спектрометра: интегральную чувствительность (I0 – экспериментальная скорость счета аналитической линии на одноэлементном образце), контрастность (K – отношение интегральной чувствительности к скорости счета фона), предел основной аппаратурной погрешности A0 и теоретические коэффициенты (P – абсорбционные факторы) для исследуемого материала при известных условиях возбуждения флуоресценции и условиях измерения (Т – экспозиция). В результате проведенных исследований показано, что при разбавлении проб тяжелым разбавителем при сравнительно небольшой кратности разбавления достигается эффект улучшения метрологических характеристик рентгенофлуоресцентного определения содержаний элементов и снижения величины межэлементных влияний такой же, как и при большей кратности разбавления легким разбавителем. Предлагаемый способ оценки может быть применен при планировании методических работ для выбора разбавителя и кратности разбавления при анализе растворов и порошковых материалов.Ключевые слова: рентгенофлуоресцентный анализ, метрологические характеристики, аналитические параметры, легкий разбавитель, тяжелый разбавительDOI: http://dx.doi.org/10.15826/analitika.2020.24.1.00

A π-Extended Donor-Acceptor-Donor Triphenylene Twin linked via a Pyrazine-bridge

Beta-amino triphenylenes can be accessed via palladium catalyzed amination of the corresponding triflate using benzophe-none imine. Transformation of amine 6 to benzoyl amide 18 is also straightforward and its wide mesophase range demon-strates that the new linkage supports columnar liquid crystal formation. Amine 6 also undergoes clean aerobic oxidation to give a new twinned structure linked through an electron-poor pyrazine ring. The new discotic liquid crystal motif contains donor and acceptor fragments, and is more oval in shape rather than disk-like. It forms a wide range columnar mesophase. Absorption spectra are strong and broad; emission is also broad and occurs with a Stokes shift of ca. 0.7 eV, indicative of charge-transfer characte

The CRESST Dark Matter Search

The current status of CRESST (Cryogenic Rare Event Search using Superconducting Thermometers) and new results concerning the detector development are presented. The basic technique of CRESST is to search for particle Dark Matter (WIMPS, Weakly Interacting Massive particles) by the measurement of non-thermal phonons as created by WIMP-induced nuclear recoils. Combined with the newly developed method of simultaneous measurement of scintillation light, strong background discrimination is possible, resulting in a substantial increase in WIMP detection sensitivity. The short and long term perspectives of CRESST are discussed.Comment: 12 pages, 6 figure

The CRESST Experiment: Recent Results and Prospects

The CRESST experiment seeks hypothetical WIMP particles that could account for the bulk of dark matter in the Universe. The detectors are cryogenic calorimeters in which WIMPs would scatter elastically on nuclei, releasing phonons. The first phase of the experiment has successfully deployed several 262 g sapphire devices in the Gran Sasso underground laboratories. A main source of background has been identified as microscopic mechanical fracturing of the crystals, and has been eliminated, improving the background rate by up to three orders of magnitude at low energies, leaving a rate close to one count per day per kg and per keV above 10 keV recoil energy. This background now appears to be dominated by radioactivity, and future CRESST scintillating calorimeters which simultaneously measure light and phonons will allow rejection of a great part of it.Comment: To appear in the proceedings of the CAPP2000 Conference, Verbier, Switzerland, July, 2000 (eds J. Garcia-Bellido, R. Durrer, and M. Shaposhnikov

A priori assessment of the metrological characteristics of X-ray fl uorescent defi nitions of the elements’ content and the reduction of the inter-elemental infl uences magnitude when diluting the samples

Предлагается способ априорной оценки улучшения метрологических характеристик рентгенофлуоресцентных определений содержания элементов и снижения межэлементных влияний при разбавлении анализируемых проб «тяжелым» или «легким» разбавителем. Метрологические характеристики оценивали путем моделирования процесса измерений на сканирующем рентгеновском спектрометре с использованием экспериментально измеренных аналитических характеристик спектрометра. Расчет метрологических характеристик был проведен для моделей: молибден при содержаниях от 1 до 80 % мас. в легком, нейтральном и тяжелом наполнителях, железо в железорудном концентрате при разных кратностях разбавления тетраработатом лития и оксидом хрома и уран в кориумном материале при разных кратностях разбавления тетраборатом лития и оксидом цинка. Для расчета был использован способ, позволяющий априорно оценивать метрологические характеристики количественного рентгенофлуоресцентного анализа: статистический предел обнаружения C0 по критерию 3s, дифференциальную чувствительность (h-скорость счета аналитической линии на процент изменения содержания элемента) и среднее квадратическое отклонение результата измерения содержания элемента sС через основные аналитические параметры рентгеновского спектрометра: интегральную чувствительность (I0 – экспериментальная скорость счета аналитической линии на одноэлементном образце), контрастность (K – отношение интегральной чувствительности к скорости счета фона), предел основной аппаратурной погрешности A0 и теоретические коэффициенты (P – абсорбционные факторы) для исследуемого материала при известных условиях возбуждения флуоресценции и условиях измерения (Т – экспозиция). В результате проведенных исследований показано, что при разбавлении проб тяжелым разбавителем при сравнительно небольшой кратности разбавления достигается эффект улучшения метрологических характеристик рентгенофлуоресцентного определения содержаний элементов и снижения величины межэлементных влияний такой же, как и при большей кратности разбавления легким разбавителем. Предлагаемый способ оценки может быть применен при планировании методических работ для выбора разбавителя и кратности разбавления при анализе растворов и порошковых материалов.A method for a priori estimation of improving the metrological characteristics of X-ray fluorescent definitions of the elements’ content and reducing the inter-elemental influences when diluting the analyzed samples by "heavy" or "light" diluents was demonstrated. The metrological characteristics were evaluated by modeling the measurement process on the scanning X-ray spectrometer using experimentally measured analytical characteristics of the spectrometer. The calculations were performed for the following models: molybdenum with the content of 1 to 80% mas. in light, neutral and heavy fillers, iron in iron ore concentrate at different degrees of dilution with lithium tetra borate and chromium oxide and uranium in corium material at different degrees of dilution with lithium tetra borate and zinc oxide. For the calculations, a method that allowed a priori estimation of the metrological characteristics of quantitative X-ray fluorescence analysis was used. The following metrological characteristics were evaluated: statistical limit of C0 detection using the 3σ criterion, differential sensitivity (η-speed estimates of the analytical line for the percentage of changes in the content of the element) and the average quadratic deviation of the measuring the σC element result content through the basic analytical parameters of the X-ray spectrometer such as integral sensitivity (I0 - experimental analysis line count speed on a single-cell sample), contrast (K-ratio of integral sensitivity to the background score speed), limit of basic hardware error A0 and theoretical coefficients (P-absorption factors) for the material under the known conditions of fluorescence excitation and measurement conditions (T-exposure). It was demonstrated that in the case of small degree of samples dilution with the heavy diluent, the effect of improving the metrological characteristics of X-ray fluorescent content definition was achieved. The same effect was achieved with more dilution by the light diluent. The proposed method of analysis could be used in planning methodical works for the selection of the degree of dilution in the analysis of solvents and powder materials

Spectroscopic confirmation and modelling of two lensed quadruple quasars in the Dark Energy Survey public footprint

Quadruply lensed quasars are extremely rare objects, but incredibly powerful cosmological tools. Only few dozen are known in the whole sky. Here we present the spectroscopic confirmation of two new quadruplets WG0214-2105 and WG2100-4452 discovered by Agnello & Spiniello (2018) within the Dark Energy Survey public footprints. We have conducted spectroscopic follow-up of these systems with the Southern African Large Telescope as part of a program that aims at confirming the largest possible number of strong gravitational lenses in the equatorial and southern hemisphere. For both systems, we present the sources spectra that allowed us to estimate their redshifts and unambiguously confirm their lensing nature. For the brighter deflector (WG2100-4452) we measure the spectroscopic redshift and the stellar velocity dispersion from optical absorption lines in the spectrum. For the other system we infer the lens redshift from photometry, being the quality of the spectra not good enough. We obtain photometry for both lenses, directly from multi-band images, isolating the lenses from the quasars. One of the quadruplets, WG0214-2105, was also observed by Pan-STARRS, allowing us to estimate the apparent brightness of each quasar image at two different epochs, and thus to find evidence for flux variability. This result could suggest a microlensing event for the faintest components, although intrinsic variability cannot be excluded with only two epochs. Finally, we present simple lens models for both quadruplets, obtaining Einstein radii, SIE velocity dispersions, ellipticities, and position angles of the lenses, as well as time delay predictions assuming a concordance cosmological model

The astrometric Gaia-FUN-SSO observation campaign of 99 942 Apophis

Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO . The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center. We obtained 2103 previously unpublished astrometric positions and provide these to the scientific community. Using these data we show that our reduction of this astrometric campaign with a reliable stellar catalog substantially improves the quality of the astrometric results. We present evidence that the new data will help to reduce the orbit uncertainty of Apophis during its close approach in 2029. We show that uncertainties due to geolocations of observing stations, as well as rounding of astrometric data can introduce an unnecessary degradation in the quality of the resulting astrometric positions. Finally, we discuss the impact of our campaign reduction on the recovery process of newly discovered asteroids.Comment: Accepted for publication in A&