Impedance spectroscopy of synthetic proustite at high pressures

The effect of high pressure (up to 40 GPa) and alternating electric field frequency (100 Hz-500 kHz) on the electrical properties of synthesized single-crystal proustite Ag3AsS3 is studied. The behavior of real and imaginary parts of impedance upon an increase in pressure confirms earlier data on the closing of valence and conduction zones, and on the material's transition to the metal state at ∼30 GPa. © 2013 Allerton Press, Inc

Colossal variations in the thermopower and n-p conductivity switching in topological tellurides under pressure

Under applied high pressure, the electronic, optical, structural, and other properties of narrow-bandgap telluride semiconductors are subjected to dramatic changes. They can include, for instance, structural and electronic topological transitions. In this work, we investigated the electronic properties of single crystals of three families of tellurides, namely, HgTe, PbTe, and Bi2Te3 by measurements of the thermoelectric power (the Seebeck coefficient) and electrical resistance under high pressure up to 10 GPa. The applied pressure led to spectacular variations in the electronic transport of all three tellurides. We addressed these effects to electronic topological transitions that could be driven by significant narrowing of the bandgaps in the normal-pressure phases of these compounds. In particular, at about 1 GPa, we observed an n-p switching in the conductivity of HgTe, which was well reproducible under multiple pressure cycling. In contrast, in PbTe, we found that an electronic topological transition irreversibly turns the conductivity from p- to n-type. An electronic topological Lifshitz transition in p-type Bi2Te3 crystals with a low carrier concentration enhanced the n-type conductivity in a narrow pressure region about 2-3 GPa and resulted in a double p-n-p conductivity inversion. An irreversible p-n conductivity switching in p-type Bi2Te3 happened already on decompression from a high-pressure phase from about 8 GPa. The stress-controlled p-n inversions of the electrical conductivity in these industrially important telluride materials can potentially find emergent applications in micro- and nanoelectronics. © 2020 Author(s).The research was supported by a grant of Ministry of Science and Higher Education of the Russian Federation No. 075-15-2020-797 (13.1902.21.0024)

ИНТЕГРАЛЬНЫЙ МЕТОД ПОСТРОЕНИЯ МАТЕМАТИЧЕСКОЙ МОДЕЛИ И АЛГОРИТМА ИССЛЕДОВАНИЯ ВЯЗКОУПРУГИХ ДЕФОРМАЦИЙ ГРУНТОВЫХ ОСНОВАНИЙ

On the basis of the Boltzmann L. – Volterra V. hereditary creep theory a mathematical model, an algorithm and software for numerical investigation of viscous-elastic deformation of the non-uniform soil base have been developed. The algorithm for investigations of mathematical model is synthesized on the basis of a final element method that allows to take into account heterogeneity of a disperse body.На основе теории наследственной ползучести Больцмана – Вольтерра разработаны математическая модель, алгоритм и программное обеспечение для численного исследования вязкоупругого деформирования неоднородного грунтового основания. Алгоритм исследования математической модели разработан на основе метода конечных элементов, что позволяет учесть неоднородность дисперсного тела

Компьютерное моделирование перенапряжений в распределительных сетях 6–10 кВ при однофазных замыканиях на землю

Nowadays, when designing and operating electric power systems, special attention is paid to predicting emergency situations and minimizing losses in case they occur. The most common method of overvoltage investigations is the use of simulation models in specialized application packages, which imposes additional qualification requirements on the electrical engineer.The authors propose modeling technologies and a software tool for modeling and research of overvoltages that occur in 6–10 kV distribution networks at single-phase ground faults, including the method of visual design of the distribution network through the use of information technology and automated generation of mathematical model for its further study to analyze overvoltages.В настоящее время при проектировании и эксплуатации электроэнергетических систем особое внимание уделяется прогнозирования возникновения аварийных ситуаций и минимизации потерь в случае их появления. Наиболее распространёнными методом исследования перенапряжений являются применение имитационных моделей в специализированных прикладных пакетах, что накладывает дополнительные квалификационные требования на энергетика-проектировщика.Авторами предлагается технологии моделирования и программное средство для моделирования и исследования перенпряжений, возникающих в распределительных сетях 6–10 кВ при однофазных замыканиях на землю, включающее методику визуального проектирования распределительной сети посредством применения информационных технологий и автоматизированную генерацию математической модели для её дальнейшее исследование с целью анализа перенапряжений

KLEVER: An experiment to measure BR(KL→π0ννˉK_L\to\pi^0\nu\bar{\nu}) at the CERN SPS

Precise measurements of the branching ratios for the flavor-changing neutral current decays $K\to\pi\nu\bar{\nu}$ can provide unique constraints on CKM unitarity and, potentially, evidence for new physics. It is important to measure both decay modes, $K^+\to\pi^+\nu\bar{\nu}$ and $K_L\to\pi^0\nu\bar{\nu}$, since different new physics models affect the rates for each channel differently. The goal of the NA62 experiment at the CERN SPS is to measure the BR for the charged channel to within 10%. For the neutral channel, the BR has never been measured. We are designing the KLEVER experiment to measure BR($K_L\to\pi^0\nu\bar{\nu}$) to $\sim$20% using a high-energy neutral beam at the CERN SPS starting in LHC Run 4. The boost from the high-energy beam facilitates the rejection of background channels such as $K_L\to\pi^0\pi^0$ by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from $K_L$ decays escaping through the beam exit amidst an intense background from soft photons and neutrons in the beam. Background from $\Lambda \to n\pi^0$ decays in the beam must also be kept under control. We present findings from our design studies for the beamline and experiment, with an emphasis on the challenges faced and the potential sensitivity for the measurement of BR($K_L\to\pi^0\nu\bar{\nu}$).Comment: 13 pages, 4 figures. Submitted as input to the 2020 update of the European Strategy for Particle Physics. v2: Included authors unintentionally omitted in v