Time Reversal Invariance Violating and Parity Conserving effects in Neutron Deuteron Scattering

Time reversal invariance violating parity conserving effects for low energy elastic neutron deuteron scattering are calculated for meson exchange and EFT-type of potentials in a Distorted Wave Born Approximation, using realistic hadronic wave functions, obtained by solving three-body Faddeev equations in configuration space.Comment: There was a technical mistake in calculations due to singular behavior of Yukawa functions at short range. We corrected the integration algorithm. There were some typos which are corrected. arXiv admin note: text overlap with arXiv:1104.305

Oscillations of the superconducting critical current in Nb-Cu-Ni-Cu-Nb junctions

We report on experimental studies of superconductor-ferromagnet layered structures. Strong oscillations of the critical supercurrent were observed with the thickness variation of the ferromagnet. Using known microscopic parameters of Ni, we found reasonable agreement between the period of oscillations and the decay of the measured critical current, and theoretical calculations.Comment: 5 page

Sub-lattice of Jahn-Teller centers in hexaferrite crystal

A novel type of sub-lattice of the Jahn-Teller (JT) centers was arranged in Ti-doped barium hexaferrite BaFe12O19. In the un-doped crystal all iron ions, sitting in five different crystallographic positions, are Fe3+ in the high-spin configuration (S = 5/2) and have a non-degenerate ground state. We show that the electron-donor Ti substitution converts the ions to Fe2+ predominantly in tetrahedral coordination, resulting in doubly-degenerate states subject to the E⊗ e problem of the JT effect. The arranged JT complexes, Fe2+O4, their adiabatic potential energy, non-linear and quantum dynamics, have been studied by means of ultrasound and terahertz-infrared spectroscopies. The JT complexes are sensitive to external stress and applied magnetic field. For that reason, the properties of the doped crystal can be controlled by the amount and state of the JT complexes. © 2020, The Author(s).Deutscher Akademischer Austauschdienst, DAADRussian Foundation for Basic Research, RFBR: 18–02–00332 aDeutscher Akademischer Austauschdienst, DAAD: 91728513Ministry of Education and Science of the Russian Federation, Minobrnauka: 19–53–0401019–72–00055Ministry of Education and Science of the Russian Federation, MinobrnaukaThe authors acknowledge fruitful discussions with A.S. Prokhorov. We acknowledge support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL). At Ural Federal University, the research was supported by the Russian Foundation for Basic Research (18–02–00332 a), UrFU Center of Excellence “Radiation and Nuclear Technologies” (Competitiveness Enhancement Program), the Ministry of Education and Science of the Russian Federation (Program 5–100). In M.N. Miheev Institute of Metal Physics, the research was carried out within the state assignment of the Ministry of Education and Science of the Russian Federation (theme “Electron” No. AAAA-A18–118020190098–5. At South Ural State University, the authors were generally supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0011. The single crystal growth part was supported by Russian Foundation for Basic Research (19–53–04010). At Moscow Institute of Physics and Technology, the work was supported by the Russian Ministry of Education and Science (Program 5–100) and by the German Academic Exchange Service (DAAD) Michael Lomonosov Programm Linie B, 91728513. Time-domain low temperature spectroscopic experiments were financially supported by the Russian Scientific Foundation (19–72–00055)

The Nab Experiment: A Precision Measurement of Unpolarized Neutron Beta Decay

Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, $\lambda = g_A / g_V$, through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter $a$ with a precision of $\delta a / a = 10^{-3}$ and the Fierz interference term $b$ to $\delta b = 3\times10^{-3}$ in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio $\lambda$ with a precision of $\delta \lambda / \lambda = 0.03\%$ that will allow an evaluation of $V_{ud}$ and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.Comment: Presented at PPNS201

Josephson effect in double-barrier superconductor-ferromagnet junctions

We study the Josephson effect in ballistic double-barrier SIFIS planar junctions, consisting of bulk superconductors (S), a clean metallic ferromagnet (F), and insulating interfaces (I). We solve the scattering problem based on the Bogoliubov--de Gennes equations and derive a general expression for the dc Josephson current, valid for arbitrary interfacial transparency and Fermi wave vectors mismatch (FWVM). We consider the coherent regime in which quasiparticle transmission resonances contribute significantly to the Andreev process. The Josephson current is calculated for various parameters of the junction, and the influence of both interfacial transparency and FWVM is analyzed. For thin layers of strong ferromagnet and finite interfacial transparency, we find that coherent (geometrical) oscillations of the maximum Josephson current are superimposed on the oscillations related to the crossover between 0 and $\pi$ states. For the same case we find that the temperature-induced $0-\pi$ transition occurs if the junction is very close to the crossovers at zero temperature.Comment: 13 pages, 6 figure

Анализ возможности применения топологической оптимизации при проектировании зубчатых передач

The paper conducts a feasibility analysis for using a topology optimization (TO) when designing the gears for advanced engines.The goal of TO is to find an optimal material distribution in designing area for given loads with constraints consideration. This study performs 3D computations using a finite-element analysis.Optimization of the certain statements of the problem has been provided. In case 1 an increasing rigidity of diaphragm of the helical gear with decreasing mass was specified, as a criterion. As a result of optimization there were two conical sections getting into one thin wall, connected at the face where the axial force is applied. Some aviation engine and helicopter transmission schemes have a similar embodiment of a diaphragm of the helical gear. In case 2 the frequency detuning was carried out. The result is a complicated design, containing closed cavities, so it is hard to manufacture it by traditional manufacturing methods. Case 3 solves a problem of increasing torsional rigidity with mass restrictions. The optimized design has a splitting diaphragm and a closed cavity.The final calculation is carried out for case 1. As a result, maximum displacements for initial and optimized designs are obtained. The analysis and comparing results have shown that the optimized design has over 2 times increased diaphragm rigidity as compared to the initial design, with mass being 10 % less and equivalent stresses reduced by 13%.The analysis of the results has shown that TO can be used in designing gears taking into account the requirements for mass, rigidity, natural frequencies. It is advisable to refine a design of components using parametric optimization after TO and engineering study of results.Выполнен анализ возможности применения топологической оптимизации (ТО) при проектировании зубчатых передач перспективных двигателей.Целью ТО является определение оптимального распределения материала в области проектирования при заданных нагрузках с удовлетворением критериев и ограничений оптимизации. В данной работе расчёты проводились в 3D постановке с применением метода конечных элементов.Проведена оптимизация нескольких шестерен в различных постановках. Для расчётного случая №1 в качестве критерия задавалось повышение жесткости диафрагмы косозубого зубчатого колеса при снижении массы. Результат оптимизации и последующей конструктивной проработки представляет собой два конусных участка, переходящие в одну тонкую стенку, соединенную с зубчатым венцом у торца, со стороны которого действует осевая сила. Похожее конструктивное исполнение диафрагмы косозубого колеса встречается в некоторых схемах авиационных двигателей и вертолетных трансмиссий. Для расчётного случая №2 проводилась отстройка собственных частот колебаний от возможных резонансов в рабочем диапазоне частот. В результате получена сложная конструкция, имеющая внутренние замкнутые полости, что сильно затрудняет изготовление с применением традиционных методов. Для случая №3 решалась задача повышения крутильной жесткости прямозубой цилиндрической шестерни для сопротивления потере устойчивости с учетом ограничений по массе. Оптимизированная конструкция имеет разветвление диафрагмы у венца и внутреннюю замкнутую полость.Поверочный расчет проведен для постановки №1, в результате которого для исходного и оптимизированного вариантов шестерен получены максимальные перемещения. Анализ и сравнение результатов показали, что жесткость венца в осевом направлении повышена более чем в два раза в сравнении с исходной конструкцией при выигрыше в массе в 10% и снижении максимальных эквивалентных напряжений на 13%.Анализ полученных результатов показал возможность применения ТО при проектировании зубчатых передач с учётом требований по массе, жесткости, собственным частотам колебаний. Рекомендуется уточнять конструктивный облик деталей с помощью параметрической оптимизации после проведения ТО и проработки результатов

Dual targeting of the epigenome via FACT complex and histone deacetylase is a potent treatment strategy for DIPG

Diffuse intrinsic pontine glioma (DIPG) is an aggressive and incurable childhood brain tumor for which new treatments are needed. CBL0137 is an anti-cancer compound developed from quinacrine that targets facilitates chromatin transcription (FACT), a chromatin remodeling complex involved in transcription, replication, and DNA repair. We show that CBL0137 displays profound cytotoxic activity against a panel of patient-derived DIPG cultures by restoring tumor suppressor TP53 and Rb activity. Moreover, in an orthotopic model of DIPG, treatment with CBL0137 significantly extends animal survival. The FACT subunit SPT16 is found to directly interact with H3.3K27M, and treatment with CBL0137 restores both histone H3 acetylation and trimethylation. Combined treatment of CBL0137 with the histone deacetylase inhibitor panobinostat leads to inhibition of the Rb/E2F1 pathway and induction of apoptosis. The combination of CBL0137 and panobinostat significantly prolongs the survival of mice bearing DIPG orthografts, suggesting a potential treatment strategy for DIPG

Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation

The current status of electric dipole moments of diamagnetic atoms which involves the synergy between atomic experiments and three different theoretical areas -- particle, nuclear and atomic is reviewed. Various models of particle physics that predict CP violation, which is necessary for the existence of such electric dipole moments, are presented. These include the standard model of particle physics and various extensions of it. Effective hadron level combined charge conjugation (C) and parity (P) symmetry violating interactions are derived taking into consideration different ways in which a nucleon interacts with other nucleons as well as with electrons. Nuclear structure calculations of the CP-odd nuclear Schiff moment are discussed using the shell model and other theoretical approaches. Results of the calculations of atomic electric dipole moments due to the interaction of the nuclear Schiff moment with the electrons and the P and time-reversal (T) symmetry violating tensor-pseudotensor electron-nucleus are elucidated using different relativistic many-body theories. The principles of the measurement of the electric dipole moments of diamagnetic atoms are outlined. Upper limits for the nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained combining the results of atomic experiments and relativistic many-body theories. The coefficients for the different sources of CP violation have been estimated at the elementary particle level for all the diamagnetic atoms of current experimental interest and their implications for physics beyond the standard model is discussed. Possible improvements of the current results of the measurements as well as quantum chromodynamics, nuclear and atomic calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for EPJ