Dependence Of Energy Loss Research Articles

Creation of color centers in MgF2 single crystals by swift heavy ions: Energy loss and fluence dependence

Ion-solid interaction leads to significant modifications in the surface and bulk of different materials. MgF2 of a rutile crystalline structure is an important optical material for a large variety of applications. The single crystals were irradiated with energetic heavy ions of various kinetic energies and fluences. After irradiation, we utilized optical spectroscopy to study the ion-induced defects and their evolutions as a function of ion beam parameters. The absorption spectra show the creation of different types of ion-induced defects, namely F-, F2-, and F3-centers. The concentrations of the observed color centers as well as their creation efficiency are studied in terms of ion energy loss and fluence. The results are of high importance for understanding the degradation of optical materials in space environments.

Quantifying the jet energy loss in Pb+Pb collisions at LHC

In this work, we give a method to study the energy loss of jets in the medium using a variety of jet energy loss observables such as nuclear modification factor and transverse momentum asymmetry in dijets and γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-jets in heavy ion collisions. The energy loss of jets in the medium depends mainly on the size and the properties of medium viz. temperature and is a function of energy of the jets as predicted by various models. A Monte Carlo (MC) method is employed to generate the transverse momentum and path-lengths of the initial jets that undergo energy loss. Using different scenarios of energy loss, the transverse momentum and system size dependence of nuclear modification factors and different measures of dijet momentum imbalance at energies sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s_{\ extrm{NN}}}$$\\end{document} = 2.76 TeV and 5.02 TeV and γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-jet asymmetry at sNN\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s_{\ extrm{NN}}}$$\\end{document} =2.76 TeV in Pb+Pb collisions are simulated. The results are compared with the measurements by ATLAS and CMS experiments as a function of transverse momentum and centrality. The study demonstrates how the system size and energy dependence of jet energy loss can be quantified using various experimental observables.

Взаимосвязь окружной скорости и потерь энергии в проточной части центростремительной турбины с частичным облопачиванием рабочего колеса

Low-consumption turbomachines are devices that play an important role in the drive of various units in the field of shipbuilding, aircraft engineering and other branches of heavy engineering. They have some advantages over a high-average power turbine. The largest number of low-consumption turbomachines are made partial, i.e. with partial intake. The principle of a turbine with partial flapping of the impeller is considered as one of the types of partial turbomachines. The influence of the main velocity characteristic of the turbine stage on the loss of kinetic energy in the stage is investigated. The simulation of gas dynamic processes occurring in the turbine stage was carried out using the ANSYS Workbench software package. With the help of this complex, a three-dimensional geometric model of the turbine stage with varying degrees of impeller damping was created. By applying the finite element method, a computational grid, a computational model are generated, and boundary conditions of a numerical experiment are set. The result of the numerical experiment is graphs of the dependence of kinetic energy loss on the circumferential velocity (speed characteristics of the turbine stage). This dependence can be represented not only graphically, but also with the help of mathematical apparatus. An example of such an apparatus is the polynomial dependence. The considered mathematical design can be used in order to optimize mathematical models of gas flow in the flow part of a low-flow turbine. Cubic two-parameter polynomials of kinetic energy losses in the flow part of the nozzle and impeller are obtained, and an assessment of its applicability in the current mathematical model is given.

Optical Properties of Tlinse2<Au> Single Crystals

This paper presents the results of studying the surface microrelief in 2D and 3D models and analyzing the spectroscopy of a three-junction TlInSe2<Au> crystal. Analysis of the results obtained showed that with a change in the composition of the TlInSe2<Au> crystal, sharp changes occur in the microrelief of its surface. An X-ray optical diffraction analysis of the TlInSe2<Au> crystal was experimentally carried out. Based on ellipsometric data, optical functions were determined - the real and imaginary parts of the dielectric permittivity of crystals, the coefficients of optical absorption and reflection, the dependence of energy losses and electric field power on the effective density, the spectral dependences of the real (σr) and imaginary (σi) parts, optical electrical conductivity were experimentally studied. The fluorescence spectra of the ternary compound TlInSe2<Au> were isolated and analyzed when excited by light with a wavelength of 532 nm. X-ray studies of TlInSe2<Au> showed that this phase crystallizes into tetragonal systems. Ellipsometric measurements showed that the real (ε1) and imaginary (ε2) parts of the dielectric constant are components of the dielectric constant tensor of the uniaxial joints under consideration and do not depend on the angle. Analysis of the dependence of the real and imaginary parts of the refractive index of the TlInSe2<Au> crystal on photon energy showed that the nature of the change in the real and imaginary parts of the dielectric constant does not differ significantly. When analyzing the spectral dependences of the real (σr) and imaginary (σi) parts of the optical electrical conductivity, it was noticed that the real part of the optical electrical conductivity increases exponentially in the energy range 0.894-3.505 eV. In the energy range of 0.654-2.91 eV, the imaginary part of the optical electrical conductivity increases linearly, reaches a maximum value, and decreases at an energy of 2.91 eV. At 3.6 eV, an inversion of the imaginary part of the optical electrical conductivity of the TlInSe2<Au> compound is observed. From the graphs of the effective power density versus electric field energy losses, it is known that the effective power density increases significantly in the energy range of 0.805–3.52 eV. The fluorescence spectrum of the ternary compound TlInSe2<Au> upon excitation with light with a wavelength of 532 nm has been studied and it has been established that this phase has luminescent properties.

Probing the path-length dependence of parton energy loss via scaling properties in heavy ion collisions

The scaling property of large-p⊥ hadron suppression, RAA(p⊥), measured in heavy ion collisions at the relativistic heavy ion collider and at the large hadron collider (LHC) leads to the determination of the average parton energy loss ⟨ε⟩ in quark-gluon plasma produced in a variety of collision systems and centrality classes. Relating ⟨ε⟩ to the particle multiplicity and collision geometry allows for probing the dependence of parton energy loss on the path length L. We find that ⟨ε⟩∝Lβ with β=1.02−0.06+0.09, which is consistent with the perturbative quantum chromodynamics expectation of parton energy loss in a longitudinally expanding quark-gluon plasma. We then demonstrate that the azimuthal anisotropy coefficient divided by the collision eccentricity, v2/e, follows the same scaling property as RAA. This scaling is observed in data, which are reproduced by the model at large p⊥. Finally, a linear relationship between v2/e and the logarithmic derivative of RAA is found and confirmed in data, offering an additional way to probe the L dependence of parton energy loss using coming measurements from LHC run 3. Published by the American Physical Society 2024

Modification of charged-particle jets in event-shape engineered Pb–Pb collisions at [formula omitted] TeV

Charged-particle jet yields have been measured in semicentral Pb–Pb collisions at center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV with the ALICE detector at the LHC. These yields are reported as a function of the jet transverse momentum, and further classified by their angle with respect to the event plane and the event shape, characterized by ellipticity, in an effort to study the path-length dependence of jet quenching. Jets were reconstructed at midrapidity from charged-particle tracks using the anti-kT algorithm with resolution parameters R = 0.2 and 0.4, with event-plane angle and event-shape values determined using information from forward scintillating detectors. The results presented in this letter show that, in semicentral Pb–Pb collisions, there is no significant difference between jet yields in predominantly isotropic and elliptical events. However, out-of-plane jets are observed to be more suppressed than in-plane jets. Further, this relative suppression is greater for low transverse momentum (< 50 GeV/c) R = 0.2 jets produced in elliptical events, with out-of-plane to in-plane jet-yield ratios varying up to 5.2σ between different event-shape classes. These results agree with previous studies indicating that jets experience azimuthally anisotropic suppression when traversing the QGP medium, and can provide additional constraints on the path-length dependence of jet energy loss.

Manipulating fluorine induced bulky dipoles and their strong interaction to achieve high efficiency electric energy storage performance in polymer dielectrics

The pursuit of polymer dielectrics with elevated energy density frequently results in heightened energy loss, thereby hindering practical applications. To decouple the dependence of the high energy loss on the high energy storage performance, based on theoretical simulations, a bulky polar unit constructed from a fluorine atom substituted phenyl ring (4-FSt) is designed and copolymerized with methyl methacrylate (MMA). The fluorine atom is found to induce the dipole formation by deforming π-conjugated electrons distribution on the phenyl ring, which favors reversible polarization behaviors instead of conventional dipole orientation polarization under AC electric field and enhances the energy density of polymers. Meanwhile, the introduction of fluorine atoms possessing electron-withdrawing properties is confirmed to increase the electrons capturing ability and the dipole interactions, which significantly reduces the leakage conduction and orientation relaxation induced energy loss. As a result, the rather high energy discharging efficiency (over 88 %) could be finely maintained up to 825 MV m−1, and a discharge energy density of 16.6 J cm−3 is obtained, which exhibits significant advances over the reported polymer dielectrics. This work presents the first practice to decouple the dependence of high energy storage and energy loss in polymer dielectrics by manipulating the fluorine effect.

Bayesian inference of the path-length dependence of jet energy loss

Bayesian inference of the path-length dependence of jet energy loss

Azimuthal anisotropy of dijet events in PbPb collisions at sqrt{s_{textrm{NN}}} = 5.02 TeV

The path-length dependent parton energy loss within the dense partonic medium created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of sqrt{s_{textrm{NN}}} = 5.02 TeV is studied by determining the azimuthal anisotropies for dijets with high transverse momentum. The data were collected by the CMS experiment in 2018 and correspond to an integrated luminosity of 1.69 nb−1. For events containing back-to-back jets, correlations in relative azimuthal angle and pseudorapidity (η) between jets and hadrons, and between two hadrons, are constructed. The anisotropies are expressed as the Fourier expansion coefficients vn, n = 2–4 of these azimuthal distributions. The dijet vn values are extracted from long-range (1.5 < |∆η| < 2.5) components of these correlations, which suppresses the background contributions from jet fragmentation processes. Positive dijet v2 values are observed which increase from central to more peripheral events, while the v3 and v4 values are consistent with zero within experimental uncertainties.

A first principle investigations for electronic, optical and mechanical response of novel Ba2AgIO6 perovskite

The double perovskite compound, Ba2AgIO6 has been studied through density functional theory to explore its mechanical, electronic, and optical properties. To examine the mechanical stability of the compound, elastic constants, Young’s modulus, bulk modulus and shear modulus have been computed. The computed electronic properties show the direct band gap semiconducting nature of the studied perovskite compound. The optical properties of Ba2AgIO6 are interpreted with the help of energy dependent dielectric tensor, absorption, reflection, refraction, and energy loss spectra. From the present study it is found that Ba2AgIO6 is suitable for the various photovoltaic and optoelectronic applications.

Spectroscopic Investigation of Structural Perturbations in CsPbCl3 Perovskite Nanocrystals: Temperature- and Excitation-Energy-Dependent Study

Inorganic lead halide perovskites are at the frontier of photovoltaic research due to their groundbreaking performance as an absorbing layer in solar cells. Cesium lead chloride (CsPbCl3), known to be a competent material for its blue emission, undergoes subsequent temperature-dependent phase transitions. The photophysical aspects reliant on temperature as well as the phase exhibited by the material are still unknown. Herein, we have studied the temperature- and excitation-energy-dependent underlying photophysics in CsPbCl3 nanocrystals (NCs) employing ultrafast transient absorption (TA) and terahertz (THz) spectroscopy. The direct dependence of carrier relaxation, carrier temperature, and energy loss on the phase transition has been established. Also, to comprehend the outcome of excitation energy, photoconductivity and mobility were determined with the help of optical pump THz probe spectroscopy, and it is established that as the excitation energy is reduced, mobility decay is found to be slow due to diminishing Auger recombination and augmented penetration depth.

Measurement of nonprompt and prompt D0 azimuthal anisotropy in Pb-Pb collisions at √SNN = 5.02 TeV

Heavy quarks are primarily produced via initial hard scatterings, and thus carry information about the early stages of the Quark-Gluon Plasma (QGP). Measurements of the azimuthal anisotropy of the final-state heavy flavor hadrons provide information about the initial collision geometry, its fluctuation, and more importantly, the mass dependence of energy loss in QGP. Due to the larger bottom quark mass as compared to the charm quark mass, separate measurements of charm and bottom hadron azimuthal anisotropy can shed new light on understanding the dependence of the heavy quark and medium interaction. Because of the high branching ratio and large D0 mass, measurements of D0 meson coming from bottom hadron decay (nonprompt D0) can cover a broad kinematic range and be a good proxy of the parent bottom hadrons results. In this talk, we report on the prompt D0 and the first nonprompt D0 measurements of the azimuthal anisotropy elliptic (v2) and triangular (v3) coefficients of nonprompt D0 in PbPb collisions at √SNN = 5.02 TeV. The measurements are performed as functions of transverse momentum pT, in three centrality classes, from central to midcentral collisions. Compared to the prompt D0 results, the nonprompt D0 v2 flow coefficients are systematically lower but have a similar dependence on pT and centrality. A non-zero v3 coefficient of the nonprompt D0 is observed. The obtained results are compared with theoretical predictions. The comparison could provide new constraints on the theoretical description of the interaction between heavy quarks and the medium.

Beauty production in heavy–ion collisions with ALICE at the LHC

In this contribution, the measurement of the centrality dependence of the nuclear modification factor (RAA) of non-prompt D0 meson in Pb-Pb collisions at √SNN = 5.02 TeV is presented. This measurement provides important constraints to the in-medium mass dependence of energy loss and hadroniza-tion of the beauty quark. In addition, the first measurements of non-prompt Ds+ meson production in central and semi-central Pb-Pb collisions at √SNN = 5.02 TeV are discussed. The non-prompt Ds+ meson measurements provide further information on the production and hadronization of Bs0 mesons. Finally, the first measurement of non-prompt D-meson elliptic flow in Pb-Pb collisions at √SNN = 5.02 TeV is shown. This measurement can help to investigate the degree of thermalization of beauty quarks in the hot and dense QCD medium.

Effect of mechanical cutting on the energy loss of laser-scribed grain-oriented alloys

We investigate the effect of mechanical cutting on the magnetic properties of high permeability grain-oriented (HGO) laser-scribed Fe-Si sheets. Measurements have been performed on strips of different widths (5 to 60 mm) cut from 0.27 mm thick sheets. Normal magnetization curve and energy loss have been determined by means of a digitally controlled single strip tester from 1 Hz to 1 kHz at peak magnetic polarization values Jp = 1000 mT and 1700 mT. The results fit into a simple phenomenological model regarding the dependence of magnetization curve and energy loss on the strip width, in substantial continuity with the approach originally developed for non-oriented electrical steels. The hysteresis Wh and excess Wexc loss components are shown to depend on the strip width according to a hyperbolic law, with a limiting fully hardened strip predicted to occur for widths around 3.5 mm. It is then consistently observed that the mechanical cutting of standard 30 mm wide HGO Epstein strips is conducive to an increase of the energy loss at 50 Hz and 1.7 T of the order of 13 %.

Donor End-Capped Alkyl Chain Length Dependent Non-Radiative Energy Loss in All-Small-Molecule Organic Solar Cells.

A critical bottleneck for further efficiency breakthroughs in organic solar cells (OSCs) is to minimize the non-radiative energy loss (eΔVnr ) while maximizing the charge generation. With the development of highly emissive low-bandgap non-fullerene acceptors, the design of high-performance donors becomes critical to enable the blend with the electroluminescence quantum efficiency to approach or surpass the pristine acceptor. Herein, by shortening the end-capped alkyl chains of the small-molecular donors from hexyl (MPhS-C6) to ethyl (MPhS-C2), the material obtained aggregation that wasinsensitive to thermal annealing (TA) along withcondensed packing simultaneously. The former leads to small phase separation and suppressed upshifts of the highest occupied molecular orbital energy level during TA, and the latter facilitates its efficient charge-transport at aggregation-less packing. Hence, the ΔVnr decreases from 0.242 to 0.182V, from MPhS-C6 to MPhS-C2 based OSCs. An excellent PCE of 17.11% is obtained by 1,8-diiodoctane addition due to almost unchanged high Jsc (26.6mA cm-2 ) and Voc (0.888V) with improved fill factor, which is the record efficiency with the smallest energy loss (0.497eV) and ΔVnr (0.192V) in all-small-molecule OSCs. These results emphasize the potential material design direction of obtaining concurrent TA-insensitive aggregation and condensed packing to maximize the device performances with a super low ΔVnr .

Switches of Powerful Nanosecond Current Pulses Based on High-Voltage Units of Shock Ionized Dynistors

Monounit and modular switches of high-power current pulses with an operating voltage of 12 kV, made on the basis of series-connected shock ionized dynistors, are described. The switching processes of these switches are studied. The dependence of switching energy losses on the control pulse power is determined. The possibility of switching nanosecond current pulses with an amplitude of several kiloamperes at a frequency of several hundred hertz is shown.

INFORMATION TECHNOLOGIES FOR STUDYING PARAMETERS FOR SIMULATING COMPLEX SCHEMES OF ELECTRICAL SUPPLY OF ELECTRICAL TRANSPORT TRACTION NETWORKS

The parameters of complex power supply schemes of tram lines, which are required for simulation modeling, were studied: statistical characteristics of traction loads of feeders and voltage on the tires of traction substations. It was established that the distribution function of the feeder feeding the tram depot corresponds to the logarithmic normal law, the distribution function of the modules of the idle voltage deviation and the angles between the idle voltages of adjacent traction substations to the truncated normal law. It is proposed to modernize the information bases of electric traction network parameters with complex power schemes to increase the efficiency of modeling the modes of operation of sections of urban electric transport. A method of calculating instantaneous schemes has been developed, which allows to create algorithms that do not depend on the degree of complexity of the scheme. A method of simulation modeling of complex power supply systems of electric transport based on the synthesis of the matrix method of calculating instantaneous circuits and the method of statistical tests for modeling the organization of traffic of trams and trolleybuses is proposed. Algorithms and simulation models of traction power supply systems of urban electric transport have been developed, taking into account the modes of operation of power systems. A single simulation complex has been created that takes into account the traffic schedules of trams and trolleybuses, power flows in power supply systems, which makes it possible to obtain generalized dependences of power flows and energy losses, and to increase the accuracy of calculations of electrical parameters to 5–7%. Adequacy of the simulation model to the real process was verified by experimental data on a number of two-track, single-track sections of electric traction networks and complex power supply schemes of traction substations. The error in determining the integral indicators of costs and energy losses does not exceed 5%, and the rms currents – 3%. The use of simulation modeling in the design of traction power supply systems allows to improve the quality of electrical engineering calculations of complex power supply schemes and to propose energy-efficient power supply modes.

Определение затрат энергии в синхронных тяговых генераторах тепловозов при различных режимах нагружения

Purpose: To develop a methodology for determining energy consumption in synchronous traction generators depending on implemented workload mode. To calculate traction characteristics of a locomotive it is necessary to obtain analytical dependences of energy losses in a synchronous traction generator from rotation frequency of its shaft, electric current and voltage at rectifier plant. To solve the problem of determining significance of various components of losses in a synchronous traction generator under different operating modes. Methods: Investigation of all components of energy losses in a traction synchronous generator. Conclusion of analytical dependencies that allow calculating all components of losses in generator depending on its design parameters by obtaining constant coefficients that depend on design parameters of generator. Results: The values of capacity spending for energy conversion in a synchronous traction generator are determined. The obtained dependences allow us to perform refined analysis of losses in a traction drive. It is shown that the capacity of mechanical losses at a nominal speed reaches 50 kW, capacity of electrical and magnetic losses can reach 20 kW. Practical importance: The results obtained allow us to clarify the amount of energy consumption in a traction drive of locomotives and improve the accuracy of traction calculations. The nature of the change in losses in a synchronous traction generator depending on speed, voltage and current at the output of rectifier plant and its design parameters is shown. The results can be used, among other things to clarify traction characteristics of locomotives.

The ϕ meson production from small to large systems of ion collisions at and 193 GeV

The measurement of ϕ meson production is a unique tool to explore the characteristics of the quark-gluon plasma. The ϕ meson has a small interaction cross section therefore its yields and elliptic flow are good probes of the quark-gluon plasma properties. The ϕ meson production can be sensitive to the strangeness enhancement effect and can provide information about the flavor dependence of energy loss and elliptic flow. Measurements in different nucleus-nucleus collisions allow us to perform a systematic investigation of the nuclear matter effects, system size and geometry influence on ϕ meson production. The PHENIX experiment has measured transverse momentum spectra, nuclear modification factors R AB , and elliptic anisotropy parameter v 2 for ϕ mesons in p+Al, p/d/3 He/Cu+Au collisions at and in U + U collisions at at midrapidity (∣η∣ < 0.35). The obtained results exhibit scaling of v 2 for ϕ mesons with eccentricity of participant nucleons (collision geometry), whereas the ϕ R AB values depend on the number of binary nucleon-nucleon collisions (system size). The comparison of experimental data on the ϕ meson to various model calculations (AMPT, iEBE-VISHNU and PYTHIA/Angantyr) suggests the importance of viscous hydrodynamics and the coalescence mechanism in describing the properties and hadronization of the QGP.

Power management of variable capacitors in electrical grid systems according to the criterion of mini-mum energy loss

The aim is to manage the transmitted reactive power in electrical grids using variable capacitor batteries according to the criterion of minimum energy loss under different annual reactive load schedules and different numbers of variable capacitor sections. The main theoretical relations were obtained by the methods of mathematical modelling and integral calculus using the theory of optimal control. The influence of the power and number of sections in a capacitor battery on energy losses in the grid was estimated using computational experiments. Dependencies for energy losses in a capacitor battery, as well as for reducing energy losses in the grid, were obtained. These expressions are valid for linearized load schedules. It is shown that the dependences of energy losses in a capacitor battery and the reduction of losses in the grid on the section power have inflection points and pass through a maximum. The presence of inflection points is associated with a change in the number of capacitor sections operating throughout the year. The presence of a maximum is explained by the fact that, with an increase in the power of the capacitor battery, its operating time decreases under the complete number of variable sections. It is established that the batteries of static capacitors with two variable sections can reduce energy losses when transmitting reactive power by over 90%. For three- and four-section static capacitors, the loss reduction is close to 100%. The reduction in energy losses increases when approaching maximal levels of annual reactive load. Energy losses in electrical grid systems can be reduced by capacitor batteries with no more than three or four variable sections. In most cases, this can be achieved by two-section capacitor batteries.