检索结果-内蒙古大学图书馆

The centrifugal acceleration and the Y-point of the Pulsar Magnetosphere

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Shibata, Shinpei Kisaka, Shota Faculty of Science Yamagata University Kojirakawa 1-4-12 Yamagata990-8560 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan

We investigate the centrifugal acceleration in an axisymmetric pulsar magnetosphere under the ideal-MHD approximation. We solved the field-aligned equations of motion for flows inside the current sheet with finite thickness. We find that flows coming into the vicinity of a Y-point become super fast. The centrifugal acceleration takes place efficiently, and most of the Poynting energy is converted into kinetic energy. However, the super fast flow does not provide enough centrifugal drift current to open the magnetic field. Opening of the magnetic field is possible by the plasmas that are accelerated in the azimuthal direction with a large Lorentz factor in the closed field region. We find that this acceleration takes place if the field strength increases toward the Y-point from inside. The accelerated plasma is transferred from the closed field region to the open field region by magnetic reconnection with plasmoid emission. We also estimate the Lorentz factor to be reached in the centrifugal wind. © 2024, CC BY.

关键词： Magnetohydrodynamics

Enhancement of superconductivity in the Fibonacci chain

学校读者我要写书评

暂无评论

Physical Review B 2024年第13期109卷 134504-134504页

作者： Meng Sun Tilen Čadež Igor Yurkevich Alexei Andreanov School of Physics and Optoelectronic Engineering Beijing University of Technology Beijing 100124 China Center for Theoretical Physics of Complex Systems Institute for Basic Science Daejeon 34126 Republic of Korea School of Computer Science and Digital Technologies Aston University Birmingham B4 7ET United Kingdom Basic Science Program Korea University of Science and Technology Daejeon 34113 Republic of Korea

We study the interplay between quasiperiodic disorder and superconductivity in a one-dimensional tight-binding model with the quasiperiodic modulation of on-site energies that follow the Fibonacci rule, and all the eigenstates are multifractal. As a signature of multifractality, we observe the power-law dependence of the correlation between different single-particle eigenstates as a function of their energy difference. We numerically compute the mean-field superconducting transition temperature for every realization of a Fibonacci chain of a given size and find the distribution of critical temperatures, analyze their statistics, and estimate the mean value and variance of critical temperatures for various regimes of the attractive coupling strength and quasiperiodic disorder. We find an enhancement of the critical temperature compared to the analytical results that are based on strong assumptions of the absence of correlations and self-averaging of multiple characteristics of the system, which are not justified for the Fibonacci chain. For the very weak coupling regime, we observe a crossover where the self-averaging of the critical temperature breaks down completely and strong sample-to-sample fluctuations emerge.

关键词： Superconductivity Fractals Mean field theory Methods in superconductivity Tight-binding model

Modeling Atomistically Assembled Diffractive Optics in Solids

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Kling, Trevor Na, Dong-Yeop Hosseini, Mahdi Department of Electrical and Computer Engineering Applied Physics Program Northwestern University EvanstonIL60208 United States Department of Electrical Engineering Pohang University of Science and Technology Pohang37673 Korea Republic of Elmore Family School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States

We develop a model describing long-range atom-atom interactions in a two-dimensional periodic or a-periodic lattice of optical centers inside a solid-state host material. We consider realistic environmental and technical conditions such as frequency and position broadening. Even when considering a significant frequency broadening in the ensemble (∼300 GHz), we observe up to a three-fold increase in directional scattering from the resonant lattice in a system. The model can be used to scalably design quantum optical elements, e.g. a quantum lens, harnessing atomistic engineering (e.g. via ion implantation) of collective interactions in materials to enhance quantum properties. © 2024, CC BY.

关键词： Nanocrystals

Development of Indigenous Pulse-Shape Discrimination Algorithm for Organic Scintillation detectors

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Karmakar, Annesha Kumar, G. Anil Bhavika Anand, V. Pal, Anikesh Nuclear Engineering and Technology Program Department of Mechanical Engineering Indian Institute of Technology-Kanpur India Radiation Detectors and Spectroscopy Laboratory Department of Physics Indian Institute of Technology Roorkee India Department of Mechanical Engineering Indian Institute of Technology-Kanpur India

The use of programmable hardware devices is imperative for digital based pulse shape discrimination (PSD) to differentiate between various types of radiation. This work reports the development of a PSD algorithm based on tail area and total area, eliminating the need for programmable hardware. The pulses were collected using BC501 detector and Pu-Be source from a digitizer in the oscilloscope mode. The algorithm performs crucial functions such as pulse normalization, shaping, identification and removal of multiple peaks and threshold determination. The algorithm provides neutron and γ-ray counts, scatter plot, and FoM. In order to test the efficacy of our proposed algorithm, pulses were collected from a different source-detector setup comprising BC501A detector and an Am-Be source from a digitizer in the oscilloscope mode and Charge Integration (CI) mode. The results obtained from our proposed algorithm and CI method clearly indicates a good agreement in terms of number of neutrons and γ-rays and Figure-of-Merit (FoM), thus providing cost-effective alternative method for neutron and γ-ray discrimination, offering flexibility and accuracy without specialized hardware. © 2023, CC BY.

关键词： Gamma rays

Calibration free, time-resolved diffuse optical spectroscopy using combined monte-carlo and diffusion theory 11

学校读者我要写书评

暂无评论

Calibration free, time-resolved diffuse optical spectroscopy...

Biomedical Applications of Light Scattering XI 2021

作者： Helton, Michael McMaster, Carter Mycek, Mary-Ann Vishwanath, Karthik Applied Physics Program University of Michigan Ann Arbor United States Department of Physics Miami University OxfordOH45056 United States Biomedical Engineering Department University of Michigan Ann Arbor United States

ISBN: (数字)9781510641501

ISBN: (纸本)9781510641495

Near-infrared spectroscopy has been widely employed in biophotonics to study and quantify the optical properties of biological tissues. Unlike steady-state approaches, time-resolved spectroscopic techniques enable optical absorption and scattering properties of the medium to be separated, allowing for quantitation of depth-dependent absolute tissue optical properties. However, robust analysis of time-resolved signals requires careful consideration of calibration techniques and computational models. Here, we consider the effect of the time window employed when fitting a diffusion theory model to Monte-Carlo simulations. Next, we describe the impact of the temporal position of the instrument response function (IRF) in recovery of the optical properties. Finally, we discuss a technique to analyze time-resolved measurements without knowledge of the timescale of the IRF or the time-resolved measurement byfitting the relative shape of the photons' distribution time-of-flight (DTOF). © 2021 SPIE. All rights reserved.

关键词： Near infrared spectroscopy

Emergent dimer-model topological order and quasi-particle excitations in liquid crystals: combinatorial vortex lattices

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Meng, Cuiling Wu, Jin-Sheng Kos, Žiga Dunkel, Jörn Nisoli, Cristiano Smalyukh, Ivan I. Department of Physics and Chemical Physics Program University of Colorado BoulderCO80309 United States Hiroshima University Hiroshima Higashihiroshima Japan Department of Mathematics Massachusetts Institute of Technology CambridgeMA02139 United States Faculty of Mathematics and Physics University of Ljubljana Ljubljana Slovenia Department of Condensed Matter Physics Jožef Stefan Institute Ljubljana Slovenia Theoretical Division Physics of Condensed Matter and Complex Systems Center For Nonlinear Studies Los Alamos National Laboratory Los AlamosNM87545 United States Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States

Liquid crystals have proven to provide a versatile experimental and theoretical platform for studying topological objects such as vortices, skyrmions, and hopfions. In parallel, in hard condensed matter physics, the concept of topological phases and topological order has been introduced in the context of spin liquids to investigate emergent phenomena like quantum Hall effects and high-temperature superconductivity. Here, we bridge these two seemingly disparate perspectives on topology in physics. Combining experiments and simulations, we show how topological defects in liquid crystals can be used as versatile building blocks to create complex, highly degenerate topological phases, which we refer to as ‘Combinatorial Vortex Lattices’ (CVLs). CVLs exhibit extensive residual entropy and support locally stable quasi-particle excitations in the form of charge-conserving topological monopoles, which can act as mobile information carriers and be linked via Dirac strings. CLVs can be rewritten and reconfigured on demand, endowed with various symmetries, and modified through laser-induced topological surgery — an essential capability for information storage and retrieval. We demonstrate experimentally the realization, stability, and precise optical manipulation of CVLs, thus opening new avenues for understanding and technologically exploiting higher-hierarchy topology in liquid crystals and other ordered media. Copyright © 2025, The Authors. All rights reserved.

关键词： Laser surgery

Low Cost Muon Telescope (LOCOMOTE) 38

学校读者我要写书评

暂无评论

Low Cost Muon Telescope (LOCOMOTE)

38th International Cosmic Ray Conference, ICRC 2023

作者： Huang, Nai-Cheng Lin, Guey-Lin Lai, Kwang-Chang Huang, M.A. Liu, T.C. Institute of Physics National Yang Ming Chiao Tung University Hsinchu City Taiwan Center for General Education Chang Gung University Taoyuan City Taiwan Department of Energy Engineering National United University Taiwan Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu City Taiwan Department of applied physics National PingTung university PingTung City Taiwan Undergraduate Degree Program of Systems Engineering and Technology National Yang Ming Chiao Tung University Hsinchu City Taiwan Chung Cheng Institute of Technology National Defense University Taoyuan Taiwan Leung Center for Cosmology and Particle Astrophysics National Taiwan University Taipei Taiwan

Low Cost Muon Telescope (LOCOMOTE) is a low-cost charged particle detector. Each LOCOMOTE unit includes two pieces of BC408 (2"*2"*1") scintillators, silicon photomultipliers (SiPM), and digital logic circuits. The cost of each LOCOMOTE unit is approximately 200 US dollars and is mainly used as a teaching instrument for high school students in cosmic ray education. Each LOCOMOTE unit can be connected to the network, and data from different units can form a ground array to measure high-energy cosmic ray events. In this report, we present the performance verification of the telescope, including the measurement of cosmic muon angular flux and the feasibility of muon tomography using multiple telescopes. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Telescopes

Low-loss, nonvolatile tuning of Bragg structures with Sb2Se3

学校读者我要写书评

暂无评论

Low-loss, nonvolatile tuning of Bragg structures with Sb2Se3

CLEO: Applications and Technology in CLEO 2024, CLEO: A and T 2024 - Part of Conference on Lasers and Electro-Optics

作者： Nobile, Nicholas A. Lian, Chuanyu Sun, Hongyi Huang, Yi-Siou Mills, Brian Popescu, Cosmin Constantin Callahan, Dennis Hu, Juejun Ríos Ocampo, Carlos A. Youngblood, Nathan Electrical & Computer Engineering Department University of Pittsburgh PittsburghPA15213 United States Department of Materials Science & Engineering University of Maryland College ParkMD20742 United States Institute for Research in Electronics and Applied Physics University of Maryland College ParkMD20742 United States Department of Materials Science & Engineering Massachusetts Institute of Technology CambridgeMA02139 United States Draper Scholar Program The Charles Stark Draper Laboratory Inc. CambridgeMA02139 United States The Charles Stark Draper Laboratory Inc. CambridgeMA02139 United States

Sb2Se3 is used to switch between broadband transparency and enhanced index contrast in two device types leveraging Bragg gratings for tunable stop- and pass-band functionalities. Experimental results highlight fabrication challenges and efficacy of the designs. © Optica Publishing Group 2024, © 2024 The Author(s)

关键词：

The effect of lard concentration and ozonation on changes in polarization angle of olive oil 10

学校读者我要写书评

暂无评论

The effect of lard concentration and ozonation on changes in...

10th International Seminar on New Paradigm and Innovation of Natural Sciences and itsApplication, ISNPINSA 2020

作者： Saputra, F.A. Azam, M. Arianto, F. Sofjan, K.F. Sugito, H. Alkian, I. Department of Physics Faculty of Science and Mathematics Diponegoro University Semarang50275 Indonesia Study Program of Automation Engineering Technology Vocational School Diponegoro University Indonesia

This research aims to analyze the effect of ozone exposure time and lard mixture on the polarization angle of transmission of olive oil. The study uses a transmission polarization method with a laser (λ = 532 nm) as a light source. The research sample in the form of olive oil mixed with lard at a concentration of 10, 20, 40, and 80%, with an ozone exposure time of 0-30 minutes. The sample is subjected to external electric fields with variations from 0-4.5 x 102 kV/m to increase the change's polarization angle. The results showed that the change in polarization angle would change linearly with the increase in lard concentration with olive oil. Olive oil with a low concentration of lard (10%) experienced an increase in the change in polarization angle with a value of 0.31 due to the effect of 90 minutes of ozone exposure. In general, the results of the study showed that increased concentrations of lard, ozone exposure time, electric field strengths caused an increase in changes in the polarization angle in a mixture of olive oil and lard. © Published under licence by IOP Publishing Ltd.

关键词： Mixtures