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Strong coupling of magnetization dynamics of two antiferromagnetic layers by phonons 声子对两个反铁磁层磁化动力学的强耦合
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.21617
Strong and long-range coupling of the magnetization dynamics of the two antiferromagnetic layers mediated by the phonons transferred through a nonmagnetic insulator has been investigated. The magnetization dynamics in one of the antiferromagnetic layers via a magnetoelastic interaction leads to the excitation of phonons and their pumping to the nonmagnetic layer. The transfer of phonons, which carry angular momentum, through a nonmagnetic insulator from one antiferromagnetic layer to another, leads to an interference pattern in the absorption spectrum, which represents the coupling of magnetization dynamics of two layers.
研究了通过非磁性绝缘体传递的声子介导的两个反铁磁层磁化动力学的强和远程耦合。其中一个反铁磁层中的磁化动力学通过磁弹性相互作用导致声子的激发和它们向非磁性层的泵送。携带角动量的声子通过非磁性绝缘体从一个反铁磁层转移到另一个反铁磁层,导致吸收光谱中的干涉图案,这代表了两层磁化动力学的耦合。
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引用次数: 0
Investigation of electromagnetic oscillations and their instabilities in a nonuniform quantum electron-positron magnetoplasma interacting with a short pulse laser 短脉冲激光作用下非均匀量子电子-正电子磁等离子体的电磁振荡及其不稳定性研究
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.81566
In this article, we investigated electromagnetic oscillations in a quantum nonuniform electron-positron magnetoplasm interacting with a short pulse laser, in low frequency approximation, in two parallel and perpendicular directions. According to our investigations, the waves in the parallel direction are affected by ponderomotive force, vigorously. Quantum corrections cause the magnitude of this force to change and accordingly, cause the magnitude of phase and group velocities of the waves, as well as, their instability to change. In the parallel direction, initial quantities of number density and streaming velocity affect the waves directly, but the magnetic field affects these waves through the ponderomotive force, indirectly. As well, absorption of the laser pulse causes the plasma waves to grow in the laser direction and damp in the opposite direction. While, the amplification of the laser causes the waves to damp in the laser direction and grow in the opposite direction. In the perpendicular direction, the waves are influenced by the transverse gradient of initial quantities of number density, streaming velocity and external magnetic, in addition to their amounts, while these gradients don't have any effect on the parallel waves. Likewise, we investigate the behavior of the waves for different values of the transverse gradients. So that we indicate that the presence of each of gradients can completely change the behavior of the waves. As well, the investigations indicated that the presence of the transverse gradient of the initial density or streaming velocity couldn’t create the electromagnetic waves in the perpendicular direction but, the transverse gradient of the magnetic field could initiate these waves.
在本文中,我们研究了量子非均匀电子-正电子磁质与短脉冲激光在低频近似下,在两个平行和垂直方向上的电磁振荡。根据我们的研究,平行方向的波受到有质动势的强烈影响。量子修正导致这个力的大小改变,相应地,导致波的相速度和群速度的大小,以及它们的不稳定性改变。在平行方向上,数密度和流速度的初始量直接影响波,而磁场通过质动势间接影响波。同样,激光脉冲的吸收导致等离子体波在激光方向上增长,而在相反方向上衰减。然而,激光的放大使波在激光方向上受潮,并在相反的方向上增长。在垂直方向上,波除数量外,还受数密度、流速度和外磁初始量的横向梯度的影响,而这些梯度对平行波没有影响。同样,我们研究了不同横向梯度值下波的行为。所以我们指出,每一个梯度的存在都可以完全改变波的行为。此外,研究表明,初始密度或流速度的横向梯度的存在不能产生垂直方向的电磁波,而磁场的横向梯度可以引发垂直方向的电磁波。
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引用次数: 0
Calculation of photon absorbed dose kernel in a homogeneous water phantom by Monte Carlo Geant4 toolkit 用Monte Carlo Geant4工具计算均匀水影中光子吸收剂量核
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.81563
Nowadays, convolution/superposition(C/S) is used to calculate absorbed dose distribution by using the absorbed dose kernel(ADK). ADK describes the absorbed dose distribution per number of interaction at a small volume around the point of photon interaction. The purpose of this study is to calculate ADK and investigate its angular and radial behavior. In this study, ADK is calculated in a homogeneous water phantom in the polar coordinates by using the Monte Carlo Geant4 toolkit for monoenergetic photons with energies in the range 0.3MeV-5MeV. To study accurately, ADK is divided into several groups in order of produced charged particle set in motion at each photon interaction. Our result shows ADK rapidly decreases as the polar angle, with respect to the incident photon direction, is increased. As the radial distance from the interaction point increases, ADK is raised and then strongly decreased. ADK is symmetrically distributed around the point of interaction for low incident photon energy while forward distributed for high incident energy photons.
目前,利用吸收剂量核(ADK),采用卷积/叠加(C/S)法计算吸收剂量分布。ADK描述了在光子相互作用点周围的小体积内每次相互作用的吸收剂量分布。本研究的目的是计算ADK并研究其角和径向行为。在本研究中,利用Monte Carlo Geant4工具对能量在0.3MeV-5MeV范围内的单能光子在极坐标系下的均匀水影中计算了ADK。为了准确地研究,我们按照产生的带电粒子在每次光子相互作用中运动的顺序将ADK分为几组。结果表明,相对于入射光子方向的极角增大,ADK迅速减小。随着距相互作用点径向距离的增加,ADK先升高后急剧降低。对于低入射光子能量,ADK沿相互作用点对称分布;对于高入射光子,ADK沿相互作用点正向分布。
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引用次数: 0
Calculation of thermal conductivity of UO2±0.25 solving phonon Boltzmann equation UO2±0.25解声子玻尔兹曼方程的导热系数计算
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.51457
In this study, the effect of point defects on the thermal conductivity of UO2 is investigated. Especially, the effects of oxygen vacancy and interstitial are considered. Thermal conductivity of UO2, UO2+0.25 and UO2-0.25 is calculated by solving the phonon Boltzmann equation (BTE) under the relaxation time approximation (RTA). The results show that introducing any defects to the lattice structure of UO2 decreases thermal conductivity significantly. In addition, the results show that the variation of the thermal conductivity of UO2-0.25 is much lower than that of UO2+0.25 in the temperature interval of 300 to 1000 Kelvin.
本文研究了点缺陷对UO2热导率的影响。特别考虑了氧空位和间隙的影响。利用弛豫时间近似(RTA)求解声子玻尔兹曼方程(BTE),计算了UO2、UO2+0.25和UO2-0.25的导热系数。结果表明,在UO2的晶格结构中引入任何缺陷都会显著降低其导热系数。此外,结果表明,在300 ~ 1000开尔文的温度区间内,UO2-0.25的导热系数变化远小于UO2+0.25。
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引用次数: 0
Investigation and optimization of electron gun beam, based on simulation and experimental results 基于仿真和实验结果的电子束研究与优化
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.71539
Nowadays, by expanding the application of thin layers in industry and medical sciences, their fabrication methods have also received attention. One of those methods is the vaporizing material method with the help of an electron gun. The most important part in the electron gun is the electron optic, which is responsible for producing and accelerating electrons, so that it becomes possible to vaporize refractory materials in a shorter period of time by better modifying and controlling the electron beam (the shape and diameter of the electron beam) at the target location. The reduction and control of the beam diameter in this evaporation source depends on various parameters such as device geometry, magnetic field intensity, electric power, etc. Therefore, in this research, the effect of those parameters was investigated by conducting experiments and using finite element and modeling software. The simulation results revealed that the effect of the effective parameters on the beam diameter can be predicted to a good extent, so that the diameter of the electron beam decreases by changing the geometrical shape, size and displacement of the output beam components. Then, the new electron gun, compared to the existing prototype, is optimized by applying these changes in the construction of the device and conducting experiments, and its beam diameter is reduced by 40% to be more focused.
近年来,随着薄层材料在工业和医学上的广泛应用,薄层材料的制备方法也受到了人们的关注。其中一种方法是借助电子枪使材料汽化。电子枪中最重要的部分是电子光学,它负责产生和加速电子,通过在目标位置更好地修改和控制电子束(电子束的形状和直径),使耐火材料在更短的时间内汽化成为可能。该蒸发源中光束直径的减小和控制取决于器件几何形状、磁场强度、电功率等各种参数。因此,在本研究中,通过实验并使用有限元和建模软件来研究这些参数的影响。仿真结果表明,可以很好地预测有效参数对电子束直径的影响,从而通过改变输出光束组件的几何形状、尺寸和位移来减小电子束直径。然后,与现有原型相比,将这些变化应用于器件的构造和实验中,对新电子枪进行了优化,其光束直径减小了40%,更加聚焦。
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引用次数: 0
Improving corrosion resistance of aluminum by zirconium carbide thin films 碳化锆薄膜提高铝的耐蚀性
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.91579
In this paper, zirconium carbide (ZrC) thin films were deposited on glass and aluminum substrates using DC magnetron sputtering. It was found that different ratios of acetylene gas (C2H2, as a reactive gas) in the gas mixture of acetylene and argon (Ar, as a sputtering gas) affect the microstructural properties, corrosion behavior, and protection efficiency of ZrC thin films. X-ray diffraction (XRD) was used to characterize the microstructural properties of thin films. The corrosion behavior of thin films in a 3.5% NaCl solution was evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS). FESEM was also employed to examine thin films' surface morphology and thickness.
本文采用直流磁控溅射技术在玻璃和铝衬底上制备了碳化锆薄膜。研究发现,在乙炔与氩气(溅射气体为Ar)混合的气体中,不同比例的乙炔气体(反应气体为C2H2)会影响ZrC薄膜的显微组织性能、腐蚀行为和保护效率。采用x射线衍射(XRD)对薄膜的微观结构进行了表征。采用动电位极化试验和电化学阻抗谱(EIS)评价了薄膜在3.5% NaCl溶液中的腐蚀行为。利用FESEM对薄膜的表面形貌和厚度进行了检测。
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引用次数: 0
Quantum transport in the Ising chain: global vs local approach Ising链中的量子输运:全局vs局部方法
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.11598
We study energy and spin transport in a one-dimensional Ising chain which is connected to two separate heat baths on both sides. By applying the Born-Markov approximation, within the global approach, we derive the Markovian master equation of the system, and also the explicit form of the Lindblad operators and the steady state. Thereafter, we investigate the behavior of energy and spin dynamics of the system in the global regime. Finally, we solve the problem with the local approach, and we show that the results are not the same for both approaches.
我们研究了一维伊辛链中的能量和自旋输运,它连接到两侧的两个独立的热浴。通过应用Born-Markov近似,在全局方法内,我们导出了系统的马尔可夫主方程,以及Lindblad算子和稳态的显式形式。然后,我们研究了系统在全局状态下的能量和自旋动力学行为。最后,我们用局部方法解决了这个问题,并证明了两种方法的结果并不相同。
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引用次数: 0
Hierarchy problem in the Standard Model and extended Higgs potential with scale symmetry 标准模型中的层次问题和具有尺度对称的扩展希格斯势
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.11627
In this research we introduce a model by adding two singlet scalars to the Higgs potential of the Standard Model and imposing scale symmetry to address the hierarchy problem. The scale symmetry plays a crucial role here. In the classical limit, all the scalars are massless. Only one of the singlet scalars and the Higgs doublet acquire non-zero expectation value. After diagonalization of the mass matrix, we have a massless singlet scalar, the so-called scalon, and two massive scalars. From quantum corrections, the scalon gets mass. Besides theoretical constraints on the parameters of the model, we impose bounds on the triple Higgs interactions provided by ATLAS and CMS detectors at the LHC.
在本研究中,我们通过在标准模型的希格斯势中加入两个单重态标量并施加尺度对称来引入一个模型来解决层次问题。尺度对称在这里起着至关重要的作用。在经典极限中,所有标量都是无质量的。单重态标量和希格斯双重态中只有一个得到非零期望值。在质量矩阵对角化之后,我们有一个无质量单重标量,也就是所谓的标量,和两个大质量标量。从量子修正中,标量得到质量。除了对模型参数的理论约束外,我们还对大型强子对撞机上ATLAS和CMS探测器提供的三重希格斯相互作用施加了限制。
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引用次数: 0
Nonlinear brain dynamics in neural field model and harmonic generation responses to the external stimuli 神经场模型中的非线性脑动力学及对外界刺激的谐波产生反应
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.11595
The most important nonlinear feature in the EEG response to external stimuli is the harmonic generation and entrainment which is due to the interaction between stimuli and ongoing brain oscillations. In this paper, we study the nonlinear brain dynamics and harmonic generation responses to the periodic external stimuli by employing continuum neural field model. A compact dynamical model of brain activity is first introduced, and the governing equations for the evolution of potential are obtained. Then, using the perturbation method and multiple time scales, we show brain response oscillations in harmonic drive frequency consistent with the recorded scalp EEGs from awake human subjects. Finally, to confirm the experimentally observed results of interaction between photic driving and brain dynamics, we have numerically simulated the full neural field model equations, and have shown harmonic frequency generation over a range of external frequencies.
在脑电对外部刺激的响应中,最重要的非线性特征是谐波的产生和携带,这是由于刺激和持续的脑振荡之间的相互作用。本文采用连续神经场模型研究了周期性外部刺激下的非线性脑动力学和谐波产生响应。首先介绍了一个紧凑的脑活动动力学模型,得到了脑电位演化的控制方程。然后,采用摄动法和多时间尺度,我们显示了与清醒受试者记录的头皮脑电图一致的谐波驱动频率下的大脑反应振荡。最后,为了证实光驱动与脑动力学之间相互作用的实验观察结果,我们对全神经场模型方程进行了数值模拟,并展示了在一定频率范围内谐波频率的产生。
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引用次数: 0
Study of hadron production through pair annihilation in the noncommutative standard model 非交换标准模型中通过对湮灭产生强子的研究
Q4 Physics and Astronomy Pub Date : 2023-06-01 DOI: 10.47176/ijpr.23.1.81550
Different scattering processes have been yet studied in the noncommutative standard model (SM) and different limits on the noncommutative scale have been determined. In the present work we, for the first time, study the hadron production process through pair annihilation, in the noncommutative standard model. In the experimental studies of hadron production through pair annihilation a wide range of collision energy spectrum () has been considered. In our study, we restrict ourselves to the ranges so having available experimental data from Belle Collaboration for B-meson production in the process we shall determine a lower limit for the noncommutative scale. In fact, by studying the effect of noncommutativity on the differential cross section at the parton level () as well as the fragmentation function of meson and comparing the theoretical results and experimental data the lower limit will be determined. Having analytical results for the pair annihilation cross section in the noncommutative SM it would be possible to specify the production cross section of each meson or baryon for various values of noncommutative scale.
在非交换标准模型(SM)中研究了不同的散射过程,并确定了非交换尺度的不同极限。本文首次在非交换标准模型中研究了通过对湮灭产生强子的过程。在对湮灭产生强子的实验研究中,考虑了大范围的碰撞能谱()。在我们的研究中,我们将自己限制在这个范围内,因此有了Belle协作公司提供的b介子产生过程的实验数据,我们将确定非交换尺度的下限。实际上,通过研究非交换性对部分子能级微分截面()以及介子的碎片函数的影响,并将理论结果与实验数据进行比较,就可以确定下限。有了非对易SM中对湮灭截面的分析结果,就有可能确定各种非对易尺度值下每个介子或重子的产生截面。
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引用次数: 0
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Iranian Journal of Physics Research
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