共查询到17条相似文献,搜索用时 109 毫秒
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本文对球形演化的夸克–胶子等离子体膨胀源进行了2π干涉学分析.夸克–胶子等离子体的演化由相对论流体力学和熵密度的物态方程描述,而2πHanbury-Brown-Twiss(HBT)关联函数由量子几率振幅的路径积分公式计算.研究结果表明,由2π干涉学得到的源的空间参量敏感地依赖于π介子发射源的相空间分布,源的膨胀速度导致HBT半径变小,并会改变HBT半径与冻结温度之间的关系. 相似文献
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利用相对论量子分子动力学模型 RQMD,对 RHIC能区 s =2 0 0 AGe VAu+ Au中心碰撞进行了 2 π干涉学分析,对 HBT关联相干因子 λ的行为进行了研究 .研究表明 ,参数 λ一般小于理想混沌源时的值,这反映了源的部分相干特性外 ,还与源的膨胀和持续冻结有关 ,体现为 λ参数对粒子的冻结时间较为敏感.Using the dynamical transport model RQMD with a correlation after burner, the behavior of two pion HBT λ parameter is studied in Au+Au central collisions at RHIC energy s=200 A GeV. The λ parameter is found to be sensitive to the sequential freeze out in heavy ion collisions. 相似文献
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应用量子路径积分的方法,分析了高能重离子碰撞产生的高重子数密度粒子发射源的2K和2π干涉学(hanbury Brown Twiss,HBT关联)。利用相对论流体动力学描述源的演化,采用的状态方程包含QGP到强子相的一级相变和对强子气体的体积修正。在2π关联的计算中考虑了激发态粒子衰变和多重散射效应,并将其HBT关联半径和寿命与传统热冻结模型的结果进行了对比。计算表明,早期化学冻结产生的K介子的HBT关联半径比2π关联的HBT关联半径小。激发态粒子的衰变使HBT关联半径和寿命增加,而多重散射对HBT关联的结果几乎没有影响。Using quantum path integral formulae, we examined the two kaon and two pion Hanbury Brown Twiss (HBT) interferometry for the particle emitting source with high baryon density. The evolution of the source is described by relativistic hydrodynamics. We use an equation of state of first order transition from QGP to hadronic phase and consider a volume correction for the hadronic gas. The two pion HBT results with effects of excited particle decay and multiple scattering were investigated and compared with those for conventional thermal freeze out (TFO) model. We found that the two kaon HBT radius was smaller than those of the two pion interferometry. The particle decay increases the HBT radius and lifetime, while the effect of multiple scattering on HBT results can be neglected. 相似文献
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研究了电磁波沿轴向对称柱形等离子体天线传播的特性、色散关系及辐射方向图、增益等天线参数.通过对腔体材料介电系数、内外半径、等离子体密度、碰撞频率等参数的分析,结果表明要减小波沿等离子体天线传播的衰减,应当增加等离子体密度,减小碰撞频率,增加等离子体半径,减小腔体厚度,采用介电系数较小的材料.计算了在不同参数条件下,等离子体天线的辐射方向图、增益的变化,这些结果对于等离子体天线的设计很有参考价值.
关键词:
等离子体天线
色散关系
增益
辐射方向图 相似文献
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基于空泡生长和溃灭理论分析不同环境压强对空泡膨胀的最大泡半径、收缩的最小泡半径、膨胀与收缩速度的影响.同时,利用高功率激光与液体物质相互作用产生空泡,采用高速照相机、高频测量水听器实验研究不同环境压强下液体中空泡运动规律,并将实验结果与计算结果进行对比.结果表明:环境压强对空泡脉动特性有较大影响.相同激光能量击穿液体介质时,随着外界环境压强的增加,空泡脉动周期呈现递减趋势;空泡第一次脉动的最大泡半径同脉动周期的变化趋势一致,且数值由快到慢递减;随着外界压强的增加,空泡溃灭的速度越快.随着压强的增大,空泡膨胀与收缩更为剧烈,持续时间更短. 相似文献
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将SOI技术优势引入SiGe HBT,可满足当前BiCMOS高速低功耗的应用需求.SOI SiGe HBT作为BiCMOS工艺的核心器件,其频率特性决定了电路所能达到的工作速度.为此,本文针对所提出的SOI SiGe HBT器件结构,重点研究了该器件的频率特性,并通过所建立的集电区电容模型予以分析.规律和结果为:1)SOI SiGe HBT特征频率随集电区掺杂浓度的升高而增加;2)SOI SiGe HBT特征频率与集电极电流IC之间的变化规律与传统SiGe HBT的相一致;3)正常工作状态,SOI SiGe HBT(集电区3×1017cm-3掺杂)最高振荡频率fmax大于140 GHz,且特征频率fT大于60 GHz.与传统SiGe HBT相比,特征频率最大值提高了18.84%.以上规律及结论可为SOI SiGe HBT及BiCMOS的研究设计提供重要依据. 相似文献
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We examine the two-pion Hanbury-Brown-Twiss (HBT) interferometry for the particle-emitting source produced in heavy ion collisions at HIRFL-CSR energy. The source evolution is described by relativistic hydrodynamics with three kinds of equations of state for chemical equilibrium (CE), chemical freeze-out (CFO),and partial chemical equilibrium (PCE) models, respectively. We investigate the effects of particle decay,multiple scattering, and source collective expansion on the two-pion interferometry results. We find that the HBT radii of the evolution source for the CFO and PCE models are smaller than that for the CE model.The HBT lifetime for the CFO model is smaller than those for the PCE and CE models. The particle decay increases the HBT radius and lifetime while the source expansion decreases the HBT radius. The multiple scattering effect on the HBT results can be neglected based on our model calculations. 相似文献
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We examine the two-pion Hanbury-Brown-Twiss (HBT) interferometry for the particle-emitting source produced in heavy ion collisions at HIRFL-CSR energy. The source evolution is described by relativistic hydrodynamics with three kinds of equations of state for chemical equilibrium (CE), chemical freeze-out (CFO), and partial chemical equilibrium (PCE) models, respectively. We investigate the effects of particle decay, multiple scattering, and source collective expansion on the two-pion interferometry results. We find that the HBT radii of the evolution source for the CFO and PCE models are smaller than that for the CE model. The HBT lifetime for the CFO model is smaller than those for the PCE and CE models. The particle decay increases the HBT radius and lifetime while the source 相似文献
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The space-time evolution of the (1+1)-dimensional viscous hydrodynamics with an initial quark-gluon plasma (QGP) produced in ultrarelativistic heavy ion collisions is studied numerically. The particle-emitting sources undergo a crossover transition from the QGP to hadronic gas. We take into account a usual shear viscosity for the strongly coupled QGP as well as the bulk viscosity which increases significantly in the crossover region. The two-pion Hanbury-Brown-Twiss (HBT) interferometry for the viscous hydrodynamic sources is performed. The HBT analyses indicate that the viscosity effect on the two-pion HBT results is small if only the shear viscosity is taken into consideration in the calculations. The bulk viscosity leads to a larger transverse freeze-out configuration of the pion-emitting sources, and thus increases the transverse HBT radii. The results of the longitudinal HBT radius for the source with Bjorken longitudinal scaling are consistent with the experimental data. 相似文献
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HBT参数对π源空间分布的敏感性研究(英文) 总被引:1,自引:1,他引:0
利用理想高斯源的两粒子关联函数,对单高斯源和双高斯源的两π介子HBT关联效应进行了研究,得出了相应的半径参数和A参数.结果表明,半径参数主要取决于高能重离子碰撞中多数π介子产生的中间区域;对产生π介子的边缘区域的空间分布形状不敏感.在边缘区域内产生的π介子主要影响A参数的变化.π介子源空间分布的非高斯形是导致λ参数减少的一个重要因素.The HBT radius parameters and the HBT λ-parameters of single Gaussian source and double Gaussian source are investigated by using two-pion correlation function in HBT intensity interferometry. It is indicated that the radius parameter is insensitive to the spatial shape of the edge zone of source and is mainly affected by the size of the central zone of pions emitted in high energy heavy-ion collisions. The pions produced at the edge of source influence the λ parameter. The non-Gaus... 相似文献
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We give the formulas of two-pion Hanbury-Brown-Twiss (HBT) correlation function for a partially coherent evolution pion-emitting source,using quantum probability amplitudes in a path-integral formalism.The multiple scattering of the particles in the source is taken into consideration based on Glauber scattering theory.Two-pion interferometry with effects of the multiple scattering and source collective expansion is examined for a partially coherent source of hadronic gas with a finite baryon density and evolving hydrodynamically.We do not find observable effect of either the multiple scattering or the source collective expansion on HBT chaotic parameter. 相似文献
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We give the formulas of two-pion Hanbury-Brown-Twiss (HBT) correlation function for a partially coherent evolution pion-emitting source, using quantum probability amplitudes in a path-integral formalism. The multiple scattering of the particles in the source is taken into consideration based on Glauber scattering theory. Two-pion interferometry with effects of the multiple scattering and source collective expansion is examined for a partially coherent source of hadronic gas with a finite baryon density and evolving hydrodynamically. We do not find observable effect of either the multiple scattering or the source collective expansion on HBT chaotic parameter. 相似文献
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Wei-Ning Zhang 《Physics of Particles and Nuclei Letters》2011,8(9):977-980
A review on the two-pion Hanbury-Brown—Twiss (HBT) interferometry in the granular source model of quark-gluon plasma droplets
is presented. The characteristic quantities of the granular source extracted by imaging analysis are presented and compared
with the HBT radii obtained by the usual Gaussian formula fit. The signals of granular sources are presented. 相似文献