共查询到20条相似文献,搜索用时 234 毫秒
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本文介绍了利用蒙特卡罗粒子输运程序MCNPX2.5.0进行中国散裂中子源多功能反射谱仪屏蔽设计的屏蔽需求、辐射源项、计算方法和设计结果等内容.在计算中考虑慢化器泄漏源项、中子导管损失源项等不同辐射源项,使用分步计算和源项角度偏移、源项能量偏移、几何分裂等多种减方差方法,在保证计算结果精度的同时提高计算速度.在谱仪束线传输段、第二中子开关、散射室等的屏蔽计算中,通过比较了不同条件下的所需屏蔽确定最终屏蔽设计,确保谱仪屏蔽外人员可到达区域的剂量低于安全限值2.5μSv/h. 相似文献
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在考虑分子内原子间的几何屏蔽效应随电子入射能量变化的基础上, 提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的可加性规则修正方法. 利用这一修正后的可加性规则并使用“电子-C, H, O, N原子”散射总截面的实验数据, 在50—5000 eV内计算了电子被NO, N2O, NO2和C2H6分子散射的总截面, 且将计算结果与实验结果及其他理论结果进行了比较. 结果表明, 利用这一方法修正过的可加性规则进行计
关键词:
电子散射
可加性规则
总截面
几何屏蔽效应 相似文献
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本文将等离子体核聚变反应截面研究中利用等离子体环境涨落进行修正了的Debye-Hückel屏蔽势推广到计算等离子体中辐射离子束缚态的能级结构. 通过Tsallis参数q的变化,在等离子体辐射离子束缚态能级结构的计算中加入等离子体参数涨落的平均效应,即,等离子体动力学. 具体给出了利用修正的Debye-Hückel屏蔽势对类氦铝束缚态能级结构的计算结果. 结果表明基于这种修正的屏蔽势,自由电子的极化分布具有和线性Debye-Hückel屏蔽势不同的结构. 这种通过等离子体涨落分布对屏蔽势函数进
关键词:
等离子体中的原子结构
等离子体环境涨落
修正了的Debye-Hückel屏蔽势 相似文献
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针对复杂屏蔽腔体往往是由多个空间构成的实际情况, 本文构建了内置条状金属板的双层金属腔体物理解析模型, 将外层腔体的近场电磁干扰等效为电偶极子, 基于Bethe小孔耦合理论并利用推广的腔体格林函数推导了内腔体的电磁场分布的近似表达式. 利用该解析模型计算分析了条状金属板的位置和方向对屏蔽效能的影响. 通过计算结果与全波仿真软件CST仿真结果的对比, 证实了本文所建理论模型的有效性, 为复杂腔体屏蔽效能的快速计算提供了理论参考. 相似文献
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:用改进的屏蔽氢离子模型[1]计算了离子的电离势和次壳层能量。大量计算数据表明,改进模型计算的结果在低Z低离化时与实验相符;在高Z高离化时与MCDF的结果相符,从而弥补了R.M.More屏蔽氢离子模型、Slater单电子模型、WBEPM模型的不足。 相似文献
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The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations. 相似文献
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The next-to-leading order Debye screening mass in QGP is calculated by taking into account the damping rate of gluons in the formalism of real time finite temperature QCD, and the infrared singularity of the naive calculation is cured without adding a nonperturbative magnetic screening mass as a cutoff. In addition, the result is shown to be postive and gauge-independent, and is compared with the results from lattice simulations. 相似文献
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Based on a new screening Coulomb model, this paper discusses the effect of electron screening on proton capture reaction of 23Mg. The derived result shows that, in some considerable range of stellar temperatures, the effect of electron screening on resonant reaction is prominent; on the non-resonant reaction the effect is obvious only in the low stellar temperatures. The reaction rates of ^23Mg(p,γ) ^24Al would increase 15%-25% due to the fact that the electron screening are considered in typical temperature range of massive mass white dwarfs, and the results undoubtedly affect the nucleosynthesis of some heavier nuclei in massive mass white dwarfs. 相似文献
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从QED中光子传播子的Schweinger-Dyson方程出发,得到一个有用的德拜质量和热力学压强之间的关系.利用这个关系以及有限温度与有限化学势下的相关压强计算了德拜质量的双圈修正.其结果显示双圈修正减少了德拜屏蔽质量.最后还讨论了QED等离子体中的磁质量 相似文献
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E. Abdalla R. Banerjee C. Molina 《The European Physical Journal C - Particles and Fields》2000,17(3):467-471
We compute the quark–antiquark potential in three-dimensional massive quantum electrodynamics for an arbitrary fermion mass.
The result indicates that screening prevails for any quark masses, contrary to the classical expectations, generalizing our
previous result obtained for large masses. We also test the validity of several approximation schemes using a detailed numerical
analysis. The classical result is still reproduced for a small separation of the quarks.
Received: 16 May 2000 / Published online: 25 September 2000 相似文献
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The center of mass motion effect,on the quark delocalization model is to make the effective baryon-baryon (BB) interactions a lit tleless attractive but only a minor correction. The longrange behavior of the color screening potential is not critical for obtaining an intermediate attractive BB interaction. The cluster model and the molecular single quark-basis give exactly the same result. 相似文献
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M. Cheng S. Datta A. Francis J. van der Heide C. Jung O. Kaczmarek F. Karsch E. Laermann R. D. Mawhinney C. Miao S. Mukherjee P. Petreczky J. Rantaharju C. Schmidt W. Söldner 《The European Physical Journal C - Particles and Fields》2011,71(2):1-13
We present results for screening masses of mesons built from light and strange quarks in the temperature range of approximately between 140 MeV to 800 MeV. The lattice computations were performed with 2+1 dynamical light and strange flavors of improved (p4) staggered fermions along a line of constant physics defined by a pion mass of about 220 MeV and a kaon mass of 500 MeV. The lattices had temporal extents N τ =4, 6 and 8 and aspect ratios of N s /N τ ≥4. At least up to a temperature of 140 MeV the pseudo-scalar screening mass remains almost equal to the corresponding zero temperature pseudo-scalar (pole) mass. At temperatures around 3T c (T c being the transition temperature) the continuum extrapolated pseudo-scalar screening mass approaches very close to the free continuum result of 2πT from below. On the other hand, at high temperatures the vector screening mass turns out to be larger than the free continuum value of 2πT. The pseudo-scalar and the vector screening masses do not become degenerate even for a temperature as high as 4T c . Using these mesonic spatial correlation functions we have also investigated the restoration of chiral symmetry and the effective restoration of the axial symmetry. We have found that the vector and the axial-vector screening correlators become degenerate, indicating chiral symmetry restoration, at a temperature which is consistent with the QCD transition temperature obtained in previous studies. On the other hand, the pseudo-scalar and the scalar screening correlators become degenerate only at temperatures larger than 1.3T c , indicating that the effective restoration of the axial symmetry takes place at a temperature larger than the QCD transition temperature. 相似文献
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We present a self-consistent determination of the screening mass for chromomagnetic fields in QCD within the framework of dimensional reduction. The three-dimensional Chern-Simons density is used as a mass term for a self-consistent perturbative calculation that yields a value of m approximately 1.604(g(2)N/2pi)T for the magnetic screening mass. 相似文献
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Based on random matrix theory and reduced BS equation, it is found that the regular motion of cc system can be expected at a small value of color screening mass but the chaotic motion at a large one. It is shown that the level mixing due to color screening serves as a new mechanism resulting in J/Ø suppression. Moreover, this kind of suppression can occur before the color screening mass reaches its critical value for J/Ø dissociation. In addition, it is. implied that a strong J/Ø suppression is possible in the absence of dissociation of J/Ø. 相似文献