Simulation of electromagnetic shower formation in a Germanium crystal

Abstract

When high-energy electrons penetrate crystalline matter, the successive processes of photon emission and pair production form an electromagnetic shower. If the incident electrons are directed along the crystal axis, the cross section for photon emission is drastically enhanced because electrons in ‘channeling’ states feel a strong electric field continuously. Experiments designed to detect this effect were performed at CERN. The results showed an anomalous peak in the energy loss spectrum of the emerging electrons. In this paper, we report results of a Monte-Carlo simulation of shower formation in a Germanium crystal. Our results agree with the experimental data more quantitatively than previous simulations. We simulated a shower formation by incident photons as well.     

Dielectric Spectra and d-bands Structure of Germanium,Tin, and Lead Tellurides

Russian Physics Journal - The known experimental absorption spectra were used to calculate the dielectric spectra of GeTe, SnTe, and PbTe crystals in the region of electron transitions from the...     

两种蒙药无机锗和有机锗的测定

本文采用方波极谱法 ,在 p H=1.30的 H2 SO4和 3,4 -二羟基苯甲醛 (DHB)的底液中 ,获得无机锗的方波极谱波 ,峰电位为 Ep=- 0 .5 2 V,在浓度 2 .8× 10 -5— 2 .8× 10 -3 mol/ L内与峰电流呈线性关系 ,方法简单。本法用于蒙药中无机锗和有机锗的测量 ,测定结果满意     

Electron-phonon Coupling in Gallium-Doped Germanium

The electronic structure, lattice dynamics, and electron-phonon coupling of gallium-doped germanium are inves- tigated using ab initio supercell methods. Our results indicate the superconducting transition in gallium-doped germanium can be explained within a standard phonon mediated mechanism. The contribution of acoustic modes to the coupling constant A almost entirely comes from Ga related modes, and - 25% to λ. The calculated coupling constant is 0.35 and the corresponding transition temperature is 0.44 K for the gallium-doped germanium with 6.25% gallium content using Coulomb pseudopotential μ^＊ = 0.1, in agreement well with the experimental data.     

Dislocation Generation in Dislocation-Free Germanium

A dislocation structure is studied in germanium single crystals grown in a regime of minimum temperature gradients at the crystallization front and low supercooling. The investigations show that the distortion of the flat crystallization front arising during crystal droplet detachment in the completion growth stage results in the dislocation generation in the lower parts of dislocation-free single crystals. The dislocations are generated at the phase boundary and propagate in the thermoplasticity zone. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 21–24, May, 2005.     

极端条件下Ge_3N_4的弹性性能、电子性质和相稳定性

采用密度泛函理论框架下的平面波方法结合准谐近似,研究了Ge3N4的β相、w相和γ相在高温高压条件下的力学稳定性、相变点、电子结构和弹性性质。结果表明:γ相的抗剪切能力最强、刚度最大、属于超硬材料,β相具有最小的体弹模量、杨氏模量和G/B值、因此韧性和延性最好;w相和β相都属于延性相;而γ相则呈现出脆性,在30GPa后转变为延性材料。3种相都属于半导体,成键主要来自于N-2p轨道和Ge-4s、Ge-4p轨道的杂化;它们的结构能保持稳定是源于强烈的共价键;β相、w相和γ相分别属于Γ-A型、Γ-N型间接带隙和直接带隙半导体。研究发现,β→w相变对压强非常敏感,可以认为该相变是因压强的改变而引起的;w→γ相变伴随着晶胞体积的塌缩;同时,还成功地得到了β→w→γ相变的相界。     

锗双曲面的加工

锗是常用的红外光学材料。随着科学技术的不断发展,对锗零件的技术要求越来越高,其加工难度也越来越大。本文介绍一些加工锗双曲面的经验。     

TheK-Fluorescence Yield of Germanium

TheK-Fluorescence Yield _k of Germanium has been measured using the coincidence method and investigating the decay of⁷⁴As. The branching ratios of this decay had to be measured and all relevant determining values, as detection efficiencies, absorption coefficients etc. The experimental results areP _{K K} = 0.494±0.012 and _K= 0.561±0.015 usingP _K= 0.881±0.003. For the branching ratios of the decay of⁷⁴As we obtainedEC ₂ (1.204) 0.88±0.06%EC ₁ (0.596) 32.8±0.8 % ₁ ⁺ (0.596) 24.7±0.8 %EC _{1 1} ⁺ =1.332±0.046.Additionally the half-lifeT _1/2=(17.76±0.03) d has been measured.     

原子吸收光谱法测定有机锗（Ge─132）中的锗及其杂质

火焰原子吸收法测定有机锗（Ｇｅ．１３２）①中的锗，线性浓度范围为０－１．２５ｍｇ／ｍＬ，方法精度为１．２％，相对标准偏差＜２％，平均回收率为９９．５％。杂质Ｐｂ和Ａｓ用塞曼石墨炉原子吸收测定，Ｐｂ用（ＮＨ_４）_２ＨＰＯ_４＋Ｍｇ作改进剂，Ａｓ用Ｐｄ作改进剂，特征质量分别为８．２ｐｇ和８ｐｇ，相对标准偏差分别为２．１％和２．２％，并讨论了有关机理问题。     

分光光度法测定饮料食品中痕量有机锗和无机锗的研究

本文研究了在溴化十六烷基三甲基铵（ＣＴＭＡＢ）抗坏血酸（Ｖｃ）存在下，苯基荧光酮（Ｐｆ）光度法测定痕量锗的最佳实验条件及配合物的组成，从而建立了测定痕是锗的新方法，其方法的灵敏度ε＝１．０３４×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１锗含量在０－１６．８μｇ／２５ｍＬ范围内符合比耳定律，稳定性好，操作简便，快速。应用本法测定了矿泉水，茉莉花茶，大蒜中有机锗和无机锗的含量，回收率在９１．６％－１０３．５     

分光光度法测定鱼翅中锗

本文用分光光度法测定鱼翅中的总锗量。结果表明 ,鱼翅中的总锗含量为 18.2 5— 2 2 .75 μg·g-1;回收率为 85 .8%— 93.2 %。     

Theory of donor-bound multi-exciton complexes in Germanium

We report calculations of ground and excited state energies for multi- exciton complexes bound to phosphorus, arsenic, and bismuth donors in germanium. Band structure effects are included in a self consistent density functional calculation. Theoretical recombination spectra derived from our results agree very well with existing data. The results imply the existence of a kinetic bottleneck to the growth of large complexes.     

分光光度法测定食品中的锗

在浓度为 1 .2 mol/ L的 HCl介质中 ,苯芴酮与锗反应生成橙红色络合物 ,λmax=5 30 nm,ε=3× 1 0 4 L· mol- 1 · cm- 1 ,锗含量在 0 .5 - 5 0μg/ 5 0 m L范围内符合比尔定律 ,本方法用于食品中锗的测定 ,结果令人满意。     

锗的光度分析进展

锗是一种重要的稀有元素，同时也是半导体工业的重要原料。近年来，锗及其化合物的生理作用也日益引起人们的重视。本文对１９８８年以来国内外锗的光度分析（包括荧光光度法和化学发光法）进展进行了综述。引用参考文献８９篇。     

Indirekte Band-Band-Stoßrekombination in Germanium

Photoemission from Ge, caused by carrier injection via ap-n-junction was observed at a wavelength about 1 μm at room temperature. The dependence on energy, temperature and carrier density shows, that there appears a high energy tail of a radiative band to band recombination, which cannot be the tail of the usual radiative recombination in Ge. The intensity of the photoemission is proportional ton ² p ². The experimental results are explained as follows: Via indirect band to band Auger-recombination a hole is brought into the split-off band. In this band, the hole reaches thermal equilibrium with the lattice. While it remains in this band, it is able to recombine radiatively with electrons of the conduction band.     

强磁场下锗电阻温度传感器的磁致电阻效应研究

以锗温度传感器GR-1400-AA为研究对象,研究了其在0～16 T磁场下、2～100K温区内的磁致电阻效应。结果表明:在2～20K温区,GR-1400-AA磁效应随温度的升高急剧降低,且场强越高磁效应的变化率越大;在20～100K温区,磁效应随温度的升高趋于平缓;GR-1400-AA磁效应随场强的升高而升高,且温度越低,磁效应的变化率越高,2.1K、16T处的磁效应为2120.3%;GR-1400-AA由磁阻引起的测量温差随温度的升高而升高,随场强的增大而增大,且全为负温差,在6K、2T处和16T、100K处的测量温差分别为-0.24K、-60.4K。不推荐应用在磁场环境下。     

Quantitative piezospectroscopy of group V impurities in Germanium

The deformation potential constant, ξ_u, of the lowest conduction band of germanium is found to be 16.4 ± 0.2 eV from the splitting of the 2p₀ line of arsenic impurity under uniaxial stress. The same value is found for Ξ_u of the lower ground state.     

分光光度法测定银杏中有机锗

本文用分光光度法测定银杏中的有机锗含量。结果表明，灰化法操作简单、准确，方法回收率为99．24％－100．26％，结果满意。