Dielectronic Recombination of Sn^10＋ Ions and Related Satellite Spectra

Based on the multi-configuration Dirac-Fock method, theoretical calculations are carried out for the dielectronic recombination （DR） rate coefficients and the collision excitation rate coefficients of Sn^10＋ ions. It is found that the total DR rate coefficient has its maximum value between 10eV and 100eV and is greater than either the radiative recombination or three-body recombination rate coefficients （the number of free electrons per unit is 10^21 cm^3） for the ease of Te 〉 1 eV. Therefore, DR can strongly influence the ionization balance of laser produced multi-charged tin ions. The related dieleetronie satellite cannot be ignored at low temperature Te 〈 5 eV.     

Density and Symmetric Potential Dependences of Isoscaling Behaviour in the Lattice Gas Model

Isoscaling behaviour of the statistical emission fragments from the equilibrated sources with Z=30 and N=30, 33, 36 and 39 is investigated in the framework of the isospin-dependent lattice gas model. The dependences of isoscaling parameters α on source isospin asymmetry, temperature andfreeze-out density are studied, and the `symmetry energy' is deduced from isoscaling parameters. The results show that symmetry energy C_sym is insensitive to the change of temperature but follows the power-law dependence on the freeze-out density ρ. The effect of strength of asymmetry of nucleon--nucleon interaction potential on the density dependence of the symmetry energy is discussed.     

Wavelet Cross-Spectrum Analysis of Multi-Scale Disturbance Instability and Transition on Sharp Cone Hypersonic Boundary Layer

Experimental measurement of hypersonic boundary layer stability and transition on a sharp cone with a half angle of 5° is carried out at free-coming stream Mach number 6 in a hypersonic wind tunnel. Mean andfluctuation surface-thermal-flux characteristics of the hypersonic boundary layer flow are measured by Pt-thin-film thermocouple temperature sensors installed at 28 stations on the cone surface along longitudinal direction. At hypersonic speeds, the dominant flow instabilities demonstrate that the growth rate of the second mode tends to exceed that of the low-frequency mode. Wavelet-based cross-spectrum technique is introduced to obtain the multi-scale cross-spectral characteristics of the fluctuating signals in thefrequency range of the second mode. Nonlinear interactions both of the second mode disturbance and the first mode disturbance are demonstrated to be dominant instabilities in the initial stage of laminar-turbulence transition for hypersonic shear flow.     

Permutation Matrix Method for Dense Coding Using GHZ States

We present a new method called the permutation matrix method to perform dense coding using Greenberger--Horne--Zeilinger (GHZ) states. We show that this method makes the study of dense coding systematically and regularly. It also has high potential to be realized physically.     

Comparison of Laser Performances of 5at.% Yb:Gd2xY2(1-x)SiO5 Crystals between Different Cutting Directions

We investigate the laser actions of 5at.% Yb:Gd_2xY_2(1-x)SiO₅ (Yb:GYSO; x=0.1) crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of the sample plays an astonished role in the laser operation. The sample cut vertically to the growth axis possesses the favourable lasing characteristics. Its output power reaches 3.13W at 1060nm with a slope efficiency of 44.68% when the absorbed pump power is 8.9,W. In contrast, the sample cut parallel reaches only 1.65W at 1044nm with a slope efficiency of 33.76% with absorbed pump power of 7.99W. The absorption and emission spectra of the two samples are examined and the merit factor M is calculated. Our analysis is in agreement well with the experimental results. The wavelength tuning range of the superior sample covers from 1013.68nm to 1084.82nm.     

Large Magnetoresistance Based on Double Spin Filter Tunnel Barriers

We propose and theoretically analyse a double magnetic tunnel device that takes advantages of the spin filter effect. Two magnetic tunnel barriers are formed by different spin filters which have different barrier heights. The magnetoresistance of the device is low （high） when the magnetic moments of the two spin filters are parallel （antiparallel）. We present a theoretical calculation of the magnetoresistance based on electric tunnel effect. In addition, the effect of the difference barrier heights and exchange splitting energies between the two spin filters are also analysed in detail. The numerical results show that the spin filter in this configuration gives a magnetoresistance larger than that with standard magnetic tunnel junctions.     

Off-Shell Effect of Quarks in Bs→γe+e-

We evaluate the rare decays B_s→γe⁺e^- in the standard model, considering the off-shell effect of quarks in B_s meson as well as some contributions neglected in previous works. It is found that the quarks off-shell are large. With the predicted branching ratios at order of 10^-8, it is expected that the radiative dileptonic decays will be detected in the LHC-b experiments.     

掺杂对二硼化镁超导体上临界磁场的影响

采用二带Ginzburg-Landau(GL)理论模型,考虑到能带有效质量的各向异性,讨论了MgB2超导体的上临界磁场对角度、温度和相干长度的依赖关系.结果表明,替代杂质越多,上临界磁场越强,这与实验结果符合.     

微环耦合谐振光波导中的色散控制模型与数值仿真

本文利用传输矩阵法得到了微环耦合谐振光波导的色散关系,讨论了耦合损耗、传输损耗及耦合系数对微环耦合谐振光波导色散的影响,改变耦合损耗、传输损耗及耦合系数可控制其色散曲线的形状、位置、以及带宽,色散曲线的变化及控制对微环耦合谐振光波导在滤波、光信号延迟及缓存等方面的应用有重要意义. 关键词： 光波导 微环光波导 传输矩阵法     

射频辅助N掺杂ZnO薄膜的生长及其光电特性

在MOCVD设备中采用改进的射频辅助生长装置,通过裂解N2及N-Al共掺杂的方法进行ZnO的p型掺杂研究。通过二次离子质谱(SIMS)、X射线衍射(XRD)、原子力显微镜(AFM)、光致发光(PL)谱等方法分析了薄膜中N杂质的浓度,以及射频功率与晶体质量、表面形貌以及光学特性之间的关系,并与Al掺杂和N掺杂的ZnO薄膜进行对比。实验结果表明,N掺杂的浓度高达1020cm-3;N-Al共掺杂极大地增加了ZnO的成核速率,其主要原因是N离化所起的作用;N-Al共掺的ZnO薄膜显示出p型性质,而N掺杂的ZnO薄膜由于N原子处于非激活状态而呈现高阻,这说明N-Al共掺杂对ZnO中N原子的活化起到一定作用。