利用宇宙线对BESⅢ量能器CsⅠ（Tl）晶体探测器单元的测量

利用宇宙射线进行探测器模型的性能测试是高能物理普遍采用的方法，其中最重要的步骤之一就是确定宇宙线入射的准确位置和径迹．多数采用丝室探测器来进行宇宙线的精确定位，需要很高的造价和复杂的电子学系统．本文介绍一种简单的定位方法，采用塑料闪烁体条加波移剂光纤编码读出的方式，可以实现精度为1cm的定位．据此建立了一套实验装置，对BESⅢ电磁量能器CsⅠ（Tl）晶体探测器单元的光输出强度和不均匀性进行了测量．     

氢离子与里德伯原子碰撞中的电荷转移过程

应用双中心原子轨道强耦合方法研究了H⁺与里德伯态原子Li（5d）碰撞的电荷转移过程,计算了电子转移到氢原子各个n,l壳层（这里n为主量子数,l为角量子数）的态选择截面.结果发现,电荷转移的末态主要分布在与初态电子能量5d接近的n=4—7能级,该分布随碰撞能量的变化不大;但俘获末态的l分布对入射离子能量很敏感：在1 keV左右的低能时主要分布在高l的末态,随着碰撞能量增加峰值逐渐向低l方向移动,并在l= 关键词： 电子俘获过程 双中心原子轨道强耦合方法 态选择截面     

轴对称流场干涉条纹折射率的模拟计算

提出一种获取流场干涉条纹折射率分布的新方法。该方法首先采用不等间隔的环带分割轴对称流场,使折射率变化大的地方获得的数据点密,然后通过对Abel变换进行离散数值计算来获取流场的折射率分布。通过模拟轴对称流场的实时全息干涉条纹证明了该方法不仅简单易行,而且所获取的折射率分布精度高。     

Tribological Behavior of Multiply-Alkylated Cyclopentanes (MACs)-Cu Nanoparticles Composite Thin Film

Multiply-alkylated cyclopentanes (MACs) composite thin films containing Cu nanoparticles are fabricated on the octadecyltrichlorosilane (OTS)-modified substrate by a spin-coating technique. The thickness, wetting behavior, and nanoscale morphologies of the films are characterized by means of ellipsometry, contact angle measurement, and atomic force microscope (AFM). The friction and wear behaviors of the thin films sliding against Si₃N₄ ball are examined on a UMT-2MT tribometer in a ball-on-disk contact mode. The worn surfaces of the OTS-MAC-Cu composite film and the counterpart Si₃N₄ balls are investigated with a scanning electron microscope. Water contact angle on OTS-MAC-Cu composite film is higher than that of OTS-MAC film. OTS-MAC-Cu composite film exhibits higher load-carrying capacity and better friction reduction and antiwear behavior as compared with OTS-MAC film. This may be attributed to the load-carrying and self-repairing property of the Cu nanoparticles in the composite film and the formation of a transfer layer composed of OTS, MAC, and Cu on the rubbing surface of the counterpart ball.     

Anomalous Hall effect of heavy holes in III-V semiconductor quantum wells

The anomalous Hall effect of heavy holes in semiconductor quantum wells is studied in the intrinsic transport regime, where the Berry curvature governs the Hall current properties. Based on the first--order perturbation of wave function the expression of the Hall conductivity the same as that from the semiclassical equation of motion of the Bloch particles is derived. The dependence of Hall conductivity on the system parameters is shown. The amplitude of Hall conductivity is found to be balanced by a competition between the Zeeman splitting and the spin--orbit splitting.     

Luminescence of a GaN grain with a nonpolar and semipolar plane in relation to microstructural characterization

We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask.Transmission electron microscopy,scanning electron microscopy,and Raman spectroscopy are used to reveal the effect of SiN on the overgrown a-plane GaN growth.The SiN layer effectively terminates the propagation of the threading dislocation and basal plane stacking faults during a-plane GaN regrowth through the interlayer,resulting in the window region shrinking from a rectangle to a "black hole".Furthermore,strong yellow luminescence(YL) in the nonpolar plane and very weak YL in the semipolar plane on the GaN grain is revealed by cathodoluminescence,suggesting that C-involved defects are responsible for the YL.     

热氧化法制备ZnO纳米晶体、纳米线

以高纯Zn块为源材料,通过热氧化法制备了纳米ZnO薄膜。在950℃的温度和一定的压力条件下,通过改变生长时间,分别制备了ZnO纳米晶体、纳米纤维和纳米线。应用扫描电镜观察发现,在恒温生长条件下,纳米ZnO具有定向生长的趋势。随生长时间的延长,纳米晶体定向生长为纳米纤维,最后生长为超长的纳米线。     

基于Fibonacci序列准周期结构的小角度低通空间滤波器

利用常规材料构造了Fibonacci序列准周期结构,运用传输矩阵法研究了该结构的空间传输特性,并基于该结构优良的空间传输特性设计了小角度低通空间滤波器.数值模拟结果表明,该小角度空间滤波器的角域带宽可通过改变序列的结构类型和序列数来调谐,其调谐规律为:随着Fibonacci序列F(m,1)中m值的增加,对应空间滤波器的角域带宽减小;随着序列数的增大,对应角域带宽也减小.在调谐的基础上,还可通过改变构成准周期结构的介质折射率参量来精确调节其角域带宽.相比于基于超材料的小角度空间滤波器而言,基于Fibonacci序列的小角度空间滤波器制备更简单,且有望应用于新一代的高功率激光系统中.     

火焰原子吸收光谱法测定钴-镍合金镀层中的钴和镍

利用原子吸收光谱法研究了在氨基磺酸钴-镍镀液中，赫尔槽试片上不同电流密度区合金镀层中钴、镍的含量。实验表明，该方法简便，快捷，结果准确，精密度高。相对标准偏差（RSD）为0.30%-0.62%，加标回收率为97.0%-104.0%。     

双硬度靶对球形弹丸的防护性能

以钢/铝双硬度爆炸焊接复合靶为研究对象,采用系列弹道实验和数值模拟方法,研究了其在球形弹丸垂直侵彻作用下的抗侵彻性能。侵彻实验利用直径为14.5mm的滑膛枪发射直径为6mm的钢质球形弹丸;采用LS-DYNA3D非线性有限元程序和有限元-光滑粒子流体动力学(FE-SPH)耦合法,进行数值模拟。基于实验和数值模拟结果,分析了不同靶板的毁伤机理和破坏模式,以及靶板厚度、强度等因素对复合靶抗侵彻性能的影响。结果表明:在球形弹丸的垂直侵彻作用下,钢面板发生剪切冲塞破坏,铝背板发生延性扩孔破坏;对于双层靶而言,钢面板与铝背板的厚度比约为2/3时,复合靶的抗侵彻性能最差;数值计算结果与实验结果吻合良好,表明FE-SPH耦合算法可较好地预测双层复合靶板的抗侵彻性能。