法拉第旋转镜用于补偿单光子偏振漂移的实验研究

研究了法拉第旋转镜用于补偿单模光纤中1 550 nm单光子传输的偏振漂移特性.比较了不同平均光子数下经由不同长度单模光纤传输后单光子偏振漂移的差异,以及使用法拉第旋转镜的偏振漂移抑制比.实验结果表明,在50 km光纤50 kcps光子计数（光强）下偏振漂移改善最优,偏振漂移抑制比达25.3.     

�߹��������ƽ��ſؽ���ŵ����ԺͲ����о�

用线圈电流控制非平衡磁场,用汤森放电击穿形成深度自触发放电,用磁阱捕获放电形成的二次电子和导致漂移电流,形成了高功率非平衡磁控溅射放电。采用偏压为-100V相对磁控靶放置的圆形平面电极收集饱和离子电流;在距离磁控靶14cm的位置由Langmuir探针测量浮置电位;示波器测量磁控靶的脉冲电压、电流、浮置电位和饱和离子电流信号。装置的放电脉冲功率达到0.9MW,脉冲频率最大值为40Hz左右,空间电荷限制条件是控制电子电流和离子电流的主要机制。     

半绝缘GaAs的欧姆接触电极材料Ag/Co掺杂的非晶碳膜制备与检测

稳定的欧姆接触对半导体器件的正常工作起到至关重要的作用.目前市场上主要采用金/金锗镍合金作为n型GaAs的电极材料,工艺复杂,成本高昂.本文研究了一种新型的、廉价的适用于半绝缘GaAs的欧姆接触电极材料Ag/Co掺杂的非晶碳膜及其制备过程,以便于读者对半导体器件的制备工艺和流程有所了解.     

北京谱仪III上利用神经网络方法进行粒子鉴别的研究

本文描述了一种多层感知器的神经网络系统在BESIII粒子鉴别技术中的应用。网络按照子探测器分别进行训练, 输出结果可以作为后续网络的输入或者可以为似然函数方法构建概率密度函数。蒙特卡罗模拟样本的检验结果表明, 利用神经网络方法可以在BESIII上获得较好的粒子鉴别效果。     

ICP-MS测定动物肝脏中铅、镉和砷

利用电感耦合等离子体-质谱法(ICP-MS)同时测定动物肝脏中铅、镉、砷3种元素.样品经聚四氟乙烯高压消化罐消解后,以锗、铟、铋作为内标物质,补偿基体效应,直接用ICP-MS同时测定这3种元素,结果令人满意.该法线性范围宽,分析速度快,准确度和精密度均符合分析测试要求.     

采用罗戈夫斯基线圈诊断径向束流

 罗戈夫斯基线圈具有结构简单、高频特性好等特点而被广泛应用于脉冲电流测量。提出了用两个自积分式罗戈夫斯基线圈诊断径向束流的方法,在此基础上设计了两个用于径向束流诊断的自积分式罗戈夫斯基线圈,对其进行了标定。当标准电流的上升沿为30 ns时,罗氏线圈响应时间约为10 ns;整个系统的测量误差约为4.7%。从标定结果来看,该系统的频率响应特性和测量精度能够满足ns级束流诊断的要求,该方法可以用于径向结构高功率微波器件的束流强度测量。     

（Na0.52K0.44Li0.04）Nb0.9-xSbxTa0.1O3 Lead-Free Piezoelectric Ceramics with High Performance and High Curie Temperature

（Na0.52K0.44Li0.04）Nb0.9-x Sbx Ta0.1O3 lead-free piezoelectric ceramics are prepared by a solid-state reaction method. With increasing Sb content, the transition temperature from orthorhombic to tetragonal polymorphic phase decreased. A composition （Na0.52K0.44Li0.04）Nb0.863Sb0.037Ta0.1O3 is found to possess excellent piezo- electric and electromechanical performances （d33 = 306pC/N, kp =48%, and kt=50%）, and high Curie temperature （Tc = 320 ℃）. These results indicate that （Na0.52K0.44Li0.04）Nb0.863Sb0.037 Ta0.1O3 is a promising lead-free piezoceramics replacement for lead zirconate titanate.     

Dependence of Crystal Quality and β Value on Synthesis Temperature in Growing Gem Diamond Crystals

High quality Ib gem diamond single crystals were synthesized in cubic anvil high-pressure apparatus （SPD- 6 × 1200） under 5.4GPa and 1230℃-1280℃. The （100） face of seed crystal was used as growth face, and Ni70Mn25Co5 alloy was used as solvent/catalyst. The dependence of crystal quality andβ value （the ratio of height to diameter of diamond crystal） on synthesis temperature was studied. When the synthesis temperature is between 1230℃ and 1280℃, theβ value of the synthetic high-quality gem diamond crystals is between 0.4 and 0.6. The results show that when theβ value is between 0.4 and O. 45, the synthetic diamonds are sheet-shape crystals; however, when theβ value is between 0.45 and 0.6, the synthetic diamonds are tower-shape crystals. In addition, when theβ value is less than 0.4, skeleton crystals will appear. When theβ value is more than 0.6, most of the synthetic diamond crystals are inferior crystals.     

Effects of Li Substitution and Sintering Temperature on Properties of Bi0.5（Na,K）0.5TiO3 Lead-Free Piezoelectric Ceramics

Bi0.5 （Na0.72K0.28- x Lix ）0.5 TiO3 （BNKLT- 100x） lead-free piezoelectric ceramics are synthesized by conventional solid state sintering techniques. The dielectric and piezoelectric properties of the BNKLT-100x ceramics as a function of Li content are systematically investigated. It is found that not only Li content but also the sintering temperature has a strong effect on the piezoelectric properties of BNKLT. The piezoelectric constant d33 Of BNKLT varies from 120 to 252pC/N in the Li content range from 0.03 to 0.16. In the sintering temperature range from 1080 to 1130℃, the d33 value of BNKLT-6 changes from 200pC/N to 252pC/N. The BNKLT-6 sample sintered at 1100℃ has the highest piezoelectric constant d33 of 252pC/N, with the electromechanical coupling factors kp of 0.32 and kt of 0.44.     

Demonstration of a 4H SiC Betavoltaic Nuclear Battery Based on Schottky Barrier Diode

A 4H SiC betavoltaic nuclear battery is demonstrated. A Schottky barrier diode is utilized for carrier separation. Under illumination of Ni-63 source with an apparent activity of 4mCi/cm^2, an open circuit voltage of 0.49 V and a short circuit current density of 29.44nA/cm^2 are measured. A power conversion efficiency of 1.2% is obtained. The performance of the device is limited by low shunt resistance, backscattering and attenuation of electron energy in air and Schottky electrode. It is expected to be significantly improved by optimizing the design and processing technology of the device.