A wide dynamic range laser rangefinder with cm-level resolution based on AGC amplifier structure

A pulsed time-of-flight (TOF) laser rangefinder with a pulsed laser diode and an avalanche photo diode (APD) receiver is constructed and tested. Trigged by an avalanche transistor, the laser diode can emit a periodic pulse with rise time of ～2 ns. A new structure with auto gain control (AGC) circuits both in the pre-amplifier and the post-amplifier is presented. Through this technology, not only the dynamic range of the receiver is extended, but also the walk error of timing discriminators is reduced. Large measurement range from 5 m to 500 m is achieved without any cooperative target. The single-shot precision is 3 cm for the weakest signal. Compared with previous laser rangefinders, the complexity of this system is greatly simplified.     

Preparation and characterization of Cobalt Sulfophthalocyanine/TiO2/fly-ash cenospheres photocatalyst and study on degradation activity under visible light

Cobalt Sulfophthalocyanine (CoSPc) sensitized TiO₂ sol samples were prepared through a Sol-Gel method using Cobalt Sulfophthalocyanine as a sensitizer. Loading and modified floating photocatalyst was prepared by hydrothermal method using fly-ash cenospheres as a carrier. The properties of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance spectrum (DRS). Photocatalytic activity was studied by degrading wastewater of methylene blue under visible light. The results indicate that the fly-ash cenospheres are covered by modified TiO₂ film which composed of the anatase, brookite and rutile misch crystal phase. CoSPc/TiO₂/fly-ash cenospheres samples have good catalytic activity under visible light, and have strong absorbency during 600-700 nm. The sensitization of CoSPc can enhance visible light catalytic activity of TiO₂/fly-ash cenospheres. The degradation rate of methylene blue reaches 73.36% in 180 min under the visible light illumination. But too much CoSPc can decrease its catalytic activity.     

合肥国家同步辐射光源软X射线束空间相干性实验研究

本文从实验角度对合肥国家同步辐射实验室软X射线束的空间相干性进行了研究.利用放置在物面上的高分辨正性光刻胶,记录了中心波长为3.2nm的波带片和针孔直径为30μm组合的光场分布(光斑),获得相应条件下的爱里斑及空间相干直径实验数据;完成了一个双缝干涉实验.所得的这些结果与理论计算相一致.     

短寿命核转轮传送装置

在中国原子能科学研究院的串列式静电加速器上建立了传送短寿命核的转轮装置,可用于鉴别和研究寿命短至几秒的核素．该装置已用于新的缺中子核素９０Ｒｕ的鉴别及其半衰期和衰变γ的测量． A wheel device for transporting short-lived nuclei has been constructed at the HI-13 tandem accelerator of CIAE. The device can be used in the identification and investigation of nuclides with life-times as short as a few seconds. With the aid of this device a new nutron-deficient nuclide 90Ru has been identified. Its half-life and decay γ-rays have been measured.     

Mo/Si aperiodic multilayer broadband reflective mirror for 12.5-28.5-nm wavelength range

Aperiodic molybdenum/silicon (Mo/Si) multilayer designed as a broadband reflective mirror with mean reflectivity of 10% over a wide wavelength range of 12.5-28.5 nm at incidence angle of 5° is developed using a numerical optimized method. The multilayer is prepared using direct current magnetron sputtering technology. The reflectivity is measured using synchrotron radiation. The measured mean reflectivity is 7.0% in the design wavelength range of 12.5-28.5 nm. This multilayer broadband reflective mirror can be used in extreme ultraviolet measurements and will greatly simplify the experimental arrangements.     

Fermi能区核－核碰撞的平衡前中子发射

利用ＢＵＵ模型模拟核－核碰撞３６Ａｒ＋１０８Ａｇ（３５Ｍｅｖ／ｕ）、１４Ｎ＋１０８Ａｇ（３５ＭｅＶ／ｕ）中的平衡前中子发射．模拟结果与唯象的运动源拟合给出的中等速度源成份相吻合．这说明中等速度源成份产生于核－核碰撞的早期，对应平衡前发射．并从级联碰撞的角度定量地研究了平衡前发射的持续时间     

表面喷砂对有机玻璃沿面闪络性能影响

绝缘子表面粗糙处理是提升其沿面闪络性能的重要途径,表面粗糙化处理方式不当,极易带来表面结构不均匀,难以获得稳定耐压性能的绝缘材料。为提升绝缘子表面粗糙处理的均匀性,本文利用表面喷砂技术对圆柱形有机玻璃（PMMA）绝缘子进行了粗糙化处理研究,以球形二氧化硅（SiO₂）颗粒为工作介质,研究了不同喷砂粒径、氢氟酸后处理等因素对绝缘材料表面形貌和组分的影响,并利用短脉冲高压测试平台对喷砂处理前后有机玻璃绝缘子样品进行了真空沿面闪络性能测试。研究结果表明,喷砂处理在有机玻璃表面形成了较为均匀的凹坑,HF酸能够有效去除表面残留的SiO₂颗粒,具有表面喷砂粗糙结构的绝缘子沿面闪络电压得到了稳定提升,相较于未处理的绝缘子闪络电压提升了约80%。     

3cm接收前端的小型化设计

介绍了3 cm低噪声接收前端的设计方法及为使其小型化应用使用了芯片GaAS MMIC混频器,并使用MWO软件对低噪声放大器电路进行了仿真。仿真数据和实测结果都表明,所设计的放大器具有较低的噪声和带内起伏,接收前端具有较高的镜像抑制度及良好的带外抑制。     

The factors of spontaneous parametric down conversion process in BiB3O6 crystal with a broadband pump

We investigate the spontaneous parametric down-conversion (SPDC) process in biaxial nonlinear crystal BiB₃O₆ (BIBO) with a broadband pump. Under the type I and type II phase-matching conditions, we numerically calculate the influencing factors on SPDC process in BIBO crystal, such as temporal and spatial walk-off, the acceptance angles, and spectral acceptance bandwidth. Comparing the two types of phase-matching, we could conclude that the type II phase-matching in BIBO crystal is better for the SPDC because of zero dispersion and bigger acceptance parameters. These results can be used to construct a system to generate ultra-fast entangled photon pairs.