HENDL1.1/MG数据库和VisualBUS1．0程序的临界基准计算与分析

使用自主开发的一维输运／燃耗／可视化计算程序系统VisualBUS1．0和HENDL1．1／MG数据库,对^233U,^235U和^239Pu的热溶液临界球基准实验和^237Np,^241Am和^244Cm的金属快裂变临界球问题进行校核。和国际上广泛使用的各种程序和数据库的模拟计算结果以及相关实验结果进行综合对比和分析,初步验证了HENDL1．1／MG中裂变核素核数据的可靠性和应用性,同时也进一步证明了VisualBUS1.0程序的正确性。The evaluated critical safety benchmark experiments including some major elements of fission materials, such as ^233U, ^235U, ^239pu and ^237Np, ^241Am, ^244Cm, were simulated using the home-developed one-dimensionaltrasportation/burnup/optimization code system VisualBUS1.0 and HENDL1.1/MG, a multi-group working library of fusion-fission Hybrid Evaluated Nuclear Data Library, by FDS team. By the comparison with the measured resuits and the calculated values given in the International Handbook of Evaluated Criticality Safety Benchmark Experiments, HENDL1.1/MG data library and VisualBUS1.0 code are validated and qualified to be reliable.     

High-Tc planar SQUID gradiometer for eddy current non-destructive evaluation

This paper reports the fabrication and test of a high-Tc SQUID planar gradiometer which is patterned from YBCO thin film deposited on a SrTiO3 bicrystal substrate. The measurement of noise spectrum at 77K shows that the white noise at 200 Hz is about 1×10^-4 φ0/√Hz. The minimal magnetic gradient is measured and the results suggest that the minimal magnetic gradient is 94 pT/m. The planar gradiometer is used in non-destructive evaluation （NDE） experiments to detect the artifacts in conducting aluminium plates by performing eddy current testing in an unshielded environment. The effect of the exciting coil dimension on the NDE results is investigated. By mapping out the induced field distribution, flaws about 10mm below the plate surface can be clearly identified.     

Charge coupled devices （CCD） photometry and long-term optical variability of gamma-ray-loud BL Lacertae object Mkn 421

Evidence for the long-term optical curve variability and colour behaviour of the BL Lac object Mkn 421 is presented. Our results show that the amplitude of the optical variations of Mkn 421 is only about {\Delta} B=4.7 magnitude in the B-band for its photometric history from 1899 to 2002. The results of optical photometric monitoring of the Mkn 421 from April 2000 to Jan 2002 are provided. During our observation, Mkn 421 shows significant rapid variations and exhibits short time variability of 2.42 hours in the B band. A strong correlation between the B-V colour index and the magnitude in the B band is found. Our charge coupled device (CCD) photometry of Mkn 421 shows that the measured results are in good agreement with the predicted optical variability period of about 23 years.     

Enhanced thermoelectric properties of p-type polycrystalline SnSe by regulating the anisotropic crystal growth and Sn vacancy

Thermoelectric selenides have attracted more and more attentions recently.Herein,p-type Sn Se polycrystalline bulk materials with good thermoelectric properties are presented.By using the SnSe_2 nanostructures synthesized via a wetchemistry route as the precursor,polycrystalline Sn Se bulk materials were successfully obtained by a combined heattreating process under reducing atmosphere and following spark plasma sintering procedure.As a reference,the Sn Se nanostructures synthesized via a wet-chemistry route were also fabricated into polycrystalline bulk materials through the same process.The thermoelectric properties of the Sn Se polycrystalline transformed from SnSe_2 nanostructures indicate that the increasing of heattreating temperature could effectively decrease the electrical resistivity,whereas the decrease in Seebeck coefficient is nearly invisible.As a result,the maximum power factor is enhanced from 5.06×10~(-4)W/m·K~2to 8.08×10~(-4)W/m·K~2at 612~?C.On the other hand,the reference sample,which was obtained by using Sn Se nanostructures as the precursor,displays very poor power factor of only 1.30×10~(-4)W/m·K~2at 537~?C.The x-ray diffraction(XRD),scanning electron microscope(SEM),x-ray fluorescence(XRF),and Hall effect characterizations suggest that the anisotropic crystal growth and existing Sn vacancy might be responsible for the enhanced electrical transport in the polycrystalline Sn Se prepared by using SnSe_2 precursor.On the other hand,the impact of heat-treating temperature on thermal conductivity is not obvious.Owing to the boosting of power factor,a high z T value of 1.07 at 612~?C is achieved.This study provides a new method to synthesize polycrystalline Sn Se and pave a way to improve the thermoelectric properties of polycrystalline bulk materials with similar layered structure.     

新型超导量子比特及量子物理问题的研究

近年来,超导量子计算的研究有了很大的进展.本文首先介绍了nSQUID新型超导量子比特的制备和研究进展,包括器件的平面多层膜制备工艺和量子相干性的研究.这类器件在量子态的传输速度和二维势系统的基础物理问题研究方面有着很大的优越性.其次,国际上新近发展的平面形式的transmon和Xmon超导量子比特具有更长的量子相干时间,在器件的设计和耦合方面也有相当的灵活性.本文介绍了我们和浙江大学与中国科学技术大学等单位合作逐步完善的这种形式的Xmon器件的制备工艺、制备出的多种耦合量子比特芯片,以及参与合作,在国际上首次完成的多达10个超导量子比特的量子态纠缠、线性方程组量子算法的实现和多体局域态等固体物理问题的量子模拟.最后介绍了基于这些超导量子比特器件开展的大量的量子物理、非线性物理和量子光学方面的研究,包括在Autler-Townes劈裂、电磁诱导透明、受激拉曼绝热通道、循环跃迁和关联激光等方面形成的一整套系统和独特的研究成果.     

低于阈值激光功率密度下Mg原子的非序列双电离

基于经典系综模型,研究了Mg原子在低于重碰撞阈值激光功率密度下的非序列双电离(NSDI)。当少周期量级线性偏振激光的功率密度为3.0×10~(13) W·cm~(-2)时,末态关联电子动量分布中的电子对主要分布在第一、第二和第四象限,第一象限中的电子对呈现了明显的关联行为。分析了重碰撞和双电离之间的延迟时间,发现不同的延迟时间对应着不同的电离过程,延迟时间对电子出射过程具有显著影响;延迟时间小于半个周期的NSDI事件,双电子倾向于反方向出射,而延迟时间大于半个周期的,存在双电子同方向出射的可能。     

高温超导量子干涉器件在磁性粒子标记免疫测定中的应用

具有超顺磁特性的Fe3O4纳米磁性粒子在外场中被极化时会产生沿极化方向的宏观磁矩,当撤销极化磁场后,利用高灵敏的高温超导量子干涉仪(SQUID)测量磁性粒子的磁弛豫行为.由于小尺度的磁性粒子磁性衰减很快,其行为遵循布朗弛豫;相较而言,通过生物待标记物连接的较大尺度磁性粒子或发生偶连的磁性团簇磁性衰减较慢,满足尼尔弛豫的条件.根据磁性颗粒的磁弛豫特性配合超导SQUID的低噪声实现对磁性粒子标记的微量生物待标记物的免疫检测.分别对平均尺寸为144nm的聚苯乙烯磁珠和406nm的二氧化硅磁珠的磁性衰减信号进行测量,得到了一些初步的实验结果.前者聚苯乙烯磁珠样品因磁珠尺寸太小,磁弛豫太快,未见明显的响应曲线;而后者的弛豫曲线遵循尼尔弛豫指数关系.结果表明粒子的有效弛豫依赖于磁性团簇的尺度.并且通过加大极化场,可以增强磁珠的尼尔弛豫信号,提高测量灵敏度。     

结合小波分析法与导数光声光谱技术测量弱光谱信号的实验研究

结合导数光声光谱技术与小波分析方法,精确测量了光声光谱中的弱光谱信号.首先利用自己设计的仪器装置实现光声光谱的一阶导数,在此基础上,根据导数光声光谱的数据选择合理的分析小波,将光声光谱信号分解为不同频率信号的叠加,被分解的信号满足线性性质且原信号的峰值信息保持不变,由频率的差异可区分出光声信号和噪声信号,从而提取出光声光谱中的弱光谱信号.结合物理方法与软件方法的分析结果,准确地测量了氙灯的输出光声光谱中3个不明显的弱峰值,位置分别为699.7nm、753.4nm和776.5nm.该方法可以更准确地提取出光声光谱的峰值信息,有效地提高了光声光谱的测量精度,为光声光谱分析法在生物医学及化学分析中的应用提供了一种更精确的分析方法.     

关于恒速物体间接做功的结论及应用

利用多种方法推导了恒速物体在发射质点过程中对质点间接做功的公式及有关结论, 探究了不同参考 系中某个力做的功、 某个物体做的功, 以及媒介物体对加速物体做的功或提供的能量的计算方法, 并对相关物理问 题从多角度进行解答     

Effects of multiple interruptions with trimethylindium-treatment in the InGaN/GaN quantum well on green light emitting diodes

In this study, the influence of multiple interruptions with trimethylindium(TMIn)-treatment in InGaN/GaN multiple quantum wells(MQWs) on green light-emitting diode(LED) is investigated. A comparison of conventional LEDs with the one fabricated with our method shows that the latter has better optical properties. Photoluminescence(PL) full-width at half maximum(FWHM) is reduced, light output power is much higher and the blue shift of electroluminescence(EL) dominant wavelength becomes smaller with current increasing. These improvements should be attributed to the reduced interface roughness of MQW and more uniformity of indium distribution in MQWs by the interruptions with TMIn-treatment.