原始数据中束流相关本底的分离

束流相关本底处理的不确定性是在BES/BEPC上进行R值测量的主要误差来源之一,提出从原始数据中分离出束流相关样本的新方法, 并把此样本用于调节强子产生器LUARLW的参数,以减小强子探测效率的系统误差, 提高R值的测量精度.     

用于木材水分检测的单边核磁共振传感器设计

为了实现对木材水分的无损检测,设计了一种单边核磁共振（unilateral nuclear magnetic resonance,UMR）传感器,该传感器由单边磁体、抗涡流板、射频线圈、阻抗匹配和调谐电路构成．在距离传感器表面上方75 mm处的50 mm×50 mm的平面内,建立了71.1 mT（共振频率为3.027 MHz）的静态磁场．本文详细介绍了该传感器的设计思路和实现方法,并开展了初步的木材水分无损测量实验．对圆柱形树桩的径向水分分布进行了一维扫描测量,观察了水分由树皮向树芯逐步深入过程中横向弛豫时间（T₂）的变化规律,还使用UMR仪对木材干燥过程中水分的挥发进行了测量.实验结果表明,随着干燥的加剧,被测样品T₂谱的长T₂波峰明显左移、积分面积渐减,而且积分面积与木材样品含水率呈正比．本文为木材研究提供了一种便携的NMR测量设备设计方案,且可以实现野外活体树木的无损测量．     

半导体纳米粒子SERS基底对大肠杆菌的无损检测研究

很多致命的疾病都与细菌感染密切相关,快速、准确地检测和鉴定细菌及微生物,一直是微生物学家及有关科研工作者追求的目标,拉曼光谱可以提供丰富的谱图信息,而表面增强拉曼光谱(SERS)有很高的检测灵敏度,然而一些贵金属SERS基底却容易使蛋白质变性,影响检测结果。以大肠杆菌(E.Coli)作为目标检测细菌,首先检测到大肠杆菌的拉曼光谱,之后采用两种不同的SERS基底(ZnO,Ag溶胶)进行检测。结果表明Ag溶胶基底有很强且较丰富的SERS信号,但是相对于E.Coli的本体拉曼谱峰有较大位移,说明与银溶胶相互作用的细菌存在一定的蛋白质变性过程;而ZnO纳米粒子与细菌作用的SERS信号虽然较弱,但是与E.Coli的本体拉曼信号较为相似,说明ZnO纳米粒子对E.Coli本体基本无损,这将有利于SERS在生物体系的无损检测。该结果可以为利用生物相容性好的半导体SERS基底进行细菌的检测提供有益的参考。     

用电光采样法测量相对论电子束团长度

介绍了电光采样法测量电子束束团长度的实验原理和装置,理论分析并模拟计算了被测电子束团库仑场分布、ZnTe晶体的电光效应与束团电场的关系,并利用琼斯矩阵法分析了探测光通过电光晶体时在束团电场作用下的偏振变化、测量信号与束团长度的关系等。分析表明:测量中应使束团库仑场垂直于ZnTe的［001］方向,探测光偏振方向与ZnTe晶体y″轴成45°或者135°夹角,1/4波片快轴与探测光偏振方向夹角应取45°,这时平衡探测器输出信号与束团库仑场Eb成正比。1/4波片的作用是将电光晶体的工作点从非线性段移到线性段,平衡探测的作用是简化信号与Eb的关系,并提高信噪比。为实际测量应用提供参考。     

Nuclear uncertainties in the s-process simulation

The heavy elements in the Universe are formed during the s- and r-processes mainly in AGB stars and supernovae, respectively. Simulation of s- and r-nucleosynthesis critically depends on the neutron capture and weak decay rates for all the nuclei on the reaction chain. The present work analyzes systematically the neutron capture rates (cross sections) for the s-process nuclei, including ～3000 rates on ～200 nuclei. The network calculations for the constant temperature s-process have been performed using the different data sets selected as the nuclear inputs to investigate the uncertainties in the predicted s-abundances. We show that the available cross sections of neutron capture on many s-process nuclei still carry large uncertainties, which lead to low accuracy in the determination of s-process isotope abundances. We analyze the neutron capture cross section data for the same unique isobar nucleus accorded by year from previous work. Such an analysis indicates that the s-process has been studied for more than fifty years and there exist two research stages around 1976 and 2002, respectively. The needs and opportunities for future experiments and theoretical tools are highlighted to remove the existing shortcomings in the neutron capture rates.     

一种多光路光轴平行性检测系统

介绍一种用于检测多光路光电设备光轴平行性的测试系统,该系统采用准直平行光管提供无穷远目标,并融合了CCD图像采集处理和计算机技术,通过计算目标靶十字中心和激光光斑中心之间在CCD上的像素跨距,计算出红外、可见光以及激光三轴相互间的平行性误差,系统的计算误差小于5。     

用数码相机实现未琅禾费衍射测量细丝直径

介绍利用激光获得丝夫琅禾费衍射图样，并采用数码相机实现计算机辅助非接触自动测量细丝直径的方法，以及将其用于设计性实验的尝试。     

粒子-转子模型和推转壳模型中的能谱统计分析

用粒子–转子模型和推转壳模型研究了6个粒子分别填充在单j壳和双j壳上的混沌行为.分析了单j壳和双j壳情况下能谱的最近邻能级间距分布和谱刚度随自旋及推转频率的变化,结果表明,当组态空间大小不变时,系统在双j壳(g_7/2+d_5/2)情况下比在单j壳(i_13/2)情况下更规则,而当组态空间从单j壳(i_13/2)扩大到双j壳(i_13/2+g_9/2)时,系统的混沌程度变化不大.同时比较了将6个粒子的两体相互作用分别取为δ力和对力时的系统的混沌行为     

Beam Parameters for End Diffraction of TE0 Mode of Planar Waveguide

The relation between diffractive beam parameters and normalized frequency is analyzed that leads to two improved Tormulas for two kinds of mode-field halT-widths and several formulas for divergence angle as well as beam propagation factor. The numerical calculation indicates that the maximal relative error is less than 0.5% within a reasonable parameter range.     

High Power Continuous-Wave Actively Mode-Locked Diode-Pumped Nd:YAG Laser

We demonstrate a diode-pumped cw mode-locked Nd：YAG by an acousto-optic mode locker. A mode-locked pulse with duration of 345 ps and output power of 12 W is obtained. The resonator design shows three advantages： a larger mode volume, high stability against thermal lens fluctuations, and excellent beam quality with TE00 mode. Different from previous active mode locking designs, we employ a frequency stabilizer and a phase-lock loop circuit to ensure the mode locking stable operation.