Anomalous Pressure Behavior of N-Cluster Emissions in GaAs0.973Sb0.022N0.005

Photoluminescence of GaAs0.973Sb0.022N0.005 is investigated at different temperatures and pressures. Both the alloy band edge and the N-related emissions, which show different temperature and pressure dependences, are observed. The pressure coefficients obtained in the pressure range 0-1.4GPa for the band edge and N-related emissions are 67 and 45meV/GPa, respectively. The N-related emissions shift to a higher energy in the lower pressure range and then begin to redshift at about 8.5GPa. This redshift is possibly caused by the increase of the X-valley component in the N-related states with increasing pressure.     

Study of Ternary Fission Produced in 12C Bombarding 209Bi Target with Medium Energy

Alternative layers of target material,which were prepared by evaporating ²⁰⁹Bi on the surface of mica foils,were irradiated with ¹²C ions.Ternary fission events in which three fragments of comparable mass were produced in 2525－47.5MeV/A ¹²C+²⁰⁹Bi reaction,were recorded by the mica detectors with 2π geometry.The observed probability ratio of ternary fission relative to binary fission in 2π geometry was modified to 4π geometry spatial in terms of the Monte Carlo method.The values of ratioes increase with the bombarding energy,and are compared with the calculation result of the cascade fission model.     

Computer design of a compact cyclotron

Here we present results of the computer design of the structural elements of a compact cyclotron by the example of HITFiL cyclotron selected as the driving accelerator that is under construction at the Institute of Modern Physics (Lanzhou, China). In the article a complex approach to modeling of the compact cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics calculations, is described. The existing design data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron are used as a starting point in the simulation. Some of the upgrades of the cyclotron structural elements were proposed, which led to substantial improvement of the beam quality and transmission.     

快反系统中平面反射镜的轻量化设计

根据快速控制反射镜系统(快反系统)对平面反射镜的设计要求,对快反镜的轻量化结构进行了优化设计。选择比刚度大、热变形系数小的碳化硅为镜坯材料,采用背部开槽式结构减重,背部3点式支撑,对不同筋宽和镜面厚度等多种轻量化方案进行了有限元分析。结果表明:筋宽越大,镜体刚度越好,但筋宽增大到一定程度时,反射镜刚度的改善程度减缓;镜面越厚,镜体内应力、自重变形越大。结合反射镜设计要求和有限元分析结果,加工制备了筋宽为4 mm,镜面厚度为4 mm的碳化硅反射镜,镜体轻量化率达55%。实测反射镜的面形精度,其RMS值不超过λ/30,与分析结果相符,满足系统的使用要求。     

PDMAEMA多重环境响应行为的NMR研究

利用原子转移自由基聚合（Atom Transfer Radical Polymerization, ATRP）合成了分子量分布较窄的聚甲基丙烯酸N, N-二甲氨基乙酯{Poly\[2 (diethylamino)ethylmethacry-late], PDMAEMA}并通过对液体核磁共振氢谱（¹H NMR）化学位移以及弛豫时间（T₁、T₂）的测量,研究了聚合物PDMAEMA的温度敏感、pH敏感以及离子敏感3种环境敏感行为. 发现聚合物链段的运动性,以及温度和离子强度诱导的相变行为,都与体系的pH值具有强依赖关系. 室温下,聚合物链段的运动性随pH值的增大而降低. 酸性条件下,聚合物表现出离子敏感性,而不表现出温度敏感性. 碱性条件下,聚合物表现出温度敏感性,不表现出离子敏感性.     

板条增益介质波前畸变诊断方法

对波前重构算法中的区域法进行了改进,使其能够应用于板条增益介质的波前畸变诊断。利用该方法对47块Nd: YAG板条增益介质沿厚度方向波前畸变进行测量,指出镀膜和加工等环节对增益介质的波前畸变可能造成的影响。按照波前畸变峰谷（PV）值对测量结果进行了统计,结果表明:增益介质造成的静态波前畸变参差不齐,测量样本中静态畸变PV值最多可达5 m以上,且仅有4.1%的增益介质静态畸变PV值小于1 m。通过选取某些增益介质使之级联,测量其组合波前畸变,发现在系统中使用两块波面互补的增益介质有助于减小系统的静态波前畸变。     

微波消解-ICP-AES测定海鸭蛋中的金属元素

建立微波消解海鸭蛋,电感耦合等离子体-原子发射光谱法检测样品中金属元素的方法。分析结果表明,15种元素的相对标准偏差(RSD,n=12)小于2%,回收率范围在91.0%-105.4%之间。该法快速,简单,可靠性高,可多元素同时测定,适用于海鸭蛋的快速分析检测。     

利用互易性电路设计降低超声流量测量的零点误差和温度漂移

超声流量测量系统中,严重影响时间差检测的准确度和稳定性的“零点误差”和“温度漂移”问题可以通过对测量系统互易性的改善加以改进。本文通过对测量系统等效电路模型的分析阐述了系统互易的成立条件,并提出了一种通过对激励和接收电路等效阻抗进行对称性设计提高测量系统互易性的测量电路。这一电路设计易于在仪表中实现,其中换能器的负载阻抗能够根据需要灵活设定。在实际测量管道上进行的实验证明,使用这样的电路设计进行流量测量,能够大幅降低零点误差并抑制温度漂移,使得流量测量结果更加准确稳定。     

磁化铁氧体覆盖二维导体目标FDTD分析的移位算子方法

采用移位算子方法把时域有限差分法推广应用于二维磁各向异性色散介质—磁化铁氧体中.证明了电磁波横向入射二维轴向磁化铁氧体目标情形下,电磁波可按目标的轴向分解为横电波(TE波)和横磁波(TM波),且TE波的散射特性与铁氧体介质无关,而TM波的散射特性与介质电磁参量密切相关,同时对其物理原因进行了分析.通过采用移位算子方法处理磁化铁氧体频域本构关系,得到该情形下目标电磁散射的移位算子时域有限差的迭代计算公式,同时解决了电磁波在各向异性和频率色散介质中传播的问题.计算了轴向磁化铁氧体涂敷VonKarman型导体柱的TM波双站雷达散射截面,分析了铁氧体参量对目标双站雷达散射截面的影响.结果表明:恰当地选择铁氧体参量能有效地减少目标的雷达散射截面,本文时谐因子取exp〔jωt〕.     

Determination of the ~(12)C(p, γ)~(13)N reaction rates fromthe ~(12)C(~7Li,~6He)~(13)N reaction

The angular distribution of the 12C(7Li,6He)13N reaction at E(7Li) = 44.0 MeV was measured at the HI-13 tandem accelerator of Beijing, China. The asymptotic normalization coefficient (ANC) of 13N → 12C + p was derived to be (1.64 ± 0.11) fm-1/2 through the distorted wave Born approximation (DWBA) analysis. The ANC was then used to deduce the astrophysical S (E) factors and reaction rates for the 12C(p,γ)13N direct capture reaction at energies of astrophysical relevance.