含外规范场和动力学费米子自能的狄拉克算符及费米子凝聚

将非阿贝尔规范理论中狄拉克算符行列式的计算从传统的只能含有硬费米子质量项的情况推广到可以含有动量相关的费米子自能的情况，并且行列式与费米子凝聚的计算都被推广到使之能够含有任意的外规范场. 关键词： 费米子自能 外规范场 狄拉克算符的行列式 费米子凝聚     

Systematic investigations of the multi-element preconcentration from copper by precipitation of the matrix as copper(I) oxide and copper(I) thiocyanate

Two methods for multi-element preconcentration from copper by reductive matrix precipitation are presented. In systematic investigations on the coprecipitation behaviour of Ag, Al, Au, Bi, Cd, Co, Cr, Fe, Ga, In, Mn, Mo, NJ, Pb, Sb, Se, Sn, Te and Zn during precipitation of the copper matrix as Cu₂O or CuSCN, the separation parameters were optimized. By combination with a hexamethyleneammonium hexamethylenedithiocarbamate collector precipitation, a concentration of 8 elements (Cu₂O precipitation) or 13 elements (CuSCN precipitation) in a small volume was achieved. The limits of detection of the procedures are, depending on the element, 0.1–5 μg g^?1 for flame atomic absorption spectrometry (AAS) and 0.01–0.1 μg g^?1 for graphite furnace AAS. The relative standard deviations are about 3%. The analytical performance of the procedures is compared with that of an electrolytic copper separation.     

Infra-red free-carrier absorption due to impurity scattering in semiconducting quantum well structures

The theory of free-carrier absorption (FCA) is developed, in the extreme quantum limit when the carriers are assumed to populate only the lowest quantized energy level, for quasi-two and one-dimensional semiconducting quantum well structures where the carriers are scattered by ionized impurities. The radiation field is assumed to be polarized in the plane of the layer in the quasi-two-dimensional case and along the length of the wire in the quasi-one-dimensional case. Expressions for FCA are obtained for the cases where the impurities are either in the well (background impurities) or outside the well (remote impurities). Variation of FCA is numerically studied with photon frequency and well width.     

ZnS中电子陷阱能级对光生电子弛豫过程的影响

采用微波吸收法,测量了在不同助熔剂条件及不同气氛下烧制的ZnS材料受到超短激光脉冲激发后的光电子衰减过程,并且测量了材料的热释光曲线。样品A采用过量的SrCl作为助熔剂,在1150℃下灼烧制备而成;其热释光曲线显示材料中有浅电子陷阱,电子陷阱密度小,光生电子衰减过程为双指数衰减过程,快过程寿命为45ns,慢过程寿命为312ns。样品B中加入了少量的NaCl作为助熔剂;热释光曲线显示有浅电子陷阱和深电子陷阱,且都有较高的密度,其光电子寿命为1615ns。在NH₄Br气氛中烧制样品C,热释光谱显示只有浅电子陷阱形成,光电子寿命为1413ns。结果表明材料的光电子寿命和浅电子陷阱密切相关,浅电子陷阱密度越大,光生电子寿命越长,深电子陷阱对光生电子瞬态过程影响很小。     

非对称量子阱中非线性光学吸收系数的计算

非对称量子阱中的非线性光学效应因其潜在的实用价值而引起人们的广泛关注,而量子阱内带间的光学吸收问题对研究远红外光学探测器件具有重要的理论指导意义.以Pschl-Teller势阱为例研究了影响非对称量子阱中的非线性光学吸收系数的因素.考虑到带间的电子弛豫,用量子力学中的密度矩阵算符理论导出了Pschl-Teller势阱中的线性与三阶非线性光学吸收系数的表达式.因该势阱中有两个可调参数,通过调节系统的参数,发现该系统的非线性光学吸收系数呈规律性的变化.以典型的GaAs/AlGaAs非对称量子阱为例作了数值计算,通过调节系统的参数,数值计算结果表明,入射光强以及系统的非对称性对量子阱的非线性光学吸收系数有较大的影响,从而为实验上研究非对称量子阱的非线性光学效应提供了必要的理论依据.     

氪灯和氙灯光谱强度分布和光谱效率测量

氪灯、氙灯光谱强度分布和光谱效率测量是反映氪灯、氙灯性能的关键指标。介绍了一套新型的氪灯、氙灯光谱强度分布和光谱效率检测系统。该系统是一套测量连续发光灯和脉冲闪光灯发光性能及效果的综合检测设备。该检测单元采用计算机进行操控,人机界面良好,便于检验人员进行氪灯和氙灯光谱强度分布和光谱效率的批量检测。检验人员利用该系统可进行装机模拟试验和可靠性试验,可对氪灯和氙灯的性能进行必要的分析研究,不断地积累了氪灯和氙灯的检验数据和经验。     

推广x重新标度模型的重标度参数经验公式

给出了推广x重新标度模型的重标度参数经验公式,其中建立了重标度参数与原子核的平均结合能之间的联系,由该公式可以得出A≥12的所有核的重标度参数值,利用这些参数值可以计算有关核过程并做出预言.     

在BEPC上建造γ束线站的分析

考虑电子的反冲并利用康普顿散射,研究了激光同步辐射光源(LSS)辐射的光子波长、光子能量。结果表明,对于不同的γ,LSS辐射的光子波长和能量有不同的近似公式。当γ<<λ1/4λe时,LSS辐射的光子波长λ2≈λ1/4γ2,能量(εc2≈4γ2εc1;当γ>>λ1/4λe时,LSS辐射的光子波长λ2≈λe/γ,能量cε2≈m0γc2;结果表明,LSS辐射的条件是种子激光的波长λ1大于电子的物质波波长λm;LSS辐射的极值波长是λ2m ax=h/m0γv,极值能量是cε2m ax=βeε;本文后半部分提出了利用北京正负电子对撞机的强流高亮度电子束与激光的康普顿背散射产生单色γ射线的建议。     

A Reliability Analysis of Calculated Results for Odd-Even and Odd-Odd Nuclei in Relativistic Mean-Field Theory

We calculate the binding energies of Ni, Cu, Xe, Cs, Pt, Au, Np, Pu isotope chains using two interaction parameter sets NL-3 and NL-Z, and compared the relative errors of the even-even nuclei with those of odd-even nuclei and odd-odd nuclei. We find that the errors of binding energy of odd-even and odd-odd nuclei are not bigger than the one of even-even nuclei. The result shows that comparing with even-even nuclei, there is no systematic error and approximation in the calculations of the binding energy of odd-even and odd-odd nuclei with relativistic mean-field theory. In addition, the result is explained theoretically.     

Irregularities of distribution with respect to strips

Summary A lower bound is established for the strip discrepancy of a broad class of point distributions. The bound implies unbounded strip discrepancy for equally weighted point distributions under favorable conditions. The methods of proof use notions from integral geometry.