海平面宇宙射线重粒子的质量谱及通量的测量

本文介绍了一个由飞行时间测量系统构成的实验装置,描述了这个实验装置的各个组成部分和它的性能,并给出了海平面宇宙射线重粒子的质量谱及通量的测量结果。     

闪烁计数器阵列定位系统

该闪烁计数器阵列定位系统,即闪烁计数器描迹仪,不但可以确定带电粒子通过的位置,还可以用做触发计数器。在用做触发计数器时,它还具有选择落入该阵列的带电粒子数目的能力。该描迹仪为8×8闪烁计数器阵列,每条闪烁体（ST401型）为40×5×0.6cm³。配用GDB50光电倍增管。阵列面积为40×40cm²。我们自制了快电子学系统和数据读取系统,在与微处理机联试过程中,工作稳定可靠。造价低廉。     

First-principles study on the electronic structure and optical properties of T12Cd2（SO4）3 and Rb2Cd2（SO4）3

With the help of ab initio full-potential linearized augmented plane wave （FPLAPW） method, calculating the electronic structure and linear optical properties is carried out for XCd2（SO4）3 （X =Tl, Rb）. The results show that Tl2Cd2（SO4）3 （TlCdS） has a larger band gap than Rb2Cd2（SO4）3 （RbCdS） and the energy bands for RbCdS are more dispersive than those of TlCdS. From their partial densities of states （PDOS）, we have observed that the hybridization between S ionic 2p and O atomic 2p orbitals forms SO4 ionic groups. The remarkable difference between RbCdS and TlCdS is, however, the degree of hybridization between cation （Tl and Rb） and its surrounding oxygen atoms. In the view of quantum chemistry, the strong p-d hybridization indicates the existence of their cation ionic bonds （Cd-O, Rb-O, and Tl-O）. The calculations of TlCdS and RbCdS show their optical properties to be less anisotropic. Their anisotropies in the optical properties mainly occur in a low photon energy region of 5-16 eV.     

Electronic Structure and Optical Properties of Semiconducting Orthorhombic BaSi2

Full potential linearized augmented plane wave （FPLAPW） method calculations are carried out for semiconducting orthorhombic BaSi2. The optical properties and the origin of the different optical transitions are investigated. Our calculated band gap of 1.0918eV is indirect, which is in good agreement with the experimental result. The bonds between Ba and Si are considered to be electrovalent bond. The anlsotropy in the imaginary part ε2（w） and real part εl（w） of the optical dielectric tensor are analysed. The contributions of various transition peaks are explained from the imagnary part of the dielectric function.     

采用带微型预处理柱和分离柱的FIA分光光度系统同时测定硅和磷

用阳阴离子交换柱和流动注射分析组合,建立了在线预处理和预分离同时测定磷和硅的FIA方法。用本法测定了头发、淡菜、茶叶、马尾藻和大米中的硅和磷。方法的测定范围为1．0mg/L-24mg/L(PL4^3-),0.5mg/L-12mg/L(SiO3^2-),回收率：96.7%-99.0%(PO4^3-),100%-102%(SiO3^2-);RSD(PO4^3-)=1.3%,RSD(SiO3^2-)=1.8%。     

宇宙线μ子天顶角分布在线测量

本文给出了用闪烁计数器描迹仪构成的望远镜阵列测量宇宙线μ子天顶角分布的初步结果. 天顶角的范围为0°到17.7°十种不同的角度值. 实验结果表明, 宇宙线μ子强度对天顶角θ的依赖关系服从cos^2.6θ分布规律. 用描迹仪望远镜阵列测量天顶角分布的优点是: 角度分辨率好, 而且还可以同时获取多个角度的数据.     

Continuous Variable Entanglement and Violation of Bell Inequality for Two Modes in a Three-Level Cascade Atomic System

Continuous variable entanglement and violation of Bell inequality for two modes are investigated in a three-level cascade atomic system. Entanglement of the system is demonstrated according to the entanglement criterion [Phys. Rev. Lett. 84 （2000）2722]. Violation of Bell inequality is studied within the framework of a quantum theory of multiwave mixing. It is shown that there are some states that are entangled but do not violate the Bell inequality.     

Charge transport and shot noise on the surface of a topological insulator with a magnetic modulation

In this paper, we investigate the transport features and the Fano factor of Dirac electrons on the surface of a three-dimensional topological insulator with a magnetic modulation. We consider a hard wall bounding condition on the edge of the topological insulator, which implies that a surface state of the topological insulator is insulating. We find that a valley of conductivity at the Dirac point is associated with a Fano factor peak, and more interestingly, this topological metal changes from insulating to metallic by controlling the effective exchange field.     

Temperature dependence of the energy-level shift induced by the Bose—Einstein condensation of photons

We investigate the energy-level shift of a hydrogen atom in a two-dimensional optical microcavity, where there exists a Bose-Einstein condensation of photons. It is found that below the critical temperature T c , the energy-level shift of the bound electron is dependent on temperature, and it is a monotonically increasing function of the absolute temperature T . Especially, at the absolute zero temperature, the energy-level shift entirely comes from the Lamb shift, and the atom can be treated approximately, that is, in vacuum.