与运动二能级原子作用的双模光场的量子特性

用全量子化理论,研究了与运动二能级原子相互作用的双模量子化光场的量子特性,分析了场模结构对平均光子数,单模二阶相干度,两模间的相关性的影响. 研究结果表明,随着场模结构参量的增大,平均光子数回复周期变短,振荡加剧,在崩塌区域内振荡出现分裂, 同时原子运动对光场的二阶相干性有明显的影响.     

Charged particle density distributions in Au + Au collisions at relativistic heavy-ion collider energies

Charged particle pseudorapidity distributions have been measured in Au+ Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions of different parton scattering models and the important role of hard scattering processes at RHIC energies is discussed. Keywords. Relativistic heavy-ion collisions; charged hadron production; pseudorapidity distributions; centrality dependence; hard scattering processes.     

Search for the Standard Model Higgs boson with the OPAL detector at LEP

This paper summarises the search for the Standard Model Higgs boson in e ⁺ e ^- collisions at centre-of-mass energies up to 209 GeV performed by the OPAL Collaboration at LEP. The consistency of the data with the background hypothesis and various Higgs boson mass hypotheses is examined. No indication of a signal is found in the data and a lower bound of 112.7 Gev/c² is obtained on the mass of the Standard Model Higgs boson at the 95% CL. Received: 13 March 2002 / Revised version: 9 October 2002 / Published online: 13 December 2002     

Paul阱中3—20个离子的有序构形

用分子动力学方法和ＭｏｎｔｅＣａｒｌｏ方法相结合，模拟了Ｐａｕｌ阱中离子体系的阻尼冷却，系统地得到了３～２０个离子的有序构形。结果表明：离子的晶相结构随着离子数目的增加呈现出有规律的变化；同时，晶相结构的有序构形与囚禁场的赝势阱形状具有几何相似性的关联。     

复杂粒子发射对热核巨共振的影响

讨论了引起统计蒸发模型计算结果与高温热核偶极巨共振实验结果之间存在差别的因素,对比了标准CASCADE程序计算结果与加入复杂粒子发射后的计算结果,计算显示复杂粒子发射对高温热核偶极巨共振的性质有影响.     

折-衍混合超广角视场目镜系统的设计

在传统的超广角 (70°)赛得莫尔 (Scidmore)目镜的基础上 ,设计了两个折衍混合 70°视场的目镜。其中一个混合系统含有两个折衍单透镜 ,另一个含有一个折衍单透镜。所设计的混合系统与赛得莫尔目镜进行了像差和结构的比较 ,表明折衍混合目镜系统不仅在诸如垂轴像差、垂轴色差、平均场曲等光学性能方面优于传统的赛得莫尔目镜系统 ,而且在尺寸和重量上有非常显著的减少。最后讨论了衍射面的结构参量。     

催化动力学光度法测定痕量硫氰酸根的研究

基于硫氰酸根对碘氧化叠氮化钠的催化作用,建立了催化动力学光度法测定硫氰酸根的新方法.于352nm处分别测定催化体系和非催化体系的吸光度A和A_V,以△A=A_c-A定量,线性范围为1.0～700μg·L~-1,检出限1.0μg·L~-1.用于生物样品中痕量硫氰酸根的测定,结果满意.     

S earch for anomalous production of di-l epton ev ents with missing transv ers e mom entum in e + e- collisions at $\sqrt{s} = {}$183-209 G eV

In total 1317 di-lepton events with significant missing transverse momentum were identified in a total data sample of 680 pb^-1 collected at e ⁺ e^- centre-of-mass energies ranging from 183 GeV to 209 GeV. The number of di-lepton events, the dependence on centre-of-mass energy, and the event properties are consistent with expectations from Standard Model processes, predominantly W ⁺ W^- production with both W bosons decaying leptonically. This topology is also an experimental signature for the pair production of new particles that decay to a charged lepton accompanied by one or more invisible particles. No evidence for new phenomena is apparent. Upper limits are presented on the production cross-section multiplied by the relevant branching ratio squared for sleptons, leptonically decaying charginos and charged Higgs bosons. Mass limits are also given.Received: 14 July 2003, Published online: 9 January 2004     

COMPOSITION OF INDOOR AEROSOLS AT EMPEROR QIN''''S TERRA-COTTA MUSEUM, XI''''AN, CHINA, DURING SUMMER, 2004

Particle samples were collected in August 2004 both inside and outside Emperor Qin's Terra-Cotta Museum in Xi'an, China. Mass and chemical composition of total suspended particles (JSP, particles with aerodynamic diameter less than-30μm), PM2.5(particles with aerodynamic diameter <2.5μm) were determined. The average levels of indoor PM2.5 and TSP were 108.4 and 172.4 μg·m-3, respectively, with PM2.5 constituting 62.9% of the TSP mass. Sulfate ((32.4±6.2)%), organics ((27.7±8.0)%), and geological material ((12.5±3.4)%) dominated indoor PM2.5, followed by ammonium ((8.9±2.8)%), nitrate ((7.0±2.9)%), and elemental carbon (EC, (3.9±1.5)%). Particle size distribution varied with the number of tourists in the museum. The size of sulfate, organics, EC, nitrate, and ammonium was found to vary in the range of 0.43 to 3.3 μm in fraction. Ion balance indicated that the aerosol was acidic, with insufficient ammonium ions to neutralize the sulfuric and nitric acids. High concentrations of acidic aerosols will erode the Terra-cotta warriors and horses especially in the summer season with high temperature (30℃) and relative humidity (70%) and undesirable solar radiation inside the museum. More attention should be paid to protecting these precious antiques made 2000 years ago.