Paul阱内的压缩效应与量子跃迁

处理一个一维Ｐａｕｌ阱系统中的压缩现象与量子跃迁现象，对于阱内的最强压缩态和共振跃迁（一种极不稳定状态）之间的关系作了阐述，并对利用压缩性质在阱内进行精密测量的可能性作了讨论     

Decay-mode independent searches for new scalar bosons with the OPAL detector at LEP

This paper describes topological searches for neutral scalar bosons S⁰ produced in association with a Z⁰ boson via the Bjorken process at centre-of-mass energies of 91 GeV and 183-209 GeV. These searches are based on studies of the recoil mass spectrum of and events and on a search for with and S or photons. They cover the decays of the S⁰ into an arbitrary combination of hadrons, leptons, photons and invisible particles as well as the possibility that it might be stable. No indication for a signal is found in the data and upper limits on the cross section of the Bjorken process are calculated. Cross-section limits are given in terms of a scale factor k with respect to the Standart Model cross section for the Higgs-strahlung process . These results can be interpreted in general scenarios independently of the decay modes of the S⁰. The examples considered here are the production of a single new scalar particle with a decay width smaller than the detector mass resolution, and for the first time, two scenarios with continuous mass distributions, due to a single very broad state or several states close in mass. Received: 13 March 2002 / Published online: 19 February 2003     

Measurement of the neutron electric form factor via recoil polarimetry

The ratio G _e ⁿ /G _m ⁿ of the electric to the magnetic form factor of the neutron has been measured by analyzing the polarization of the recoiling neutron in quasi-elastic scattering of longitudinally polarized electrons from deuterium at the Q ² values of 0.45, 1.15, and 1.47 (GeV/c)². The experiment has been performed in Hall C of the Thomas Jefferson National Accelerator Facility. With G _m ⁿ being known G _e ⁿ can be deduced. The preliminary results show that the lowest Q ² points follow the Galster parametrization and that the 1.47 (GeV/c)² point rises above this parametrization.Received: 30 September 2002, Published online: 22 October 2003PACS: 13.40.Gp Electromagnetic form factors - 14.20.Dh Protons and neutrons - 24.70. + s Polarization phenomena in reactions     

Measurement of high-Q e<Superscript>-</Superscript>p neutral current cross sections at HERA and the extraction of xF<Subscript>3</Subscript>

Cross sections for e^-p neutral current deep inelastic scattering have been measured at a centre-of-mass energy of 318 GeV using an integrated luminosity of 15.9 pb^-1 collected with the ZEUS detector at HERA. Results on the double-differential cross-section in the range 185 &lt; Q ² &lt; 50 000 GeV² and 0.0037 &lt; x &lt; 0.75, as well as the single-differential cross-sections , and for Q ² &gt; 200 GeV², are presented. To study the effect of Z-boson exchange, has also been measured for Q ² &gt; 10 000 GeV². The structure function xF₃ has been extracted by combining the e^-p results presented here with the recent ZEUS measurements of e⁺p neutral current deep inelastic scattering. All results agree well with the predictions of the Standard Model. Received: 2 August 2002 / Revised version: 30 January 2003 / Published online: 24 March 2003     

Charge density: A probe for the nuclear interaction in microscopic transport models

The transport properties of the ³⁶Ar +⁵⁸Ni system at measured with the INDRA array, are studied within the BNV kinetic equation. A general protocol of comparison between the N-body experimental fragment information and the one-body distribution function is developed using global variables, with a special focus on charge density. This procedure avoids any definition of sources and any use of an afterburner in the simulation. We shall discuss the feasibility of such an approach and the distortions induced by the finite detection efficiency and the completeness requirements of the data selection. The sensitivity of the different global observables to the macroscopic parameters of the effective nuclear interaction will be studied in detail.Received: 21 January 2003, Published online: 5 August 2003PACS: 25.70.-z Low and intermediate energy heavy-ion reactions - 24.10.-i Nuclear reaction models and methodsN. Le Neindre: Permanent address: Institut de Physique Nuclaire, IN2P3-CNRS, F-91406 Orsay cedex, France.     

Di-jet production in photon-photon collisionsat $\sqrt{s_{\protect\bf\mathrm{ee}}}$ from 189 to 209 GeV

Di-jet production is studied in collisions of quasi-real photons at e ⁺ e^- centre-of-mass energies from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive -clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy of the two leading jets, and as a function of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, , for different regions of . Angular distributions in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of and is presented, where is the jet pseudo-rapidity. Different regions of the - -space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.Received: 20 December 2002, Published online: 17 October 2003     

Improved search for $B_{s}^{0} - \overline{B}_{s}^{0}$ oscillations

An improved search for B _s ⁰ oscillations is performed in the ALEPH data sample collected during the first phase of LEP, and reprocessed in 1998. Three analyses based on complementary event selections are presented. First, decays of B _s ⁰ mesons into hadronic flavour eigenstates are fully reconstructed. This selection yields a small sample of candidates with excellent decay length and momentum resolution and hi gh average B _s ⁰ purity. Semileptonic decays with a reconstructed D _s ^- meson provide a second sample with larger statistics, high average B _s ⁰ purity, but a poorer momentum and decay length resolution due to the partial decay reconstruction. Finally, semileptonic b-hadron decays are inclusively selected and yield the data sample with the highest sensitivity to B _s ⁰ oscillations, as the much higher statistics compensate for the low average B _s ⁰ purity and poorer time resolution. A lower limit is set atps^-1 at 95% C.L., significantly lower than the expected limit of 15.2 ps^-1. Received: 21 February 2003 / Published online: 11 June 2003     

基于插值的全矢量有限差分法求解阶跃光波导本征模式

给出了一种适合求解阶跃折射率分布光波导本征模式的全矢量有限差分法.该方法充分考虑了电场分量在折射率分布跃变处的不连续性, 在拉格朗日插值的基础上得到了一种精度较高的差分格式.为了验证其有效性,对一种典型结构、折射率阶跃分布的波导作了计算,并与其它方法的结果作了比较.最后对不理想刻蚀情况做了模拟计算.     

基于PML边界的有限差分法及其在光波导泄漏损耗计算中的应用

利用结合完美匹配层(PML)边界的有限差分法计算了光波导的泄漏损耗.通过采用非均匀格点差分格式和反正切坐标变换的方法,有效地减小了计算量并提高了计算精度.分析了PI(polyimide)掩埋型波导和SOI(silicon-on-insulator)脊型波导两种典型结构的泄漏损耗,给出了波导结构尺寸对泄漏损耗的影响,并对有效减小泄漏损耗的方法进行了讨论.     

可调谐液晶法-珀滤光片的研究

提出了一种可用于密集波分复用系统中的新型可调谐滤光片的设计方法,该设计利用了液晶的双折射现象,以及液晶盒内法-珀效应,从理论上分析了器件的光谱特性,计算了液晶分子的折射率调制和其分子转动角度的关系.并对器件进行了性能测试.实验结果与理论吻合较好.