N、△重子谱中负能级分量的作用

利用瞬时近似的Bethe-Salpeter方程,并且考虑了Dirac旋量中负能级分量对单胶子交换势的修正,对N、△重子谱进行了计算.结果发现负能级分量的考虑对势参数,尤其是对αs有显著的影响,但对整个N、△重子谱的改变不大.     

重子谱中的自旋–轨道耦合力

在组份夸克势模型的框架下,用几种夸克势模型对重子谱中N和Λ的几组L?=1负宇称激发态自旋轨道劈裂进行了分析,指出有的模型在引进了一项半唯象的自旋轨道耦合势后能解释这几组态的自旋轨道耦合能级劈裂的实验值     

N—N相互作用中自旋轨道耦合力的夸克模型

在夸克－夸克相互作用中考虑了单胶子交换的自旋轨道耦合力、由禁闭势导出的自旋轨道耦合力、由手征场σ交换提供的自旋轨道耦合力以及由双胶子交换提供的自旋轨道耦合力，从而可以统一地解释重子谱中的自旋轨道耦合效应及Ｎ－Ｎ散射中的各个分波的相移．     

夸克势模型中的重子–重子相互作用自旋–轨道耦合势

在夸克－夸克自旋－轨道耦合势中引入了由海夸克效应产生的、与颜色自由度无关的自旋－轨道耦合势．并定性地讨论了这个势对重子谱及重子－重子相互作用计算中的影响．     

夸克势模型中的重子－重子相互作用自旋－轨道耦合势

在夸克－夸克自旋－轨道耦合势中引入了由海夸克效应产生的、与颜色自由度无关的自旋－轨道耦合势．并定性地讨论了这个势对重子谱及重子－重子相互作用计算中的影响．     

大N_c集体激发理论下的重子共振态

最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论,该理论恰好是SU(6)夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现,重子共振态谱公式能够与2 Ge V以下重子谱良好吻合。     

奇特的"五夸克态"和重子中的五夸克成分

文章简要介绍了奇特的θ^＋五夸克态、质子中的奇异夸克成分和重子激发态中的五夸克成分等重子谱和重子结构方面的一些最新前沿进展．最新的高统计量实验结果表明，轰动一时的suudd五夸克态θ^＋（1540）很可能不存在．而最新的几个电弱相干实验给出一致的结果：质子的奇异磁矩和奇异半径很可能不为零，且均为正．理论分析表明，这意味着质子中的ssuud成分很可能主要是以夸克对有色集团的形式存在，而不是以传统的介子云无色集团的形式存在．对最轻的负宇称核子激发态N^＊（1535）一些性质的最新研究支持这种关于重子中的五夸克成分的新图像．     

重子谱中的中程相互作用及其对N-N核力的影响

本文基于夸克势模型, 在QCD单胶子交换势和禁闭的谐振子位势之上, 引入唯象的夸克中程势, 去拟合N≤2的非奇异重子谱. 结果表明: 适当形式的夸克中程势能使2GeV以下的重子谱与实验较好符合, 用此有夸克中程势的夸克位势我们还探讨了N-N相互作用.     

核介质中核子－核子散射截面的BHF微观计算

在Ｂｒｕｅｃｋｎｅｒ－Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＢＨＦ）框架下，计算了核介质中核子－核子（Ｎ－Ｎ）散射总截面．计算中，Ｎ－Ｎ相互作用势采用Ｐａｒｉｓ势的可分离表示，单粒子谱采用连续选择．计算结果表明，质子－质子散射及质子－中子散射的总截面随核密度的增加而强烈地减小，特别是对低能散射．对结果作了简单的讨论，并与已有的一些计算结果进行了比较．     

^127I的核新能级纲图

利用^124Sn(^7Li,4n)^127I反应研究了^127I核的在束γ谱，建立了包括25个新能级和52条新γ射线构成的新能级纲图。将基于πh11/2粒子态（11／2^-)的负宇称能级推高到（35／2^-)，在较重的^127I中得到了退耦合能级结构，由于在两个正宇称带△I＝2能级系列中观测到了强的带间跃迁，建议此带的主要成分为g7/2质子的组态，另外还观测到了两个正宇称△I＝2和△I＝1能级系列，它们可能基于πd5／2的单准粒子带和一个3准粒子带。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.