相对论平均场理论中的有效超子-核子相互作用

利用相对论平均场理论,结合单超核的实验数据,研究了核介质中的Λ超子–核子有效相互作用.通过符合13ΛC超核中Λ超子1s轨道的结合能实验值,给出了5组Λ超子–核子有效相互作用参数.利用这些参数组对质量数从9到2?0?8的单Λ超核和核物质中最低Λ态的束缚能进行了系统计算,得到的结果与实验值相符.     

利用手征SU(3)夸克模型研究轻超核_Λ~5He,_Λ~4He和_Λ~4H的结合能

利用手征SU(3)夸克集团模型,通过共振群方法(RGM)得到非定域的YN相互作用势和Λ超子与壳心核的相互作用势,并用其计算了轻Λ超核5ΛHe,4ΛHe和4ΛH的结合能.计算结果表明,手征SU(3)夸克集团模型不仅能较好地描述Λp散射,也能较好地描述轻Λ超核的结合能.由于利用共振群方法(RGM)直接抽取的非定域YN相互作用势更为准确,因此计算得到的轻Λ超核5ΛHe,4ΛHe和4ΛH的结合能更符合实验数据,同时,这也为将来研究超核和多夸克体系确定了一套更为精确的模型参数.     

基于手征SU(3)夸克集团模型的YN相互作用和轻超核研究

采用基于手征SU(3)夸克集团模型的YN相互作用位,计算了轻Λ超核5ΛHe,4ΛHe和4ΛH的能谱.结果显示,近似的等效定域ΛN相互作用位不能给出正确的超核结合能,而非定域ΛN位能给出超核5ΛHe结合能的合理范围以及超核4ΛHe和4ΛH能级的正确顺序.这表明YN相互作用的非定域性起着重要的作用.计算中采用了2套模型参数,计算结果正好给出实验值的上下限.这表明超核的实验数据可以提供更多的信息来进一步约束YN相互作用,以弥补YN散射实验数据的不足.利用超核实验数据来优化选择YN相互作用参数是有可能做得到的.     

重稀土高氯酸盐甲基苯甲酰甲基亚砜配合物的合成及Tb3+的发光

合成了重稀土高氯酸盐甲基苯甲酰甲基亚砜配合物RE(ClO4)3·L5·C2H5OH(RE=Gd,Tb,Dy,Tm,Yb;L=C6H5COCH2SOCH3).经元素分析、稀土络合滴定、摩尔电导及热重分析确定了配合物的组成,测定了配体及配合物的IR谱、1H NMR及铽配合物的磷光光谱、荧光激发和发射光谱,根据荧光发射光谱数据计算了铽配合物的各能级值.     

利用手征SU(3)夸克模型研究轻超核5ΛHe,4ΛHe和4ΛH的结合能

利用手征SU(3)夸克集团模型，通过共振群方法(RGM)得到了非定域的YN 相互作用势和Λ超子与壳心核的相互作用势,并计算了轻Λ超核5ΛHe,4ΛHe和4ΛH 的结合能. 计算结果表明，手征SU(3)夸克集团模型不仅能较好地描述Λp散射，也能较好地描述轻Λ超核的结合能. 由于利用共振群方法(RGM)直接抽取的非定域YN相互作用势更为准确，因此计算得到的轻Λ超核5ΛHe ,4ΛHe 和4ΛH 的结合能更符合实验数据，同时，也为将来的超核和多夸克体系确定了一套更为精确的模型参数.     

超核的α集团结构和Λ17O的Λ分离能

用超核的α集团结构和Λ-α相互作用唯象位计算了13ΛC的Λ分离能,得到与实验数据符合甚好的结果,在此基础上进一步预言了17ΛO的Λ分离能,得到与经验值符合得最佳的结果,优于现有国际上的理论计算.     

亚甲蓝褪色光度法测定痕量溴酸根

在盐酸介质中 ,以 Na Cl为催化剂 ,Br O-3 氧化亚甲蓝褪色 ,建立了分光光度法测定痕量溴酸根的新方法。研究了溴酸根氧化亚甲蓝褪色的最佳条件 ,最大吸收波长 λmax=6 6 8nm,表观摩尔吸光系数为 4 .2 4×1 0 4L· mol-1 · cm-1 ,Br O-3 的浓度在 5× 1 0 -8— 4× 1 0 -6mol· L-1 范围内符合比耳定律 ,回归方程为 :ΔA=9.372× 1 0 4C 0 .0 5 5 82 ,相关系数 r=0 .9993。方法用于化学试剂中溴酸根测定得到了较好的分析结果。     

ZnH分子激发态的电子结构和跃迁性质的理论计算

采用高精度的多参考组态相互作用方法计算了ZnH分子的能量最低四个离解限Zn(~1Sg)+H(~2Sg),Zn(~3P2u)+H(Sg),Zn~+(~2Sg)+H~-(~1Sg)和Zn(~1Pu)+H(~2Sg)对应的7个Λ-S态的势能曲线.计算中考虑了Davidson修正、标量相对论效应、自旋-轨道耦合效应和芯-价电子关联.基于计算的Λ-S和?态的势能曲线,数值求解一维径向Schr?dinger方程得到了束缚电子态的光谱常数,理论计算结果与之前的实验结果符合较好.计算得到了7个Λ-S态的电偶极矩随核间距的变化曲线,分析了电子组态成分变化对电偶极矩和成键性质的影响.计算结果表明,C~2Σ~+态是一个离子对态.进一步地,分析了避免交叉点附近?态的Λ-S态组成的变化规律,讨论了避免交叉现象对跃迁偶极矩的影响.基于计算的跃迁偶极矩、Franck-Condon因子和振动能级信息,给出了束缚激发态(2)1/2,(3)1/2,(4)1/2和(1)3/2的v′=0—2振动能级的自发发射寿命,结果与现有实验值相符合.     

1-(8-喹啉)-3-(2-苯并噻唑)三氮烯(QBTT)分光光度法测定微量钯(Ⅱ)

研究了新显色剂 1 - (8-喹啉 ) - 3- (2 -苯并噻唑 )三氮烯 (QBTT)分光光度法测定 Pd( )的条件。在 p H1 1 .0的 Na2 B4O7- Na OH缓冲介质 ,该试剂与 Pd( )形成摩尔比为 2∶ 1的绿色稳定络合物。其最大吸收波长在 6 40 nm处 ,表观摩尔吸光系数 ε为 7.85× 1 0 4L·mol-1 ·cm-1 ,Pd( )的浓度在 0— 1 .2 μg/ m L范围内符合朗伯 -比尔定律。对 30多种共存离子的影响实结果表明 ,大多数常见离子不干扰测定。方法具有较好的选择性 ,用其直接测定催化剂样品中的微量钯 ,结果满意     

超核的α集团结构和_Λ~(17)O的Λ分离能

用超核的α集团结构和Λ α相互作用唯象位计算了 13ΛC的Λ分离能 ,得到与实验数据符合甚好的结果 ,在此基础上进一步预言了 17ΛO的Λ分离能 ,得到与经验值符合得最佳的结果 ,优于现有国际上的理论计算     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

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.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

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.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.