相对论平均场框架下偶-偶核奇-偶核计算误差的系统研究

在相对论平均场理论框架下, 用NL-3和NL-Z两组相互作用参数研究了4个同位素链²⁸Ni,⁵⁴Xe,⁷⁸Pt,⁹⁴Pu的基态性质. 发现,在Hatree近似下奇A核结合能理论计算值与实验值的相对误差反而普遍比偶偶核小. 这说明用相对论平均场理论,即使不考虑矢量介子的空间分量,仍可以比较可靠地计算奇A核结合能.     

镜像核12B和12N的相对论平均场理论研究

在包含了奇时间分量的三轴形变相对论平均场理论框架下, 研究了轻奇-奇镜 像核¹²B和¹²N的基态性质, 如结合能差、均方根半径以及形变等, 并且分析了矢量介子场空间分量对基态性质, 特别是单粒子能级的影响.     

157,159Tb和155,157Gd集体能谱研究

基于相互作用玻色子-费米子模型的观点,阐述一种研究奇质量核集体态的微观方法.导出了模型哈密顿量并用于计算^157,159Tb和^155,157Gd的能谱.数值结果与实验定性符合较好.     

相对论平均场理论研究原子核的磁矩

采用球形以及三轴形变的相对论平均场理论研究了满壳附近质量数A=133, 207, 209的原子核的磁矩, 分析了相对论效应以及核芯极化对磁矩的影响. 计算结果表明用包含矢量介子空间分量(奇时间分量)的三轴的相对论平均场理论 可以很好的描述满壳附近重质量区原子核¹³³Sb以及²⁰⁹Bi的磁矩.     

Brans-Dick宇宙中的轻子数生成

讨论了\,Brans-Dicke\,理论中的辅助性标量,\phi,在宇宙的重子数不对称起源中所扮演的可能角色.在,Morganstern,关于,Brans-Dicke(BD)宇宙学的一系列工作的基础上, 讨论了这个引力性标量场的导数和重子流, J^μB ,或者重子--轻子'流, J^μB-L ,的耦合效应. 发现由这个耦合形成的自发重子数生成机制, 只要其中大统一发生的时标足够提前, 就可以产生足够的重子数不对称,n_B/s～10^-10. 此外,也研究了由,Davoudiasl,引进的里奇标量,R,的导数和重子流之间的相互作用耦合在辐射为主的,BD,宇宙中的重子数生成效应. 结果表明, 在此情况下因为,R,不再为零也同样可以获得重子数的不对称, 从而不同于爱因斯坦宇宙框架下的相关结论.     

Pentaquark Θ+对核物质状态方程的影响

假定Θ⁺通过交换有效的同位旋标量介子σ和ω与核子和它本身发生相互作用, 在密度相关的相对论平均场理论基础上研究了{p,n,Θ⁺}系统状态方程和可能形成的亚稳定态. 讨论了在不同的重子密度下质子-中子同位旋比值以及Pentaquark Θ⁺成分对系统单个重子能的影响. 计算结果表明, 在单个重子能取极小时, Θ⁺有可能在核物质中束缚存在.     

奇A Tm同位素链及[411 1/2]带退耦参数性质的研究

用准粒子组态相关的宏观一微观推转模型计算了奇A核^157一173Tm同位素链的基态、低激发态形变以及这些核的[411 1/2]奇质子带的退耦参数,并与实验结果进行了比较,着重分析了γ形变对奇ATm同位素链的退耦参数的影响,进而指出¹⁵⁷Tm的退耦参数异常可能是由于带相互作用引起的,讨论了退耦参数对Nilsson参数和形变参数的敏感程度.     

稀土区奇A核M1和E2跃迁的性质

利用推广的粒子-转子模型研究了稀土区奇A核的M1和E2跃迁的性质,指出核心的十六极形变、转动哈密顿量中的二级科里奥利作用对M1(ΔI=1)和E2跃迁几率的Signature依赖性以及对Signature的平均值有着不容忽略的影响.对¹⁵⁷Ho的计算得到了能谱的Signature分离、B(M1;ΔI=1)值和[B(E2;ΔI=1)/B(E2;ΔI=2)]^1/2比值都同实验定性相符的结果.     

Pentaquark Θ+的介质效应

在密度相关的相对论平均场理论基础上, 假定Θ⁺通过交换有效的同位旋标量介子σ和ω与其他重子发生相互作用, 研究了强子在包含Θ⁺的奇异核物质中的性质改变. 讨论并计算了介质中的Θ⁺和核子有效质量及其对重子密度的依赖关系, 分析了Θ⁺在核物质中包含的成分大小以及核子的同位旋效应对奇异核物质性质的影响, 进一步计算了不同重子组成比例下奇异核物质的标量密度ρ_S和矢量密度ρ_B的对应曲线.     

e+e－湮没过程的重子产生

本文指出(3/2)⁺与(1/2)⁺重子相对权重的改变对末态长寿命重子产额没有影响,而对(3/2)⁺重子产额改变显著.分析e⁺e^－实验资料发现对(3/2)⁺重子很强的抑制参数为0.3,由此得到的末态重子产额及产额比才能与实验符合.     

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.     

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.     

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.     

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.     

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.     

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.