143 Pm高自旋态研究

通过熔合蒸发反应128Te(19F,4nγ)布居了143Pm的高自旋态,利用在束γ谱学方法,对143Pm的高自旋态核结构进行了研究.测量了γ射线单谱和γ-γ符合谱,并进行了γ射线各向异性以及DCO比率分析,建立了激发能高达10535.4keV的能级纲图,其中包括新发现的32条γ射线和17个新能级.用弱耦合模型对143Pm的晕态能级结构进行了解释.     

壳模型对高自旋态143Pm核素结构分析

利用包含剩余作用的核壳模型，从143Pm高自旋能级核结构出发进行理论上探求；并计算143Pm退激跃迁几率，与实验数据进行对比. 比较了两种不同的核子有效势函数，按照γ跃迁链对143Pm进行理论与实验分析；特别利用核子分布主态结构和自旋能级对应的γ跃迁级链进行比较. 程序采用OXBASH程序     

141Nd激发态的在束γ谱学研究

通过130Te(16O,5nγ)141Nd反应布居了141Nd的高自旋态能级. 对反应产生的在束γ射线进行了γ射线单谱和γ-γ符合测量. 建立了激发能达7614.5keV的141Nd能级纲图,新发现了12条γ射线和15个能级. 基于实验测量的γ跃迁各向异性,建议了141Nd部分能级的自旋值. 用一个h11/2价中子空穴与142Nd核芯晕态的耦合可以定性地解释141Nd的能级结构.     

双奇核142Pm高自旋态能级纲图

利用能量为75—95MeV19F束流,通过反应¹²⁸Te(¹⁹F,5nγ)¹⁴²Pm研究了双奇核¹⁴²Pm的高自旋态能级结构.实验中进行了γ射线的激发函数、γ射线单谱和γγ符合测量.建立了激发能达7030.0keV的¹⁴²Pm的能级纲图,其中包括新发现的25条γ射线和13个新能级.基于实验测量的γ跃迁各向异性度,建议了¹⁴²Pm能级的自旋值.     

94Mo高自旋态能级纲图

通过重离子融合蒸发反应^16O(^82Se 4n)^94Mo布局了^94Mo核的高自旋态．利用多探头探测器阵列GASP进行了在束γ测量，从而重新研究了^94Mo核的高自旋态能级结构．基于新发现的一些重要的连接跃迁，对^94Mo核的高自旋态能级纲图做了重要修改．将新的能级结构与壳模型计算进行了比较和讨论．结果表明要正确的描述^94Mo核的高自旋态(自旋值大于14)能级结构，应考虑价中子在d5／2，g7／2和h11/2轨道上的激发．     

中子数N=50核88Sr的高自旋态

在用82Se束流和天然Ba靶之间的深部非弹反应研究类靶余核激发态时,Ba靶严重氧化,88Sr的激发态由16O与82Se之间的融合蒸发反应产生,通过对束γ谱学方法测量了88Sr的退激γ射线,提取了γ跃迁的DCO系数和角分布各向异性因子,对所有能级进行了自旋指定,在已知能级之上观测到了两个高自旋异性因子,对所有能级进行了自旋指定,在已知能级之上观测到了两个高自旋能级结构,自旋,激发能分别达到13h,8520KeV和12h,7909KeV,根据能级衰变特征和邻近N＝50同中子素的能级结构系统性,对高自旋态的组态进行了讨论。γ     

^209Fr的能级结构研究

利用能量为 90— 1 0 5MeV的16 O束流 ,通过197Au( 16 O ,4n)反应研究了2 0 9　Fr的高自旋态能级结构 .进行了γ射线的激发函数、γ γ延迟符合及γ射线的角分布测量 .首次建立了由 2 1条γ射线构成的2 0 9Fr的能级纲图 ,其中包括一个半寿命为 ( 52± 2 0 )ns的同质异能态 .基于2 0 9Fr与2 0 8Rn低位能级结构的相似性 ,用一个h9/ 2 价质子与2 0 8Rn激发态的弱耦合解释了2 0 9Fr的低位能级结构 .     

146Sm核高自旋态的实验观测

用能量为95MeV的¹³C束流,轰击天然厚Ba靶,对¹⁴⁶Sm的高自旋态进行了实验研究,观测到17条γ射线和11条新能级,能级纲图延伸到了激发能为103MeV处,在此高激发能区,能级结构仍呈现粒子组态的特性,没有发现长寿命的同质异能态.     

207Rn能级结构的实验研究

利用能量为85—95MeV的^0束流，通过^196Pt(^160，5n)^207Rn反应布居了^207Rn的高自旋态。实验进行了γ射线的激发函数、γ射线的单谱、衰变谱和γ—γ—t符合测量。建立了由17条γ射线组成的^207Rn能级纲图，并且基于实验测量的DC0系数建议了各能级的自旋值。用一个人f5/2价中子空穴与^207Rn核芯耦合定性地解释了^207Rn的低位激发态。     

奇—奇核114Pm高自旋同质异能态及其衰变纲图的研究

用高自旋同质异能态次级束流线实验装置,对¹⁴⁴Pm的高自旋同质异能态进行了快速分离,并做了γ射线的符合测量.结合γ射线激发函数和各向异性的测量结果,首次建立了奇—奇核¹⁴⁴Pm的高自旋同质异能态的衰变纲图,其中19条高自旋能级和29条γ射线是由本工作指定的.离子γ射线关联测量确定了¹⁴⁴Pm的高自旋同质异能态的半衰期大于2μs.通过系统性比较以及变形的独立粒子模型理论计算,指定了高自旋同质异能态的粒子组态可能为π(1h²_11/2d_5/2)v(1i_13/21h_9/22f_7/2),自旋宇称为J^π=27⁺,并具有形变参数为β=－0.18的扁椭球形状.     

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.     

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.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.