Acoustoelectric effect in semiconductor materials and devices

This paper reviews the studies on acoustoelectric effectin extrinsic semiconductor materials used in various scientific and othermeasurements.A historical review of earlier findings is given with specialreference to associated mechanisms.Acoustoelectric studies in solid statedevioes require further attention and the work done in this area is alsodiscussed.     

Using Dichroism to Elucidate the Nature of Magnetic Interactions in Antiferromagnetic Materials

William(familiarly known as Bill by all his colleagues) Yen's life-long scientific interest in the magnetic properties of rutile structured antiferromagnetic materials(AFMs) began with his involvement in the discovery in 1965 of the magnon sidebands of MnF2 in optical absorption[1].A basic outline of this discovery is given elsewhere in this special issue of the Chinese Journal of Luminescence[2].A narrative discussion of events leading to this discovery appears in a contribution written by Bill and Robert White for a special edition of Low Temperature Physics on Antiferromagnetism[3].A quote from that remembrance highlights a quality that remained with Bill throughout his career: "The identification of these sidebands by a pair of young students and two post-docs illustrates how serendipity,a touch of good luck and reckless youthful enthusiasm often plays a role in scientific discovery".Bill's forever youthful enthusiasm coupled with creative insights into current research questions led to numerous pioneering discoveries throughout his career.This paper reviews Bill's contributions to developing techniques to exploit dichroism to study the magnetic properties of AFMs.Bill's publications in this area span more than 30 years,from 1971 to 2004.     

Study of the efficiency of event start time determination at BESⅢ

A method to estimate the efficiency of event start time determination at BESIII is developed.This method estimates the efficiency at the event level by combining the efficiencies of various tracks(e,μ,π,K,p,γ)in a Bayesian way.Efficiencies results and the difference between data and MC at the track level are presented in this paper.For a given physics channel,event start time efficiency and systematic error can be estimated following this method.     

Photoacoustic measurement of the thermal property of condensed matter using a strong light-absorbing surface layer

By using a strong light-absorbing surface layer and front-surfaceillumination with a low power He-Ne laser(6mW),photoacousticmeasurements of the thermal effusivities of materials have been made,based on the photoacoustic theory,derived in this paper,of condensedmatter with a strong light-absorbing surface layer.This method can elimi-nate the stray light,give full play to the power of the light irradiation,and improve the signal to noise ratio.The experiment results are in goodagreement with the theoretical values.     

The effects of cubic potentials on discrete breathers in a mixed Klein－Gordon /Fermi－Pasta－Ulam chain

Nonlinearity has a crucial impact on the symmetry properties of dynamical systems. This paper studies a one-dimensional mixed Klein--Gordon/Fermi--Pasta--Ulam diatomic chain using the expanded rotating plane-wave approximation and numerical calculations to determine the effect of cubic potentials on the symmetry properties of discrete breathers in this system. The results will be very useful to researchers in the field of numerical calculations on discrete breathers.     

Studies of collisionless shockwaves using high-power laser pulses in laboratories

The remarkable experimental progress in the studies of collisionless shockwave(CS)in laboratories employing highpower lasers is briefly reviewed.The results show that CS can be generated in laser-produced plasmas due to the microturbulence associated with instabilities.CS is one of the most important astronomical phenomena.It has been found in supernova remnants(SNRs),Sun–Earth space,etc.This paper focuses on CS in ways relevant to SNRs.Laboratory astrophysics(LA),a new interdisciplinary frontier of astrophysics,plasma and laser physics,has developed rapidly in recent years.As an accessory to the astronomical observation,LA experimenters can closely study some astronomical events scaled-down to controllable phenomena.     

Partial Wave Analysis of J/ψ Decays into ρρπ

The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ →ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite complicated. In this paper, the method to use the partial wave analysis based on covariant helicity amplitude analysis to study the invariant mass spectrum of ρρπ and to find the evidence of exotic states in ρρπ spectrum is discussed. The decay amplitude for the decay sequence J/ψ→ρX, X →ρπ is given first. Then we discuss how to realize the identical particle symmetry and the isospin symmetry in the decay amplitude, which is the key point in the analysis of this channel. Then the total decay amplitude of this channel including all decay components is given. After that, how to identify the exotic states in the ρρπ spectrum is discussed. What is discussed in this paper is the theoretical basis on experimentally searching for exotic states at BEPC/BES.     

Advances in micro-perforated panel absorbers

Theoretical and experimental investigations on the performance of micro-perforated -panel absorbers are reviewed in this paper. By reviewing recent research work, this paper reveals a relationship between the maximum absorption coefficient and the limit of the absorption frequency bandwidth. It has been demonstrated that the absorption frequency bandwidth can be extended up to 3 or 4 octaves as the diameters of the micro-holes decrease. This has become possible with the development of the technologies for manufacturing micro-perforated panels, such as laser drilling, powder metallurgy, welded meshing and electro-etching to form micrometer order holes. In this paper, absorption characteristics of such absorbers in random fields and in high sound intensity are discussed both theoretically and experimentally. A new absorbing structure based on micro-perforated-panel absorbers demonstrate experimentally high sound absorption capability. This review shows that the micro-perforated-panel absorber has potentials to be one of ideal absorbing materials in the 21st century.     

Partial Wave Analysis of J/ψ Decays into ρρπ

The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ→ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite complicated. In this paper, the method to use the partial wave analysis based on covariant helicity amplitude analysis to study the invariant mass spectrum of ρπ and to find the evidence of exotic states in ρπ spectrum is discussed. The decay amplitude for the decay sequence J/ψ→ρX, X →ρπ is given first. Then we discuss how to realize the identical particle symmetry and the isospin symmetry in the decay amplitude, which is the key point in the analysis of this channel. Then the total decay amplitude of this channel including all decay components is given. After that, how to identify the exotic states in the ρπ spectrum is discussed. What is discussed in this paper is the theoretical basis on experimentally searching for exotic states at BEPC/BES.     

Partial Wave Analysis of J/ψ Decays into ρρπ

The possible place to search for exotic states in J/ψ hadronic decays is in J/ψ→ρρπ. Because of the symmetry of identical particle and the symmetry of isospin, the physical analysis on this channel is quite complicated. In this paper, the method to use the partial wave analysis based on covariant helicity amplitude analysis to study the invariant mass spectrum of ρπ and to find the evidence of exotic states in ρπ spectrum is discussed. The decay amplitude for the decay sequence J/ψ→ρX, X →ρπ is given first. Then we discuss how to realize the identical particle symmetry and the isospin symmetry in the decay amplitude, which is the key point in the analysis of this channel. Then the total decay amplitude of this channel including all decay components is given. After that, how to identify the exotic states in the ρπ spectrum is discussed. What is discussed in this paper is the theoretical basis on experimentally searching for exotic states at BEPC/BES.     

Astronomical function and date of the Taosi observatory

The Taosi site in Xiangfen County, Shanxi Province, may be the capital of the King Yao. Archeologists recently discovered a large semi-circular stamped-earth platform, II FJT1, which has a clear and definite pounded-earth central core together with a curved wall perforated by twelve gaps. The platform is said to be an ancient observatory used to determine the seasons by watching the sunrise. Each feature of II FJT1 was precisely measured and the data are reproduced in this paper. An astronomical analysis of slots E2 and E12 was carried out using the azimuths of the slots’ centerlines and the vertical angle of the mountain ridge opposite, above which the sun rises. The results show that at present the sun is close to the two slots but does not exactly enter them at summer and winter solstice sunrise. Using 14C analysis archeologists dated the site to about 2100 BC. Because of the secular change in the obliquity of the ecliptic, at that date on the summer solstice the half-risen sun would have appeared inside slot E12 just to the right of the centerline, and on the winter solstice the sun would have been exactly on the centerline of slot E2. This result provides compelling proof that II FJT1 is an ancient observatory.     

Different approaches to the study of the gravitational radiation emitted by astrophysical sources

Stars and black holes are sources of gravitational radiation in many phases of their life, and the signals they emit exhibit features that are characteristic of the generating process. Emitted since the beginning of star formation, these signals also contribute to create a stochastic background of gravitational waves. We shall show how the spectral properties of this background can be estimated in terms of the energy spectrum of each single event and of the star formation rate history, which is now deducible from astronomical observations. We shall further discuss the process of scattering of masses by stars and black holes, showing that, unlike black holes, stars emit signals that carry a clear signature of the nature of the source.     

成都金沙遗址古代陶片的PIXE和RBS分析(英文)

成都金沙遗址的年代覆盖了商代晚期至西周时期（公元前1200年—公元前650年）, 一般被认为是三星堆文化的延续。初步建立了质子激发X射线发射（PIXE）和卢瑟福背散射（RBS）实验装置, 并采用PIXE和RBS方法研究了从金沙遗址出土的部分陶片的元素组成。通过因子分析, 观察到来自不同地层的陶片的元素组成存在一定的差异, 这可能意味着制作陶器的陶土在不同时期取自不同的地点。也观察到来自不同发掘坑的陶片的元素组成没有明显的聚类现象, 这可能意味着制作不同使用用途的陶器所用的陶土是没有区别的。Jinsha Ruins Site, Chengdu, China, spanned the age from late Shang Dynasty to Western Zhou Dynasty (B.C.1200—B.C.650), was generally considered as the inheritance of Sanxingdui Culture. This paper focuses on the studies of the pottery unearthed from Jinsha. PIXE and RBS experimental setup was preliminarily established and these techniques were employed to find the elemental composition of those collected shards. From the results of factor analysis, the differences can be seen among pottery shards from different stratums, which may suggest that the clay gathered from different sites was used in different periods. The authors also found that there was no obvious assemblage phenomenon in the factor analysis among the pottery shards from different pits, this may be the evidence for “no special clay for special use”.     

The identification of comets in Chinese historical records

The historical records of astronomical phenomena may play a significant role in comet identification.Getting an accurate result is based on many factors,of which the calculation of orbital elements is the most important.This paper presents a Cross Reference method in which the perturbation of Jupiter is the only considered factor used to attempt an efficient way of comet identification with ancient Chinese historical records.In this method,the records before and after the calculated result from orbital dete...     

陕西周原遗址出土西周原始瓷工艺特征的初步研究

南方地区原始瓷出土数量较多且出土地点较为集中,从而对它的工艺和产地研究较为深入;而北方原始瓷因出土地点分布零散和数量的限制,对它的科技分析比较少。随着陕西周原遗址出土了大量原始瓷,有必要对该遗址出土的原始瓷做一个整体分析。为了探讨陕西周原遗址出土西周时期原始瓷的工艺特征,采用超景深三维视频显微系统和能量色散X射线荧光光谱分别对原始瓷胎釉微观结构和化学元素组成进行了观察与测试。显微观察可见：原始瓷胎质粗糙,胎中未熔颗粒、孔隙较多;施釉不均,釉层较为浑浊,分布较多气泡。化学组成测试结果显示：胎中Al₂O₃含量集中在11.8%～17.21%,SiO₂含量分布在75%～80.5%, K₂O含量分布在3%～7.85%;釉中CaO含量分布在11.08%～23.94%, P₂O₅含量分布在1%～3.18%、MnO含量分布在0.24%～1%,而釉中P₂O₅,MnO,K₂O含量较胎相对提高。结果分析表明：原始瓷胎料可能选用含较高钾的瓷石;釉应是添加了草木灰的钙釉;周原遗址的原始瓷工艺尚处于制瓷技术初级阶段。     

广西合浦九只岭汉墓出土石榴子石珠饰的科学分析

为探明广西合浦九只岭汉墓出土的一批紫色珠饰的材质、制作工艺和可能的原料来源,应用X射线荧光光谱、激光拉曼光谱和以及超景深三维显微系统三种分析技术科学分析了其中8枚珠饰。根据X射线荧光光谱和激光拉曼光谱分析结果,从矿物学特征上讲,这些珠饰是由石榴子石族矿物中的铝系石榴石加工而成,除一件样品属于铁铝-镁铝榴石型外,其矿物成分体系具有较高一致性,其他样品均属于富铁铝榴石型石榴子石。结合超景深数码显微系统所获取的样品加工痕迹信息以及近年考古学和科技研究成果,探讨了这批石榴子石的加工工艺和可能的来源。判断这批珠饰采用了旋磨工艺和皮囊球磨工艺两种打磨工艺,采用双钻石钻具对钻的钻孔工艺。这批铁铝榴石宝石珠饰应是由南亚或南亚经东南亚通过海上丝绸之路输入到合浦的,是汉代海上丝绸之路贸易的重要物证,对研究海上丝绸之路的历史和文化交流等具有重要的意义。     

一种大口径大非球面度天文镜面磨制新技术

主动抛光盘技术是近年来因天文望远镜的口径越来越大,焦比越来越快而发展起来的一种能够根据需要将抛光盘面实时地主动变形成偏轴非球面来磨制大口径非球面度高精度天文镜面的磨制技术。非球面表面的曲率不仅各点不一致,而且同一点的径向与切向曲率也不相同,所以经典的大的抛光盘不可能使其表面形状始终与所接触的非球面表面形状相吻合;常用的小磨盘抛光的致命缺点是解决不了高频切带,抛光效率也低。而主动抛光盘技术正好解决这些难题。与传统方法相比,它具有较高的磨削速率和较大范围内的自然平滑(无切带)。这是一种用计算机控制的磨镜技术,通过它可以像加工球面一样来加工一个深度的非球面。介绍了我国成功研制的主动抛光盘以及它在直径910mm,焦比F／2抛物面镜加工中的成功应用和加工的结果,以及此项技术将在2m以上直径天文镜面,特别是30m巨型天文光学／红外望远镜的分块子镜磨制中的应用前景。     

光学萌芽时期的科学思维与中西文明对比

围绕科学教育的目的,通识课程“众说有光”模块基于中西方光学萌芽时期的发展史实现教学设计,引导学生了解人类历史早期不同社会群体对光学基本问题从主观认识向客观理解的演变过程,探究该时期光学理论体系的发展状况,思考中西文明对科学思维形成、研究方法演变等方面的影响,并从多学科的视角了解光学发展与人类文明的联系.     

Light scattering simulation for the characterization of sintered silver nanoparticles

Light scattering is a useful tool in optical particle characterization. It can help to understand the nature of single particles as well as systems or clusters of particles; information about particle sizes, materials or shapes can be gathered. In this paper we investigate the application of light scattering studies to the analysis of a sintering process of silver nanoparticles. For this we first simulate the scattering behavior of two silver spheres. Then we assume sintering between them, leading to a single particle with a concave, peanut-like shape. We approximate this shape by a Cassini-oval. For light scattering studies we use an advanced T-matrix algorithm, the Nullfield Method with Discrete Sources. This method proved to be capable of simulating light scattering by concave particles. To make sure that the calculated data are correct we do comparative simulations using the Discrete Sources Method.