超晶格量子阱的沟道辐射及其谱分布

在经典物理框架内和偶极近似下, 导出了超晶格量子阱沟道辐射频率和辐射谱分布。指出了对于自发辐射谱分布, 存在一个普适的线型因子, 而粒子的最大辐射能量与相对论因子γ 有关, 且与γ3/2成正比。以正弦平方势为例进行了具体讨论。结果表明, 由于势阱深度和噪音的影响, 谐波数l只取少数几个值。超晶格量子阱沟道辐射只存在不多的几条谱线, 为进一步应用提供了可能。最后, 还给出了一种可能的实验方案, 讨论了如何利用弯晶把超晶格量子阱的沟道辐射改造为相干辐射。 In the frame of classical physics and the dipole approximation the radiation frequency and the spectral distribution are derived for the channeling radiation of a charged particle in a superlattice quantum well. It indicated that there is a line type factor f(ξ) suited to various cases in the spontaneous radiations spectrum. Results also show that the maximum radiation energy is proportional to γ3/2 , but the relativistic effects have double effects in the spontaneous radiation of a charged particle. The case for the sine squared potential is discussed specifically. The harmonic number can be defined as a few variable values by the effects of the potential well depth and noise. In general there is a few spectral lines in the channeling radiation spectrum for the superlattice quantum well, and possibilities are provided for further application. Finally, a possible experimental scheme is proposed, and it is discussed that how to transform the channeling radiation in the quantum well into the cohenent radiation by the bent crystal.     

Study on CYCIAE-100 radiation field and residual radioactivity

The accelerators should be properly designed to make the radiation field produced by beam loss satisfy the dose limits. The radiation field for high intensity H^－ cyclotron includes prompt radiation and residual radiation field. The induced radioactivity in accelerator components is the dominant source of occupational radiation exposure if the accelerator is well shielded. The source of radiation is the beam loss when cyclotron is operating. In this paper, the radiation field for CYCIAE-100 is calculated using Monte Carlo method and the radioactive contamination near stripping foil is studied. A method to reduce the dose equivalent rate of maintenance staff is also given.     

高能电子和正电子在晶体沟道中的辐射

介绍了高能电子和正电子在晶体中的沟道辐射,对超相对论电子和正电子在周期弯曲晶体中的相干辐射进行了分析,并提出了初步的实验设想. The channeling radiation of high energy electrons and positrons in crystals was introduced. According to the new idea proposed by A.V.Korol, the coherent radiation of ultra relativistic electrons and positrons channeled in periodically bent crystals was analyzed. The characteristics of the radiation were obtained by using classic electromagnetic theory and a tentative experimental plan for testing was suggested.     

Research on modal analysis of structural acoustic radiation using structural vibration modes and acoustic radiation modes

Modal analysis of structural acoustic radiation from a vibrating structure is discussed using structural vibration modes and acoustic radiation modes based on the quadratic form of acoustic power. The finite element method is employed for discretisizing the structure. The boundary element method and Rayleigh integral are used for modeling the acoustic fluid. It is shown that the power radiated by a single vibration mode is to increase the radiated power and the effect of modal interaction can lead to an increase or a decrease or no change in the radiated power, moreover, control of vibration modes is a good way to reduce both vibration and radiated sound as long as the influence of interaction of vibration modes on sound radiation is insignificant. Stiffeners may change mode shapes of a plate and thus change radiation efficiency of the plate‘s modes. The CHIEF method is adopted to obtain an acoustic radiation mode formulation without the nonuniqueness difficulty at critical frequencies for three-dimensional structures by using Moore-Penrose inverse. A pulsating cube is involved to verify the formulation. Good agreement is obtained between the numerical and analytical solutions. The shapes and radiation efficiencies of acoustic radiation modes of the cube are discussed. The structural acoustic control using structural vibration modes and acoustic radiation modes are compared and studied.     

Study on CYCIAE-100 radiation field and residual radioactivity

The accelerators should be properly designed to make the radiation field produced by beam loss satisfy the dose limits. The radiation field for high intensity H- cyclotron includes prompt radiation and residual radiation field. The induced radioactivity in accelerator components is the dominant source of occupational radiation exposure if the accelerator is well shielded. The source of radiation is the beam loss when cyclotron is operating. In this paper, the radiation field for CYCIAE-100 is calculated using Monte Carlo method and the radioactive contamination near stripping foil is studied. A method to reduce the dose equivalent rate of maintenance staff is also given.     

正弦平方势与沟道辐射的谱线展宽

利用曾经提出的正弦平方势解析地处理了非线性效应和偶极效应对沟道谱线宽度的影响, 解释了正电子能量在5 GeV附近的Si (110)面沟道辐射谱特征. The spectral properties of the planar channeling radiation of positron have been investigated by using Sine squared Potential. At positron energy of 5 GeV a sharp line has been explained for the planar channeling radiation in Si(110 ). It is that theoretic results are compatible to the experiments.     

Characterization of electro-acoustics impedance and its application to active noise control

Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed. Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.     

Improved method for analyzing quasi-optical launchers

An improved method for analyzing the radiation characteristic of the quasi-optical launcher is presented. The launcher is decomposed into an open-ended waveguide and a helical cut according to the proposed method. The radiation from the open-ended waveguide is obtained by using the Stratton-Chu formulation. The helical cut＇s radiation is calculated based on its current distribution, gained by several iterative computations, which helps to improve the calculation accuracy since the diffraction effect introduced by the helical cut is considered during the calculation. The proposed method is used to study different launches, and the results are compared with the existing results. Good agreement is achieved between the results obtained from our proposed method and the reported results. The present results provide an alternative for analysis and synthesis of the optical-mode converter.     

The anomalous radiation force of light on a left-handed material

This paper derives the force of the electromagnetic radiation on left-handed materials (LHMs) by a direct applica-tion of the Lorentz law of classical electrodynamics.The expressions of radiation force are given for TE-polarised and TM-polarised fields.The numerical results demonstrate that electromagnetic waves exert an inverse lateral radiation force on each edge of the beams,that is,the lateral pressure is expansive for TE-polarised beams and compressive for TM-polarised beams.The investigation of the radiation force will provide insights into the fundamental properties of LHMs and will provide to better understanding of the interaction of light with LHMs.     

Terahertz coherent transition radiation based on an ultrashort electron bunching beam

The experimental result of terahertz (THz) coherent transition radiation generated from an ultrashort electron bunching beam is reported.During this experiment,the window for THz transmission from ultrahigh vacuum to free air is tested.The compact measurement system which can simultaneously test the THz wave power and frequency is built and proofed.With the help of improved Martin-Puplett interferometer and Kramers-Krong transform,the longitudinal bunch length is measured.The results show that the peak power of THz radiation wave is more than 80 kW,and its radiation frequency is from 0.1 THz to 1.5 THz.     

Quasichanneling of ions in crystals. I. Elastic scattering of ions on atomic “chains” and planes

The scattering of quasichanneled particles on atomic chains and planes is studied by computer simulation for the crystals of chemical compounds. It is shown that quasichanneling is the specific regime of ion motion in the lattice. Its main features are: (1) a sharp increase of the backscattering probability; (2) transition of the ions from the quasichanneled component into a random one; (3) high sensitivity to the structure and the composition of the atomic “chain”; (4) dependence on the value and the direction of the atomic displacements.     

Anomalous passage of ultrarelativistic electrons in thick single crystals in axial channeling

The dynamics of ultrarelativistic axially channeled electrons in thick crystals is studied. It is revealed that a certain fraction of initial electrons have anomalously large dechanneling depths. It is shown also that the dechanneling depth in heavy and light crystals are comparable. In some cases, the number of channeled electrons can strongly increase at the expence of quasi-channeled electrons.

The problem of quasichanneling is also considered.     

辐射烧蚀CH薄膜非平衡理论计算与实验比对分析

 用一维非平衡辐射输运程序和实验提供的黑腔辐射流，对CH薄膜靶的辐射烧蚀进行了数值模拟计算。计算结果表明，非平衡的黑腔辐射场对CH薄膜靶辐射烧蚀的影响十分明显。出靶外界面的辐射流总强度、等效辐射温度随时间变化、400eV光子出界面延迟时间随靶厚度变化规律等方面的数值模拟结果与实验结果基本符合。     

辐射测量中的成像效应

明确了辐射的非成像测量和成像测量之间的差异并给出数学表述, 才能够把已经成熟的非成像辐射测量方法推广至成像测量. 本文从辐射测量的基本公式以及成像下目标微元与传感阵列像素的对应关系出发, 分别建立了关于辐射的非成像和成像测量式.根据成像面的存在不会改变辐射传输的事实, 比较非成像测量式和成像测量式后, 可得到成像效应的数学表述. 把成像效应与针孔和透镜两种成像技术结合后的分析指出: 成像效应的主因是成像光轴角, 辅因是测量天顶角; 辅因作用的大小取决于测量天顶角与发射天顶角的差异度. 关键词： 辐射测量 辐射测温 成像效应     

北京谱仪BES辐射本底水平的测定

北京谱仪BES辐射本底水平是由大厅内的辐射水平决定的.降低厅内的辐射水平是减少BES的辐射本底和提高BES探测效率和“信噪比”的重要途径.文中着重研究了谱仪厅内辐射本底的强度,来源及特点,并探讨了减少辐射的方法.     

Measurement of angular distribution of soft X‐ray radiation from thin targets in the tabletop storage ring MIRRORCLE‐20SX

The only available tabletop electron storage rings are the machines from the MIRRORCLE series. The electrons are accelerated in a microtron and injected into the storage ring. During its circulation, each electron passes through a tiny target many times, emitting a photon beam. Both the spectrum and the angular distribution of the radiation depend on the material, the thickness and the shape of the target. In this paper measured angular distributions of the radiation from several different targets in the magnetic field of the 20 MeV storage ring MIRRORCLE‐20SX are presented. The detector comprises a 3 mm × 3 mm × 8.5 µm plastic scintillator (PS) coupled to a photomultiplier by a bundle of optical fibers. The output of the photomultiplier is digitized by an IF converter. This detector is sensitive mostly to soft X‐ray radiation, and its PS is moved by a mechanical system in a plane perpendicular to the radiation axis. The measured angular distributions for Mo and Sn targets contain an annulus which is attributed to transition radiation. The angular distributions for Al, carbon nanotube and diamond‐like carbon (DLC) targets show some suppression of the radiation along the magnetic field. This is the first evidence of observation of the angular distribution of synchrotron Cherenkov radiation, which represents Cherenkov radiation in a magnetic field. The power radiated from the DLC target is estimated.     

γ脉宽对电子器件瞬时辐照效应的影响

 采用了2种γ脉冲辐射源,在脉冲宽度分别约为20,50,150 ns,剂量率为10⁶～10⁹ Gy(Si)·s^-1下,对5种不同类型的电子器件进行了辐照试验并对其辐照响应进行了分析,比较了不同脉冲宽度条件下辐照响应的差异。实验结果表明：脉冲宽度是影响瞬时辐照效应的重要因素,γ脉冲宽度越宽,辐照响应越强,分离器件比集成电路受脉宽的影响更明显。     

核科学百年讲座第九讲电离辐射与人类生活及环境

文章介绍了在人类生存环境中与一般公众生活密切相关的各种电离辐射的来源、影响因素、变化规律、对公众所产生的照射剂量以及有可能导致的生物效应，特别是对天然辐射照射做了详细和系统的叙述分析，同时对人类实践活动产生的人工辐射和医学照射也进行了介绍和评述．文章旨在引导人们正确认识放射性这一自然现象，在消除核恐怖心理的同时，对其在应用中的安全性予以足够的重视。     

黑体辐射中两类粒子的辐射规律

考虑到相对论效应,采用量子统计的方法,得到了满足Bose-Einstein统计分布和Fermi-Dirac统计分布的两类粒子的黑体辐射公式（包括Planck黑体辐射公式）．发现辐射谱不仅与黑体的辐射温度有关,还与辐射粒子的能量、化学势和种类有关．辐射强度与辐射粒子的能量、静质量、简并因子有关。     

辐射阻尼对带电粒子运动的影响

探讨了带电粒子的初速和磁场方向垂直，并考虑其受到辐射阻尼力时的运动方程和运动轨道，同时探讨其辐射功率。