康普顿背散射技术对贮存环电子束诊断及其应用-II贮存环电子束的极化度测量

简单介绍以激光 电子康普顿背散射原理为基础建立的康普顿背散射极化仪, 采用它能实时、 非破坏性地监测电子束的极化. 该项工作可作为上海激光电子γ源（SLEGS）低能γ束应用研究的内容之一. The Compton backscattering polarimeter is described briefly on the basis of the principle of Compton backscattering in this paper. The polarization of the electron beam can be measured and monitored on time and nondestructively. The project will be one of applications of low energy γ ray beam of SLEGS.     

利用BEPC建造极化γ射线光源

介绍利用北京正负电子对撞机的强流高亮度电子束与偏振强激光的康普顿背散射产生高能、高亮度、单色、极化γ射线束的特性和它的应用.     

基于同步辐射加速器的康普顿背散射γ射线源(Ⅰ)产生MeV量级γ光子的数值计算

提出在筹建的上海同步辐射装置上建造一条MeV量级γ射线束及应用站,采用μm波长的红外(或远红外)激光与储存环中3.5GeV电子束进行康普顿背散射,从而获得能区为1—25MeV的康普顿背散射γ光子束,该光子束具有高强度、高极化度(线和圆极化)、准单色、方向性好的优点,可以广泛地应用于核物理和核天体物理基础研究及相关的应用研究领域.介绍了康普顿背散射的基本原理,并结合储存环参数给出了光子束性能的数值计算结果.     

康普顿背散射技术对贮存环电子束诊断及其应用——I电子束能量的精确测量及光学标准实验站

简单叙述了采用康普顿背散射技术精确测量电子束能量的技术,并指出建立辐射标准实验站对精确电子束能量测量的需求. The technique to measure the electron beam energy accurately with Compton backscattering technique is introduced and requirements for the experimental stations of radiometry are also described in the paper.     

康普顿背散射技术对贮存环电子束诊断及其应用——I电子束能量的精确测量及光学标准实验站

简单叙述了采用康普顿背散射技术精确测量电子束能量的技术,并指出建立辐射标准实验站对精确电子束能量测量的需求. The technique to measure the electron beam energy accurately with Compton backscattering technique is introduced and requirements for the experimental stations of radiometry are also described in the paper.     

基于同步辐射加速器的康普顿背散射γ射线源——（I）产生MeV量级γ光子的数值计算

提出在筹建的上海同步辐射装置上建造一条MeV量级γ射线束及应用站，采用μm波长的红外（或远红外）激光与储存环中3．5GeV电子束进行康普顿背散射，从而获得能区为1－25MeV的康普顿背散射γ光子束，该光子束具有高强度、高极化度（线和圆极化）、准单色、方向性好的优点，可以广泛地应用于核物理和核天体物理基础研究及相关的应用研究领域。介绍了康普顿背散射的基本原理，并结合储存环参数给出了光子束性能的数值计算结果。     

强激光驱动高能极化正负电子束与偏振伽马射线的研究进展

高能自旋极化正负电子束与偏振伽马射线在高能物理、实验室天体物理与核物理等领域有十分重要的应用.近年来随着超短超强激光脉冲技术的快速发展,利用强激光与物质相互作用的非线性康普顿散射和多光子Breit-Wheeler过程为制备高极化度、高束流密度的高能极化粒子束提供了新的可能.本文对基于强激光产生高能极化正负电子束与偏振伽马射线的研究成果进行简要回顾,并介绍了这些方法的基本物理原理和主要结果.     

基于同步辐射加速器的康普顿背散射γ射线源(Ⅱ)产生亚GeV量级γ光子的数值计算

提出在筹建的上海同步辐射装置上建造一条亚GeV量级γ束线站,采用nm波长的紫外激光与储存环中3.5GeV电子束进行康普顿背散射,从而获得能区为300—870MeV的γ光子束.该光子束具有高强度、高极化度(线和圆极化)、准单色、方向性好的优点.文中结合储存环参数给出了光子束性能的数值结果,并探讨了相互作用区和标记位置的选择方案.     

高能电子束流引发的横向极化气体氢靶共振退极化研究

对于HERMES横向极化气体氢靶, 高能电子束流所激发的高频磁场会引发共振退极化. 本文就该极化度下降的产生机制进行研究, 并给出σ₂₄共振点发生位置的测量结果, 并且将极化靶磁场的强度稳定在远离共振点处, 挽回了数据获取时极化度近3%的共振损失.     

利用FEL康普顿背散射实现对NSRL辐射波段的扩展

 针对NSRL同步辐射光源不能开展硬X射线领域实验研究的缺点,提出了利用FEL康普顿背散射产生高亮度极化的硬X射线,并利用FEL波长可调的特点来连续调节硬X射线的波长。同时还针对NSRL光源的参数,提出了一个初步可行的远红外FEL参数和背散射工作方式,并给出了理论结果。     

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.     

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.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.