光纤通信系统中的非线性效应研究

文章介绍了光纤通信系统中的受激布里渊散射（SBS）、四波混频（FWM）效应和自相位调制（SPM）效应这几种重要的非线性效应,分析了其产生机理及在实际应用中对系统性能的影响。从几种非线性效应的基本原理出发,采用理论分析与模拟计算相结合的方法,研究了影响几种非线性效应的主要因素,并给出了相应的抑制消除方法

Measurements of (59)~Ni with Accelerator Mass Spectrometry

长寿命放射性核素59 nI在核物理与天体物理、放射性废物管理、陨石与宇宙射线研究、生物医学示踪等方面有着广泛的应用前景。加速器质谱技术(AMS)是实现59 nI高灵敏测量的最佳方法,59 nI-AMS测量的关键问题在于排除同量异位素59 CO的干扰。本工作利用中国原子能科学研究院HI-13大型串列加速器能量高,Q3d磁谱仪能量分辨高、色散大等特点,采用化学分离技术排除59 CO,以氯化镍作为靶物质,建立了59 nI-AMS的高灵敏测量方法,并对一系列标准样品和空白样品进行测量。结果表明,此方法有效降低了59 CO的干扰,空白样品中59 nI/nI的本底水平低于5x10-13,满足实际样品的测量需要。The long lived radioisotope of 59 Ni has wide application in many research fields,such as nuclear physics and astrophysics,the management of radioactive waste,biomedical tracer and so on.In order to carry out the applications based on 59 Ni,the method of the accelerator mass spectrometry(AMS)was developed into the best way to measure 59 Ni with high sensitivity.Interfering isobars are the main problem for 59 Ni measurement with AMS.Based on the HI-13tandem accelerator at the China Institute of Atomic Energy,high precision Q3Ddetection system and chemical separation technology,the interfering isobar of59Co is greatly eliminated.59 Ni-AMS highly sensitive measurement method is established with NiCl2as the target substance.A series of laboratory standard samples and blank sample were measured to check the performance of 59 Ni measurement.The results show that the 59Co can be excluded clearly,and the measurement sensitivity of about 5×10-13 for59 Ni/Ni is obtained based on the measurement of the blank sample,which can be used in the measurement of actual samples.国家自然科学基金(11175266)资

Measurement of ~(129)I Concentration in Air Particle Samples by AMS

建立了通过制备大气颗粒物中碘样品并采用加速器质谱(AMS)测量颗粒物样品中129I浓度的方法。采用此方法对日本福岛核电站泄漏事故期间北京大气颗粒物样品进行了129I测量,以此探讨129I在环境监测中的作用。北京地区大气颗粒物129I的测量结果显示,2011年3月26日的大气颗粒物中129I浓度已高于正常本底值的数倍,据推测这部分129I来源于福岛核电站泄漏事故。129I是重要的核裂变产物,其来源具有特殊性,较长的半衰期使其在核反应堆中长期积累,核泄漏早期存在区域环境高浓度129I现象,所以129I-AMS测量在辐射安全及应急监测方面具有潜在优势。A method to measure the 129 I concentration in air particle samples using accelerator mass spectrometry(AMS)was developed,together with the preparation of AgI target of air particle.At the same time,for the radiation monitoring use,the measurement of 129 I during the accident of Fukushima Nuclear Power Plant(FNPP)with the AMS facility at the China Institute of Atomic Energy(CIAE)was discussed.The results show that early on March 26,2011,129 I derived from FNPP accident had arrived and the 129 I concentration in air particle increased greatly relative to the backgroundvalue.Due to the long half life of 129 I and its accumulation in the NPP,the event of regional high 129 I concentration occurs in the early stage of the nuclear leakage,consequently,and the 129I-AMS measurement has great potential to be applied for radiation safety and emergency monitoring.国家自然科学基金资助项目(11075221

Study on AMS Measurement of ~(79)Se

测定79SE时由于79SE尚无标准样品,需要建立79SE/SE(79SE、SE原子个数比,余同)的AMS测量方法。在79SE/SE的绝对测定中,为尽可能避免测量SE的同位素之间的差异,通常利用探测器测量79SE离子,本文用法拉第筒对78SE和80SE进行测量,但这造成两个测量系统之间的系统误差。为避免这种系统误差,利用同一探测器测定79SE、78SE和80SE。考虑到78SE和80 SE的计数率非常高,在CIAE-AMS系统中的静电分析器前和靶室内安装衰减片以降低78SE和80SE的计数率。实验结果表明:通过两个衰减片的衰减作用,能将78SE和80SE的束流降低到半导体探测器的检测范围内,实现了样品中79SE/SE的绝对测定,得到79SE/SE为(2.08±0.10)x10-7,为准确测定79SE半衰期奠定了基础。As there is no 79Se standard sample for measurement of 79Se,the characterizations of 79Se are conducted by isotope ratio of 78Se/Se or 80Se/Se since the abundances of78Se and 80Se are well known.However,beams of 78Se and 80Se both exceed the upper limit of semiconductor detector resulting in measurement failure.As a result,attenuators were introduced into the CIAE-AMS system with the aim to measure the 79Se.The results indicate that the beam of 78Se and 80Se is decreased into the detecting range of semiconductor detector by two attenuators,which would improve measurement sensitiv-ity and efficiency significantly.In addition,the uncertainty of measurement is reduced greatly and it lays the foundation for the accuracy measurement of the half life of 79Se.国家自然科学基金资助项目(10805010;41166002;11025313;11175266); 广西自然科学基金资助项目(2011GXNSFC018016;2012GXNSFFA060005

Preliminary Study of ~(41)Ca-AMS Measurement in Rock Samples

41CA在核天体物理及地质年代学方面可能具有较高的应用价值。为测量天然岩石样品中41 CA的本底水平,探讨了41CA-AMS测量中岩石样品的CAf2制备,提出了二次氟化的制备方法。在此基础上,通过对导电介质与靶锥的改进,设计了一种提高CAf-3束流引出强度的方案。该方案可有效提高CAf-3束流引出强度。实验结果表明,天然岩石样品中41CA/40CA(41CA、40CA原子个数比)的本底水平低于8x10-14。Perhaps the value of 41Ca applications in nuclear astrophysics and geochronology is high.The CaF2preparation of rock samples was investigated to measure the background level of 41Ca in the natural rock samples by AMS.A preparation method of secondary fluorination was proposed by some physical and chemical processes.On this basis,aprogram to improve CaF-3beam intensity was designed by improving conductive medium and target cone.This sample preparation program can effectively improve the beam intensity of CaF-3.The experimental results show that with these settings the41Ca/40Ca background level of rock samples is less than 8×10-14.国家自然科学基金资助项目(11265005); 广西自然科学基金资助项目(2012GXNSFBA053001

Preparation and Accelerator Mass Spectrometry Determination of --(53)Mn/--(55)Mn Standard Reference Material

宇宙成因核素53 Mn是一种非常理想的地质定年工具。近年来,随着加速器质谱(AMS)技术的不断发展,53 Mn的高灵敏测量成为可能。本工作介绍了53 Mn/55 Mn的系列实验室标准样品的制备以及AMS测量,结果表明:53 Mn/55 Mn的测量值与标称值在误差范围内比较吻合且呈现良好的线性关系,中国原子能科学研究院的AMS系统对53 Mn的测量灵敏度可以达到10-14。The cosmogenic isotope 53Mn is a very useful tool for geochronological dating.In recent years,with the development of AMS method,the high sensitivity mearsurment for 53Mn becomes advisable.High energy is required to remove the interference of 53Cr in the AMS measurement of 53Mn,only few AMS laboratories with high terminal voltage satisfy the condition in the world by now.In this paper,the preparation of 53Mn/55Mn laboratory standard's series and the measurement with AMS method are introduced.In order to reduce the interference of 53Cr efficiently,ΔE-Q3D method was used in AMS measurement of 53Mn at China Institute of Atomic Energy(CIAE) based on the HI-13 Tandem Accelerator and the large Q3D magnetic mass spectrometer.The results show that the measured values are in good agreement with their nominal values and the linear relationship between them is excellent.The mearsurment sensitivity of 10-14 for 53Mn/55Mn ratio can be achieved by the AMS system at China Institute of Atomic Energy(CIAE).国家自然科学基金项目(11075221)资

AMS Measurement Technology for (182)Hf

为实现对182 Hf岩石样品的AMS精确测量,基于HI-13串列加速器对测量技术和方法等进行了系统的改进,主要包括:182 Hf空白样品的制备、偏置束流的同时监测技术、加速器系统稳定性检验、交替测量方案的实施、182 W扣除方法的改进、模拟样品测量检验、岩石样品测量检验及测量结果可信度检验等。实验结果表明,对于1x10-10(182 Hf/180 Hf)水平的模拟样品,测量结果的相对不确定度约为12%,基本达到岩石样品的测量要求。岩石样品的测量不确定度较大,主要原因是岩石样品中W的含量较高。In order to improve the accuracy of AMS measurement for 182Hf/180Hf,a series of improvement and innovations of measurement technique and method were taken,such as chemical synthesis of 182Hf free samples,technique of monitoring off-axis current simultaneously,testing the stability of accelerator system,performing the alternate measurement,modified deduction method of 182W,testing the measurement method with simulated samples and real rock samples,and testing the reliability of measurement results.The experimental results show that the relative uncertainty is about 12% for the simulated samples to the order of 1×10-10(182Hf/180Hf),which satisfies the requirement of measurements for real rock samples.The reason of big uncertainty with the rock sample mainly lies in the high content of W in the rock sample