CSRe团簇内靶温度闭环控制器设计；Design of Closed Loop Temperature Controller for CSRe Internal Target System

介绍了国家重大科学工程项目——兰州重离子加速器冷却存储环(HIRFL-CSR)的实验环(CSRe)团簇内靶温度闭环控制器的设计。该控制器给气体喷嘴处测温电阻提供长时间稳定度为0.1%的1mA恒定电流,通过12位ADC得到喷嘴温度,并通过混合信号处理器MSP430F149来实现制冷/加热闭环操作。在多种不同实验气体的情况下,该控制器的温度控制精度小于0.5K。目前,该控制器在现场工作良好。

CSRe储存环动力学孔径研究(英文)；Dynamic Aperture Studies for CSRe Storage Ring

动力学孔径对环形加速器,尤其是现代的储存环,起着越来越重要的作用。采用MAD程序研究了兰州重离子加速器实验环(CSRe)的动力学孔径。通过对比几种情况下的模拟结果,发现六极铁和二极铁的高阶场对束流的动力学孔径影响较大,使CSRe的动力学孔径减小,但减小后的动力学孔径也远大于该环的物理孔径。因此,束流可以长期、稳定的存在。

A high performance Time-of-Flight detector applied to isochronous mass measurement at CSRe

A high performance Time-of-Flight detector has been designed and constructed for isochronous mass spectrometry at the experimental Cooler Storage Ring (CSRe) The detector has been successfully used in an experiment to measure the masses of the N approximate to Z approximate to 33 nuclides near the proton drip-line Of particular interest is the mass of As-65 A maximum detection efficiency of 70% and a time resolution of 118 +/- 8 Ps (FWHM) have been achieved in the experiment The dependence of detection efficiency and signal average pulse height (APH) on atomic number Z has been studied The potential of APH for Z identification has been discussed (C) 2010 Elsevier B V All rights reserved

Commissioning of electron cooling in CSRe

The 400 MeV/u C-12(6+) ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe. The momentum cooling time was estimated near 15 s. The cooling force was measured in the cases of different electron beam profiles, and the different angles between the ion beam and electron beam. The lifetime of the ion beam in CSRe was over 80 h. The dispersion in the cooling section was confirmed as positive close to zero. The beam sizes before cooling and after cooling were measured by the moving screen. The beam diameter after cooling was about 1 mm. The bunch length was measured with the help of the signals from the beam position monitor. The diffusion was studied in the absence of the electron beam.

Secondary electron time detector for mass measurements at CSRe

The Isochronous Mass Spectrometry is a high accurate mass spectrometer. A secondary electrons time detector has been developed and used for mass measurements. Secondary electrons from a thin carbon foil are accelerated by ail electric field and deflected 180 degrees by a magnetic field onto a micro-channel plate. The time detector has been tested with alpha particles and a time resolution of 197 ps (FWHM) was obtained in the laboratory. A mass resolution around 8 x 10(-6) For Delta m/m was achieved by using this time detector in a pilot mass measurement experiment.

CSRe Schottky 质量谱仪研究

HIRFL-CSR 联合Schottky信号诊断的方法为高精度测量离子质量提供了一个新的途径，本论文研究了CSRe Schottky 质量谱仪的原理,电子冷却模式下进行质量测量时的磁铁设置，各种系统误差以及能达到的精度估计。首先研究了CSRe的线性lattice中动量压缩因子对动量色散的依赖，以及动量压缩因子的高阶项的存在会对常用的线性质量刻度造成多大的系统误差。讨论了利用六级铁的适当设置减小这种系统误差的方法，给出利用MAD程序的模拟的CSRe六级铁的适当设置数值以及动量压缩因子对动量分散的依赖曲线。接着详细讨论了其他的几种主要的系统误差以及消除方法，给出了一种新的准确度更高的非线性的质量刻度方法。最后研究了电子冷却模式下CSRe Schottky质量谱仪精度的决定因素，调研了在CSRe上进行对190Ir和188Os可行性以及估计了在现有条件下，能够达到的精度,探讨了进一步提高质量刻度的精度和准确度的实现途径

CSRe束流动力学研究

非线性动力学对于环形加速器，尤其是对现代新型的加速器来说，起着越来越重要的作用。非线性力的引入使得束流在真空管道中的稳定性大大降低，对物理实验产生较大的影响。所以对束流动力学尤其是非线性动力学的研究已成为加速器研究中的一个必要的、重要的课题。 本文首先对加速器物理的基础知识和兰州重离子加速器冷却储存环及其实验环（HIRFL-CSRe）做了一定的介绍。然后给出了非线性力存在时的动力学孔径的理解和此时动力学孔径的多种研究方法。 接着本论文对束流的共振情况做了推导和描述，用映射的观点，通过Normal Form这一数学工具研究了CSRe的非线性动力学。然后用加速器常用的软件（COSY INFINITY）研究了HIRFL-CSRe在各种状态下由于高阶场误差带来的非线性力对各阶共振力的影响。 最后，也是本文的核心部分。用MAD程序研究了CSRe横向动力学。对CSRe色品进行了校正，并计算了色品六极铁对CSRe Lattice的影响。对CSRe理想Lattice的动力学孔径进行了计算，然后根据实际测磁数据计算了CSRe在有二极铁和四极铁高阶误差等多种情况下的动力学孔径，最后通过实际实验时的束流的各种参数的测量说明了理论计算和实际情况一致，强度和稳定性都能够满足物理实验的要求。 本论文对CSRe系统的运行和CSRe各项实验有着一定的实际意义

CSRe横向动力学研究

随着现代加速器向高能、强流、长寿命束流方向的发展，非线性动力学已经成为现代加速器研究中一个非常重要的课题。非线性力的引入使得束流在真空管道中的稳定性大大降低，对物理实验产生较大的影响。因此束流动力学尤其是非线性动力学，在现代加速器的研究中已经起着日益重要的作用。 本文首先对束流横向动力学的基础理论进行了介绍。然后通过实际的测量数据，利用MAD程序对CSRe的二极铁离散性误差和四极铁的安装误差所引起的闭轨畸变进行了模拟和校正，并比较了不同的校正方案，将CSRe的闭轨畸变均方根校正到了0.1mm以下。 接着本文介绍了动力学孔径的概念，并给出了非线性力存在时的动力学孔径的理解和此时动力学孔径的多种研究方法。 最后，本文利用MAD程序对CSRe的横向动力学进行了研究。对CSRe色品进行了校正，并计算了色品六极铁对CSRe Lattice的影响，分析了CSRe的色差效应。对CSRe理想Lattice的动力学孔径进行了跟踪模拟。 并对粒子能量为400MeV和600MeV时，存在二极铁和四极铁高阶场误差情况下的动力学孔径进行了跟踪研究。

HIRFL-CSRe的团簇内靶建设

HIRFL-CSRe的内靶有两种工作模式：团簇靶模式和原子束极化靶模式，团簇靶用于为实验环内的物理实验提供厚度为1011-1013 atoms／cmZ的氮、J隋性气体和甲烷等小分子的气体薄靶。本工作主要是进行兰州重离子冷却储存环实验环团簇内靶的建设，完成了团簇内靶的安装和准直、真空测试、温度测试、流量刻度、抽速刻度以及运行稳定性测试等工作，并去得了一些结果。总体来看，除轻气体外，团簇内靶的整体指标（靶厚和真空）达到了设计要求，对轻气体尚需进行改进。尚需优化的两个方面：1）解决喷嘴堵塞问题。除了液氮之外，采用其它靶气体源都出现了喷嘴堵塞现象，这个问题直接影响到团簇靶的正常运行；2）对于较轻的气体，如Ne和H：，获得的靶厚较小或者没有，而且各级的真空较差。经过分析，认为喷嘴堵塞的原因有两个方面，一是靶气体本身含有杂质，二是外界杂质。由于喷嘴级的分子泵对于轻气体没有足够的抽速和压缩比，不能将残余轻气体及时抽走，从而导致真空较差，当还没有获得有效靶厚时，团簇源第一级真空腔体的气压已经超过分子泵的工作气压了，因而对H：未获得有效靶厚。对于以上两个问题，我们采取了两项措施：1）设计加工了气体纯化装置，采用制冷与过滤相结合的方法对充入系统的气体进行预先纯化，该装置己完成加工，即将进行实验；2）优化抽气系统，增大团簇源第一级对轻气体的抽速和压缩比。

Embodied energy in cement stabilised rammed earth walls

Rammed earth walls are low carbon emission and energy efficient alternatives to load bearing walls. Large numbers of rammed earth buildings have been constructed in the recent past across the globe. This paper is focused on embodied energy in cement stabilised rammed earth (CSRE) walls. Influence of soil grading, density and cement content on compaction energy input has been monitored. A comparison between energy content of cement and energy in transportation of materials, with that of the actual energy input during rammed earth compaction in the actual field conditions and the laboratory has been made. Major conclusions of the investigations are (a) compaction energy increases with increase in clay fraction of the soil mix and it is sensitive to density of the CSRE wall, (b) compaction energy varies between 0.033 MJ/m(3) and 0.36 MJ/m(3) for the range of densities and cement contents attempted, (c) energy expenditure in the compaction process is negligible when compared to energy content of the cement and (d) total embodied energy in CSRE walls increases linearly with the increase in cement content and is in the range of 0.4-0.5 GJ/m(3) for cement content in the rage of 6-8%. (C) 2009 Elsevier B.V. All rights reserved.

Cement stabilised rammed earth. Part A: compaction characteristics and physical properties of compacted cement stabilised soils

Rammed earth is used for load bearing walls of buildings and there is growing interest in this low carbon building material. This paper is focused on understanding the compaction characteristics and physical properties of compacted cement stabilised soil mixtures and cement stabilised rammed earth (CSRE). This experimental study addresses (a) influence of soil composition, cement content, time lag on compaction characteristics of stabilised soils and CSRE and (b) effect of moulding water content and density on compressive strength and water absorption of compacted cement stabilised soil mixes. Salient conclusions of the study are (a) compaction characteristics of soils are not affected by the addition of cement, (b) there is 50% fall in strength of CSRE for 10 h time lag, (c) compressive strength of compacted cement stabilised soil increases with increase in density irrespective of moulding moisture content and cement content, and (d) compressive strength increases with the increase in moulding water content and compaction of CSRE on the wet side of OMC is beneficial in terms of strength.

Cement stabilised rammed earth. Part B: compressive strength and stress-strain characteristics

Strength and behaviour of cement stabilised rammed earth (CSRE) is a scantily explored area. The present study is focused on the strength and elastic properties of CSRE. Characteristics of CSRE are influenced by soil composition, density of rammed earth, cement and moisture content. The study is focused on examining (a) role of clay content of the soil on strength of CSRE and arriving at optimum clay fraction of the soil mix, (b) influence of moisture content, cement content and density on strength and (c) stress-strain relationships and elastic properties for CSRE. Major conclusions are (a) there is considerable difference between dry and wet compressive strength of CSRE and the wet to dry strength ratio depends upon the clay fraction of soil mix and cement content, (b) optimum clay fraction yielding maximum compressive strength for CSRE is about 16%, (c) strength of CSRE is highly sensitive to density and for a 20% increase in density the strength increases by 300-500% and (d) in dry state the ultimate strain at failure for CSRE is as high as 1.5%, which is unusual for brittle materials.

Structural Behavior of Story-High Cement-Stabilized Rammed-Earth Walls under Compression

A rammed-earth wall is a monolithic construction made by compacting processed soil in progressive layers in a rigid formwork. There is a growing interest in using this low-embodied-carbon building material in buildings. The paper investigates the strength and structural behavior of story-high cement-stabilized rammed-earth (CSRE) walls, reviews literature on the strength of CSRE, and discusses results of the compressive strength of CSRE prisms, wallettes, and story-high walls. The strength of the story-high wall was compared with the strength of wallettes and prisms. There is a nearly 30% reduction in strength as the height-to-thickness ratio increases from about 5 to 20. The ultimate compressive strength of CSRE walls predicted using the tangent modulus theory is in close agreement with the experimental values. The shear failures noticed in the story-high walls resemble the shear failures of short-height prism and wallette specimens. The paper ends with a discussion of structural design and characteristic compressive strength of CSRE walls. DOI: 10.1061/(ASCE)MT.1943-5533.0000155. (C) 2011 American Society of Civil Engineers.

Role of clay content and moisture on characteristics of cement stabilised rammed earth

Rammed earth is an energy efficient and low carbon emission alternative for load bearing walls. This paper attempts to examine the influence of clay content and moisture content on the compressive strength of cement stabilised rammed earth (CSRE) through experimental investigations. Compressive strength of CSRE prisms was monitored both in dry and wet (saturated) conditions. Major conclusions of the study are:(a) Optimum clay content for maximum compressive strength is about 16%, (b) the strength of CSRE is sensitive to the moisture content at the time of testing, (c) Strength in saturated condition is less than half of the dry strength and (d) Water absorption (saturated water content) increases as the clay content of the soil mix increases and it is in the range of 12 to 16% for the CRSE prisms with 8% cement.