Experiments and modification on electron cyclotron resonance ion sources at the Institute of Modern Physics

Uranium ion beams were produced from electron cyclotron resonance (ECR) ion sources by sputtering method this year at the Institute of Modern Physics. At first, we chose the Lanzhou ECR No. 3 ion source to implement the production experiment of U ion beams. Finally, 11 e mu A of U28+, 5 e mu A of U32+, and 1.5 e mu A of U35+ were obtained. A U26+ ion beam produced by the LECR2 ion source was accelerated successfully by the cyclotron. This means that the Heavy Ion Research Facility in Lanzhou (HIRFL) has accomplished the acceleration of the ion beam of the heaviest element according to the designed parameters. The Lanzhou ECR ion source No. 2 (LECR2), which was built in 1997, has served the HIRFL for eight years and needed to be upgraded to provide more intense high charge state ion beams for HIRFL cooling storage ring. We started the upgrading project of LECR2 last year, and the modified design just has been finished. (c) 2006 American Institute of Physics.

HIRFL today

HIRFL was upgraded from beginning 2000. Besides of researches on nuclear physics, atomic physics, irradiative material and biology, the cancer therapy by heavy ion and hadron physics are being developing. The injector system of SFC+SSC can provide all ions from proton to uranium with higher intensity. The Cooling Storage Ring (CSR) has accelerated beams successful. The ions C-12(6+), Ar-36(18+), Xe-129(27+) have been accelerated up 1000MeV/u, 235MeV/u with about 10(9)similar to 10(8) ions per spill respectively. The beam momentum dispersion was measured from 4x10(-3) to 2x10(-4) after cooling by the electron cooler or similar to 4x10(-4) after accelerated to 1000MeV/u without cooling. In order to improve the nuclear structure and heavy isotope research in SFC+SSC energy domain, A Wien filter was added in front of RIBLL and gas was filled in first section of RIBLL; a new spectrometry SHANS has being installed. Presently, there are two starting version experimental setups at CSR.

Beam matching between SFC and SSC

The beam matching status between the two isochronous cyclotrons in the Heavy Ion Research Facility at the Lanzhou-Cooling Storage Ring (HIRFL-CSR) is described. Several methods which can be used to accomplish 100% matching are proposed. By comparing of them, the best method is determined. The advantage due to this method is discussed.

The equation of state study in UU collisions at CSR, Lanzhou

The cooling storage ring, to be built at Lanzhou, will be able to deliver heavy ion beams up to uranium up to 0.52 GeV/u. It is expected to make considerable contribution to nuclear EOS study in the high net baryon-density region. With a relativistic transport model, we performed simulations for U+U collisions with different orientations. It is shown that by combining the forward neutron multiplicity and an event-wise elliptic flow selection, it is possible to identify the tip - tip and body - body head-on collisions. The effective identification of these two extreme configurations will allow us to study the EOS at the highest baryon density in the U+U collisions.

Measurement of neutron flow with the external target experimental device on CSR

With the construction of the neutron detection wall at the external target position on Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring (HIRFL-CSR), it will be possible to detect high energy neutron. A BUU model is applied to simulate the flow in both symmetric (Ni+Ni, Pb+Pb) and asymmetric(Pb+Ni) systems. It is shown that at above several hundreds MeV/u, the flow signals are very obvious and depend clearly on the centrality of the collisions. Based on the products in the forward angle less than 20 degrees, the simulation also reveals that the determination of the reaction plane and the selection of the impact parameter, both of which are essential in the flow measurement, are well implemented. The double event and its influence on the determination of the neutron flow are also simulated.

General design of the CSR project in IMP

CSR, a new accelerator project under the construction. to upgrade the existing heavy ion cyclotron system in Lanzhou, is a double cooling-storage-ring system. It consists of a main ring and an experimental ring. The heavy ion beams from the cyclotron system will be accumulated and accelerated first in the main ring, then extracted to produce radioactive ion beams or high-Z beams, and finally to be send to the second ring for internal-target experiments.

Development of the lanzhou heavy ion linac

The heavy ion linac in Lanzhou is designed as a future injector for the Cooling Storage Ring (CSR). In order to keep the total machine within 40 meters, the IH (Interdigital H-type) structure is adopted for its higher acceleration gradient compared with the traditional DTL structure. The designed minimum charge over mass ratio is 1/6, the output energy is 16MeV/u and the beam current is 1A.mu A. The RFQ and the first DTL tank will work at 100MHz, and the other DTL tanks will work at the double frequency. The design criteria, main parameters and the detailed beam dynamic design are introduced in this paper.

The stripper design and test at HIRFL-CSR

Charge stripping is employed to produce multi-charged ions for injecting the cooling storage ring After penetrating through the carbon foil, the widened distribution of ion charge states poses a limit to the ion injection Therefore, the carbon foil plays a key role in the charge snipping injection In this paper, foul strippers for Heavy Ion Research Facility at Lanzhou (HIRFL) and Cooling Sun age Ring (CSR) are introduced The charge state distribution of the stripped ions is measured and the stripping efficiency of the foils is investigated The experimental results are consistent with the theoretical values

Study of a magnetic alloy-loaded RF cavity for bunch compression at the CSR

The Heavy Ion Research Facility and Cooling Storage Ring (HIRFL-CSR) accelerator in Lanzhou offers a unique possibility for the generation of high density and short pulse heavy ion beams by non-adiabatic bunch compression longitudinally, which is implemented by a fast jump of the RF-voltage amplitude. For this purpose, an RF cavity with high electric field gradient loaded with Magnetic Alloy cores has been developed. The results show that the resonant frequency range of the single-gap RF cavity is from 1.13 MHz to 1.42 MHz, and a maximum RF voltage of 40 kV with a total length of 100 cm can be obtained, which can be used to compress heavy ion beams of U-238(72+) with 250 MeV/u from the initial bunch length of 200 ns to 50 ns with the coaction of the two single-gap RF cavity mentioned above.

CSR真空控制系统的研究

本论文主要解决CSR真空系统的控制实现与连锁保护问题。 HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程。为了保证CSR正常运行，超高真空系统的平均真空度必须达到6×10-9Pa，超高的真空度来之不易，CSR上任何一处真空设备发生故障，就会破坏真空度，所以CSR必须具有响应速度快、安全可靠，稳定性好的真空控制与连锁保护系统。 HIRFL-CSR真空设备有离子泵电源、分子泵、钛升华泵、阀门、真空计等。分子泵只在粗抽时使用，钛升华泵为间歇升华，因此不需要监控。需要显示和控制的设备为离子泵电源、真空计和真空阀门。通过对CSR上每个真空计的真空度数据的监测和真空阀门状态的采集，一旦真空度降低到一定阈值，立即关闭相应位置阀门（保护真空）,并给出故障报警，从而实现真空系统的连锁保护。 真空控制系统以嵌入式处理器ARM、复杂可编程逻辑器件CPLD和微控制器MSP430为核心，实现了远程数据采集、数据显示和自动控制等功能。本系统可以进行现场监控与调试，也可以通过集成的100Mbps以太网接口电路进行远程监测与控制，CSR上各处真空度和真空阀门状态自动传送到中央控制中心，中控中心也可以发送命令查询当前真空设备状态和各种读数。 本文主要介绍了基于ARM、CPLD和MSP430的嵌入式真空控制系统的设计与实现。内容主要包括(1)系统各部分硬件电路设计与真空控制功能实现 ，硬件系统调试 。(2)嵌入式uClinux操作系统构建和在其上进行的应用程序，设备驱动程序，串行通信程序的开发。（3）CPLD的VHDL程序和MSP430的C430程序设计。 本文目的是解决CSR真空控制系统问题，但对于许多远程数据采集与控制等问题的解决有重要参考价值

CSRm高频系统控制器

HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程，其控制系统是一个庞大的系统，由许多分控制系统组成，高频系统是其重要组成部分之一。加速器的加速过程都是由高频系统来完成的。由于高频控制系统的控制对象就是高频腔体，控制系统的稳定性和输出频率的精确性将直接影响到加速器系统的正常工作，而对于高频系统的状态回读又直接决定了对于高频系统的远程监控能力，所以高频控制系统的设计非常重要。本设计基于现场可编程逻辑门阵列FPGA和数字信号专用处理器DSP搭建， 一方面可以完成从控制中心远程控制高频腔体，另一方面也可以完成对于当前状态的读取，所经过的通道也是多样化的，包括CPCI总线通信，CANBUS总线通信或者是485总线通信。本文的内容包括了1>对于高频控制系统控制对象的分析以及各种控制参数要求。2>组成此系统的硬件部分分析选择以及硬件系统的搭建过程。3>对FPGA和DSP进行程序设计的过程和方法。本文的价值不仅在于对高频系统的控制上，对于其他数据采集系统，远程控制系统以及总线通信和数据分析算法上也有着参考价值

CSR电源调节器硬件平台设计

HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）是国家重大科学工程，其控制系统是一个庞大的系统，由许多分控制系统组成，磁场电源控制系统是CSR控制系统中很重要的一部分。加速器运行的所有过程都为电源所控制，所以我们的控制系统的直接控制对象就是磁场电源。为了保证CSR正常运行，控制过程波形的跟踪精度、速度和稳定度，是数字电源调节器的关键所在。电源控制系统以嵌入式处理器ARM、现场可编程门阵列FPGA为核心，实现了远程数据采集、网络通讯和自动控制等功能。本系统可以进行现场监控与调试，也可以通过集成的100Mbps以太网接口电路进行远程监测与控制，CSR上各处输出电压值和电源运行状态自动传送到中央控制中心，中控中心也可以发送命令查询当前电源设备状态和各种读数。本文主要介绍了基于ARM和FPGA的嵌入式电源控制系统的设计与实现。内容主要包括：(1)系统各部分硬件电路设计与电源控制功能实现 ，硬件系统调试 。(2)装载嵌入式Linux操作系统，测试平台接口信号，通过FPGA生成多路数字PWM波形。本文目的是解决CSR电源控制系统问题，但对于许多远程数据采集与控制等问题的解决有重要参考价值

电荷测量与时序逻辑电路的研究

中国科学院近代物理研究所大科学工程HIRFL-CSR（Heavy Ion Research Facility at LanZhou-Cooling Storage Ring兰州重离子冷却储存环）已建成并处于调试和验收阶段，实验探测系统也正在建设当中。CSRm实验探测系统由外靶系统和内靶系统构成，主要用于核物理实验研究。CSRm TOF测量系统是现阶段CSRm实验探测系统的主要任务之一。 针对CSRm TOF测量系统电荷测量部分，论文阐述了一种采用前端ASIC-SFE16（Saclay Front End 16）芯片实现电荷测量的新型方法。它替代了采用分立元件和电子学插件构建系统的传统方法，着重解决了近代核物理实验中越来越突出的多路多道需求和高性能指标要求。根据我所多丝漂移室探测器的实际情况，我们设计了基于ASIC芯片的电荷测量前端电路板，结合中国科技大学的时间测量数字获取板，我们初步完成了对系统软硬件的测试，给出的实验室性能测试指标，为其在实验探测系统中的应用奠定了坚实的基础。 同时为了选出测量中的有用事例，需要进行事例判选，因此我们研制了多路延迟/脉宽调节时序逻辑电路，主要功能是针对提供的多路逻辑时序信号进行延迟和脉宽调节，支持NIM负信号输入和输出。 文中最后一部分论述了根据在调试过程中出现的实际问题所提出的解决方法，主要是针对电路的可靠性设计和噪声的处理

CSR束流输运系统

国家重大科学工程兰州重离了冷却储存环（HIRFL-CSR）正在兴建当中，本文对其中的束流输运系统进行了详细的光学设计及束流动力学研究。低能束运线传输来自分离扇回旋加速器的束流并匹配注入CSR主环。高能束运线连接着主环和实验环，它的中间一段是放射性次级束流线，设计最大磁刚度为10.64Tm。经过细致的三阶像差校正后，次级束流线的实际动量分辨本领为1200。在研究过程中，用李代数方法证明了一般的四极磁铁在孔径增加时三阶像差反而减小。高能束线有两个分支，分别给物理实验提供高品质的初级束和中高能放射性次级束。另外还设计了一条特殊的束运线，它是基于圆形束方法和能动扫描方案的旋转机架，用重离子（3 < Z < 10）治疗人体深部的肿瘤，并对各种机架的结构进行了比较。最后，讨论了磁铁的误差影响，并简要介绍了束流线的诊断系统。

Hydrogen Bonding and Crystallization in Biodegradable Multiblock Poly(ester urethane) Copolymer

The hydrogen bonding and crystallization of a biodegradable poly(ester urethane) copolymer based on poly(L-lactide) (PLLA) as the soft segment were investigated by FTIR. On slow cooling from melt, the onset and the progress of the crystallization of the urethane hard segments were correlated to the position, width, and relative intensity of the hydrogen-bonded N-H stretching band. The interconversion between the "free" and hydrogen-bonded N-H and C=O groups in the urethane units in the process was also revealed by 2D correlation analysis of the FTIR data. The crystallization of the PLLA soft segments was monitored by the ester C=O stretching and the skeletal vibrations. It was revealed that the PLLA crystallization was restricted by the phase separation and the urethane crystallization, and at cooling rates of 10 degrees C/min or higher, the crystallization of the PLLA soft segments was prohibited.