放射性9C束流不同贯穿深度上的线能谱测量

为阐述放射性⁹C束流应用于治癌的物理基础, 运用一个球形生物组织等效正比计数器测量了⁹C束流不同贯穿深度上的线能谱, 得到了沿束流贯穿深度上的剂量平均线能分布. 将实验测量得到的线能谱转换成为不同传能线密度在吸收剂量中所占份额的分布, 得到了该⁹C束流在不同贯穿深度上的剂量平均传能线密度分布. 将生物组织等效正比计数器测量得到的与先前通过平行板正比计数器测量得到的该⁹C束流的剂量平均传能线密度分布进行比较, 发现: 在束流入射通道上, 两者测量数据符合很好, 而在束流Bragg峰附近⁹C离子的沉积区域, 由组织等效正比计数器测量得到的剂量平均传能线密度值大于由平行板正比计数器测量得到的值.     

22Na放射源慢正电子束流插入装置的研制

北京慢正电子强束流是利用北京正负电子对撞机电子直线加速器电子打靶产生的高强度低能单色正电子束流. 为了提高强束流的机时利用效率和节省强束流用于新建实验站的调试机时, 设计了一套基于²²Na放射源的慢正电子束流装置插入到强束流输运线上. ²²Na放射源慢正电子束流插入装置主要包括²²Na放射源及慢化体、E×B能量选择器、多级静电加速管、磁场输运系统、真空系统、高压绝缘和辐射防护措施等.     

CSRm内靶实验中的轻离子束流寿命模拟研究

 建立了内靶对兰州冷却储存环主环束流影响的单粒子跟踪模拟程序,对pellet小丸靶和碳靶对束流带来的负面影响进行了模拟研究,主要讨论CSRm内靶实验中的束流存活率和束流寿命状态。结果显示利用厚度为1×10¹⁶ atoms×cm^-2小丸内靶时,2.6 GeV质子束流寿命在100 s量级,而对于目前技术水平下的碳膜靶 (厚度为 5×10¹⁷ atoms×cm^-2),质子束流寿命为s量级;束流寿命和束流能量基本成正比关系,束流寿命和内靶厚度近似成反比关系。     

半导体器件单粒子效应的加速器模拟实验

 着重描述了应用加速器开展半导体器件的单粒子效应实验研究的方法。采用金箔散射法可以降低加速器束流几个量级，从而满足半导体器件单粒子效应实验的要求。研制的弱流质子束流测量系统和建立的质子注量均匀性测量方法解决了质子注量的准确测量问题。实验测得静态随机存取存储器的质子单粒子翻转截面为10^-7 cm²·bit^-11量级，单粒子翻转重离子LET阈值为4～8MeV·cm²/mg，重离子单粒子翻转饱和截面为10^-7 cm²·bit^-1量级。     

136Ba的10+同质异能态

利用450MeV的⁸²Se束流轰击¹³⁹La靶,通过核子转移反应产生了¹³⁶Ba,用在束γ谱学方法测量了其激发态的γ衰变,观测到了它的10⁺态同质异能态并得到该同质异能态的寿命为94ns.     

高能不等核碰撞和弛豫时间的相对论动力论方程描述

本文用相对论动力论方程描述高能重离子碰撞时空演化,并用它分析在200A GeV的¹⁶O束流和³²S束流下,于快度中心区的末态粒子快度分布,确定了不同系统的弛豫时间.     

丰中子核8He在Si靶上的反应总截面的测量

利用HIRFL 50MeV/u ¹³C束流在Be靶上碎裂,RIBLL选择出丰中子放射性次级束流⁸He,实验测量了25—40MeV/u ⁸He在²⁸Si靶上的反应总截面.采用双参数HO密度分布形式,通过微观Glauber模型拟合⁸He实验数据,发现⁸He具有扩展的中子密度分布.实验结果与Warner反应总截面实验和Alkhazov弹性散射实验结果较好地符合.     

高能不等核碰撞和弛豫时间的Fokker-Planck方程描述

本文提出用Fokker-Planck方程描述高能重离子碰撞时空演化,并用它分析在200AGeV的¹⁶O束流和³²S束流下,末态粒子的快度分布,并确定了不同系统的弛豫时间,得到了可以和通用经验数值相比较的结果.     

12N直接碎裂反应研究

描述了在兰州放射性束流线(RIBLL)上用78.6MeV/u的¹⁴N束流轰击Be靶产生出34.9MeV/u的¹²N次级束流. 利用¹²N轰击Si靶作为次级靶, 利用直接碎裂反应测量它的反应总截面. 利用理论模型进行了计算, 理论计算和实验结果符合的很好. 发现¹²N的质子密度分布相对于中子而言, 有一个很大的弥散.     

19F+27Al耗散反应中双核系统的转动与衰变

测量了¹⁹F+²⁷Al耗散反应产物B,C,N,O,F和Ne的激发函数, 入射束流的能量从110.25MeV到118.75MeV,能量步长为250keV. 用能量自关联函数方法从激发函数中提取了各反应产物的平均衰变宽度, 利用同时考虑反应中所形成的中间双核系统的转动特性和衰变特性而发展了的Ericson核反应统计理论, 讨论了¹⁹F+²⁷Al耗散反应中双核系统随时间的演化过程.     

Dielectronic recombination at low energy range with Boron-like Ar13+at the CSRm

In order to extend the dielectronic recombination (DR) experiments from the main cooler storage ring CSRm with intermediate charge state ions to the experimental cooler storage ring CSRe with highly charged ions and even radioactive ions, a test electron-ion recombination experiment of B-like Ar¹³⁺ ions was performed with a section of the new electron beam energy detuning system, which will be installed at the CSRe. We present the measured and also the calculated DR spectra for the ∆n = 0 resonances from 0 to 3 eV. The experimental results agree very well with the previous DR experimental data from CRYRING, and the energy resolution reached 30 meV full width at half maximum. This test experiment demonstrates that the reliability and stability of the newly developed electron beam energy detuning system are satisfactory for the upcoming DR experiments at the CSRe. However, we found large discrepancies between the experimental result and the calculation in both resonance positions and the intensities of the recombination spectrum below 0.7 eV, which indicate that precise calculation of the DR spectrum of multielectron ions is still a challenge.     

基于EPICS的CSRe束流诊断控制系统升级

兰州重离子加速器(HIRFL)冷却存储环的实验环（CSRe）提供高品质的束流用于高精度的质量测量、原子物理等实验研究,实现束流参数的准确测量是进行物理实验的前提保障。目前,CSRe加速器控制系统已升级为EPICS架构。介绍了基于EPICS的束流诊断控制系统现状,并利用升级后的控制系统测量了束流相关参数。其中,束流位置系统能够测量注入束流的逐圈位置信息,测量结果发现束流在注入过程中存在一定程度的震荡,影响注入效率。流强测量系统通过高分辨的数据采集卡实现对DCCT信号的精确测量,同时增加了D事例触发功能。升级后的控制系统,可以实现束流参数的测量,并集成于加速器控制系统的EPICS CSS界面。     

Electron cooling experiments in CSR

The six species heavy ion beam was accumulated with the help of electron cooling in the main ring of Cooler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). The ion beam accumulation dependence on the parameters of cooler was investigated experimentally. The 400 MeV/u ¹²C⁶⁺ and 200 MeV/u ¹²⁹Xe⁵⁴⁺ were stored and cooled in the experimental ring CSRe, and the cooling force was measured in different conditions.

     

Schottky mass spectrometry at the heavy ion storage ring ESR

Schottky mass spectrometry is a novel method of precision nuclear mass spectrometry based on the measurement of the revolution frequencies of cooled ions in storage rings performed by non-destructive frequency analysis of the beam noise, the well-established Schottky diagnosis technique. The method was applied for the first time at the Experimental Storage Ring ESR at GSI observing electron cooled highly charged ions up to bare nuclei at relativistic energies around several hundred MeV/u. To demonstrate the performance and feasibility of the method at the ESR, experimental tests have been carried out using beams of nuclear fragments produced in the ring itself by the interaction of different primary beams with the internal gas jet target. Futhermore, first Schottky mass measurements of secondary nuclear beams produced by projectile fragmentation of Au and Bi primary beams in a thick Be-target were carried out in order to determine the masses for numerous heavy neutron deficient nuclei which had not been measured before. Relative accuracies for the measured mass values in the order of 1×10^–6 and below can be achieved. The method is briefly discussed and some early results are presented.     

A pilot experiment for mass measurement at CSRe

A pilot experiment of mass measurement was performed at CSRe with the method of isochronous mass spectrometry. The secondary fragments produced via RIBLL2 with the primary beam of 400 MeV/u 36Ar delivered by CSRm were injected into CSRe. The revolution periods of the stored ions, which depend on the mass-to-charge ratios of the stored ions, were measured with a time-of-flight detector system. The results show that the mass resolution around 8×10-6 for Δm/m is achieved.     

CSRe肖特基谐振腔数据获取远控系统

中国科学院兰州近代物理研究所实验冷却储存环CSRe上的肖特基谐振腔的数据获取远控系统已搭建完成。该系统为核素质量与寿命测量平台的重要组成部分。其主要包含了两个构建在图形化界面上的数据获取控制程序和数据监测程序。该系统提供了多种功能,以快捷地辅助调整实验设置。系统充分利用了频谱仪及数据记录仪的自身功能,并借助独立触发系统与远程电源开关,补足了成品数据记录仪的硬件缺失,得以成功实现自动获取大数据量数据文件的设计目标。除满足了核素质量与寿命的测量需求之外,该系统也可用于其他以CSRe上肖特基谐振腔为测量设备的实验。     

Optical detection system for laser cooling and precision laser spectroscopy of relativistic highly charged ions at the CSRe

Laser cooling and precision laser spectroscopy experiments of relativistic highly charged ions are being prepared at the heavy-ion experimental cooler storage ring (CSRe). Optical detection of fluorescence photons, emitted from the laser-excited ions, is extremely important for both powerful methods. In this paper, we briefly report on the current status of the existing optical detectors and also on their performance during laser cooling of relativistic Li-like ¹⁶O⁵⁺ ion beams at the CSRe. In addition, we introduce the designs for our new optical detection systems, which have much higher photon detection efficiencies and can cover a much broader wavelength range. These detector systems will be used for the upcoming laser spectroscopy experiment of Li-like ¹⁶O⁵⁺ ions, as well as for future laser spectroscopy experiments with other highly charged ions.     

Simulation and measurement of the resonant Schottky pickup

A resonant Schottky pickup with high sensitivity, built by GSI, will be used for nuclear mass and lifetime measurement at CSRe. The basic concepts of Schottky noise signals, a brief introduction of the geometry of the detector, the transient response of the detector, and MAFIA simulated and perturbation measured results of characteristics are presented in this paper. The resonant frequency of the pickup is about 243 MHz and can be slightly changed at a range of 3 MHz. The unloaded quality factor is about 1072 and the shunt impedance is 76 kΩ. The measured results of the characteristics are in agreement with the MAFIA simulations.     

利用HIRFL-CSR开展分子离子复合离解研究的可行性分析

介绍了储存环高精度分子谱学研究的科学意义、 国内外研究现状和利用HIRFL-CSR开展该项研究的优势, 着重论证了HIRFL-CSR分子离子注入实验环的总体设计方案和技术方案。 通过在HIRFL-CSR实验环上增建一条分子离子注入线, 将实验环改造成能兼顾现有物理实验和大分子物理研究的综合性研究平台, 为分子离子复合离解研究提供良好的技术支撑。 特别是质量数大于70的分子离子, 能显著提高其能量分辨。 In the present paper, it is introduced the scientific background and the current status of the high precision spectroscopy of the molecular ions at cooler storage ring. The advantages to study the dissociative recombination(DR) processes using cooler storage ring CSRe are discussed. The physics design,the main parameters of the injection beam line and the injection of the molecular ions into the CSRe and the key techniques are described in detail. With a new injection beam line,HIRFL-CSRe will be reconstructed to a multi discipline research platform,offering good opportunities for the study of DR processes of molecular ions,especially for that of the molecular ions of m>70 amu with much improved resolution.     

Simulation of longitudinal dynamics of laser-cooled and RF-bunched C~(3+) ion beams at heavy ion storage ring CSRe

Laser cooling of Li-like C~(3+)and O~(4+)relativistic heavy ion beams is planned at the experimental Cooler Storage Ring(CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic~(12)C~(3+)ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the~(12)C~(3+)ion beams by scanning the frequency of the RF-buncher or continuous wave(CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained.Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe.