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1×1016atoms.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5×1017atoms.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。

HIRFL-CSR实验环团簇内靶的首批测试实验

内靶装置是兰州重离子冷却储存环(HIRFL-CSR)实验环的一个重要的插入件,也是世界上第一个嵌入在重离子储存环中的内靶装置,它位于HIRFL-CSR实验环的一个直线段.团簇内靶具有传统外靶所不具备的一些优点,如高亮度、高精度和高灵敏度等.这些优点可使我们在内靶实验平台上进行一些高精度的物理实验.为满足不同物理实验的需求,内靶可以有两种工作模式:非极化靶运行模式和极化靶运行模式,用于为实验环内的物理实验提供厚度为1011~1013atoms/cm2的非极化靶和极化靶.团簇靶是属于非极化靶运行模式,它采用超声喷气和冷凝相结合的方法获得团簇粒子束,并在碰撞靶室中与环内束流相碰撞,未反应的团簇束被收集级抽走.团簇内靶可以提供靶密度约为2×1013atoms/cm2的Ne、Ar、Kr、Xe和N2、CH4等团簇束.目前已完成了团簇靶的现场安装和准直,并进行了真空达标、喷嘴冷却和稳定性等首批测试实验.本文主要介绍团簇靶的工作原理和首批测试实验结果.

栅扫描重离子束治癌束流配送系统对运动靶区的适形放疗冰(Ⅰ)模拟计算

从理论上研究了在主动型栅扫描束流配送系统下,靶体运动对靶区剂量均匀性以及重离子治疗适形程度的影响.模拟计算了在实验测量得到的脉冲束流照射下,栅扫描系统引导束流对运动靶体实施照射后,靶体运动模式与靶区各等能量断层剂量分布均匀性的关系.由这些模拟计算结果,得到了一些针对运动靶体提高靶区剂量分布均匀性的策略.模拟计算提供了一种评估运动靶体上剂量分布的有效手段,其结果及内涵为今后该方向上的可行性实验研究奠定了坚实的基础.

中子星的转动惯量与表面红移的研究

在温度、密度及同位旋相关的核物质状态方程的基础上，通过求解Ｔｏｌｍａｎ－Ｏｐｐｅｎｈｅｉｍｅｒ－Ｖｏｌｋｏｆｆ方程，得到了中子星的转动惯量与表面红移．计算结果表明，中子星的转动惯量较强地依赖于核物质的不可压缩系数与对称能强度系数，而对核子有效质量不太敏感；中子星的表面红移却对对称能强度系数不太敏感，而较强地依赖于不可压缩系数与核子有效质量．

Size modification of Au nanoparticles induced by slow highly charged ions Ar-40(q+) irradiation

Size modification of Au nanoparticles (NPs), deposited on the Au-thick film surface and irradiated by slow highly charged ions (SHCI) 40Arq+ (3 6 q 6 12) with fixed low dose of 4.3 1011 ions/cm2 and various energy ranging from 74.64 to 290.64 keV at room temperature (293.15 K), was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effect of projectile kinetic energy on the modified size of NPs was explored by an appropriate choice of the fixed process parameters such as ion flux, irradiation temperature, incident angle, irradiation time, etc. The morphological changes of NPs were interpreted by models involving collisional mixing, Ostwald ripening (OR) and inverse Ostwald ripening (IOR) of spherical NPs on a substrate. A critical kinetic energy as well as a critical potential energy of the projectile in the Au NPs size modification process were observed.

关于强流ECR质子源氢等离子体发射光谱的诊断研究；OES diagnostics of H_2 plasma in an intense ECR proton source

本文通过发射光谱诊断方法,用H_2等离子体的辐射碰撞模型对连续溃入的微波功率和全永磁磁场约束下产生高密度的H_2等离子体进行光谱诊断,计算出一定放电条件下(微波功率200-700 W,压强0-2 Pa)H~+的密度为1010-1011 cm~(-3),另外讨论了实验中观察到的Balmer系氢原子发射光谱强度随放电条件的变化规律。

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。

Quantitative evaluation of the interaction between pUC19DNA and ovalbumin by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was used to study the interaction between pUC19DNA (pUC19) and ovalbumin (Ova). Samples containing pUC19 and Ova at various ratios were incubated at room temperature and were then separated by CZE with tris-acetate buffer at pH 7.2. Reduction in ultraviolet (UV) absorbance of pUC19 was due to the decrease of free pUC19 after binding to Ova. The binding constant of the interaction calculated from the Scatchard plot was (1.46+/-0.15) x 10(5) M-1. The use of polyacrylamide-coated capillary showed better effects than that of uncoated capillary. The results show that it is important to keep a constant ionic strength in the samples in order to obtain accurate quantitative data in binding assays by CZE.

Anodic Stripping Voltammetry at Bismuth-Coated and Uncoated Carbon Microdisk Electrodes:Application to Trace Metals Analysis in Flood Samples

This article reports on the performance of a bismuth-coated carbon microdisk electrode (BiFμE) for the determination of trace heavy metals by anodic stripping voltammetry (ASV). The BiFμE was prepared by electrodeposition of a metallic bismuth film onto the microdisk, by applying an in-situ electroplating procedure. To test the performance of the BiFμE, ASV measurements were performed on synthetic solutions containing Cd2+, Pb2+, and Cu2+ as target ions. The results indicated that cadmium and lead gave well-defined ASV peaks with no interference, and their quantitative determination could be carried out straightforwardly. In particular, linear calibration curves over the range 5.0 x 10-8-1.0 x 10-6M for both ions, and detection limits of 7.8 and 2.9 nM, for cadmium and lead, respectively, after applying a 60 sec preconcentration step, were obtained. The reproducibility was also satisfactory, the relative standard deviation (RSD) being within 2.5% for both ions. Copper, instead, gave an ASV response that. in most experimental conditions, overlapped with that of bismuth. This circumstance made the determination of copper at the BiFμE difficult. Since the latter element could be detected reliably at the uncoated carbon microdisk electrode (CμE), both BiFμE and CμE were employed, respectively, for the determination of lead and copper ions in drinking water, wine, and tomato sauce.

侵蚀细沟水力学特性及细沟侵蚀与形态特征的试验研究

本文进行了一系列水槽试验 ,研究不同长度的侵蚀细沟在坡度及入流量影响下的浅水水流水力学特性、侵蚀量及细沟的形态特征 .所采用的土壤材料为砂壤土 ,试验使用四种入流流量 ,四种坡度 ,四种细沟长度 .记录水流速度、沟宽及径流中的泥沙含量 ,并用多元回归方法分析了它们与坡度、入流量或它们的交互项之间的关系 .提出了一种数学模型来描述试验中沟宽的周期性形态变化 .提出了通过试验得出的不同细沟长度的产沙量来确定水流输沙能力的方法 ,并得出出测定输沙能力的采样长度为 2～ 4m ,通过对细沟形态变化分析进一步说明了所确定的水流输沙能力采样长度的正确性