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。

兰州CSRm小丸内靶热力学和流体力学的研究

兰州CSRm内靶终端是进行强子物理实验的平台，可开展奇异介子产生和衰变的研究、重子谱的研究、多夸克态的研究及介子介质效应和手征对称破缺与恢复等多方面的研究。这些物理目标都需要内靶实验终端提供足够多的事件率，并能进行准确的径迹构建。在众多候选的内靶装置中，小丸靶具有其它内靶所欠缺的优点，如可以获得与外靶实验相比拟的实验亮度，可以配置4π立体角的探测器单元等。因此，小丸靶被确定为CSRm内靶实验终端中的主要内靶之一。小丸内靶（Pellet Internal Target）就是将氦以外的某种气体通过低温冷却而形成的固体微球。小丸内靶靶束与储存环离子束在反应室正交并发生相互作用，其反应事例被反应室周围环绕的探测器单元探测到并被记录下来。这篇论文对小丸内靶装置的结构进行了简要的介绍，并对小丸在反应室内的热力学行为进行了模拟。计算表明，靶丸速度是影响靶丸在反应区正常运行的重要因素之一。靶丸速度越大，靶丸在反应室内爆炸的可能性越小。通过对小丸的速度进行的流体动力学分析，发现即使对所有实验条件进行优化，小丸内靶的速度至多能达到100 m/s左右

CSRm内靶实验中的轻离子束流储存寿命研究

束流储存寿命对于储存环的建造和内靶实验都是一个很重要的参数。由于重离子冷却储存环工程的优化，HIRFL-CSR主环将能提供2．SGev的质子束流，这为强子物理研究提供了一个很好的平台。设计并建立一套针对强子物理的内靶系统己经列入到计划当中，与内靶相关的束流储存寿命研究也随之展开。本论文首先分析了在内靶实验中束流储存寿命的影响因素，即真空管道中的残余气体分子、冷却电子束和内靶，以及束内散射和集体效应等，并用理论解析和数值计算的方法，对各种因素的影响程度进行估算。研究表明，内靶散射影响下的束流储存寿命比其他因素导致的短2～3个数量级，内靶是影响束流寿命的决定性因素。其次，对CSRm将来实验中主要用到的Pelle七内靶和碳薄膜靶做了简要介绍，并计算了它们的有效靶厚大约为lx10、切ms／cmZ和5火1017atoms／CmZ。再者，用理论推导方法，对内靶的多次库仑散射和束流能量损失扰动对束流的影响进行了研究，推导了束流的横向和纵向发射度增长与束流每次打靶产生的小库仑散射角均方值气s和相对动量分散气了：之间的关系，并通过数值计算的方法给出了CSRm内靶实验条件的发射度增长曲线。最后，建立了内靶散射的MOnte-Carlo模拟程序，在模拟数据的基础上，总结研究束流的发射度增长规律，以及束流存储寿命与内靶厚度和束流能量的关系。计算表明，当存在Pellet靶（1、1016atoms／cm2）和c膜（5*1017 atoms／cmZ）时，2800Mev质子束的束流储存寿命分别为397秒和0．7秒，将来的内靶实验亮度大约为2 x 1033cm-2·s-1。

Native growth of vertically pattened ZnO nanowire arrays under mild conditions without templates or catalysts

Based on the implications of a pellet experiment,we have designed and implemented a low temperature(≤90℃) approach to generate native patterned,vertically aligned ZnO nanoarrys without any templates or catalysts.This simple,economic and spontaneous patterning process offers a promising avenue for overcoming several inherent limitations of the artificial manners[1].While the purity,orientation and electrical properties of the as prepared materials allow them to be applied in various fields.

Magnetic and electric properties of Bi(La)Sr(Ca)Mn2O6

Bi1-xLaxSrMn2O6 and BiSr1-xCaxMn2O6 are prepared by solid state reaction. They are n-type semiconductors with ferromagnetism at room temperture. When Bi is substituted partly by rare earth, a negative magnetoresistance effect is observed in the pellet of Bi1-xLaxSrMn2O6. There are semiconductor-metal transitions at 820 K in BiSrMn2O6. The transitions are attributed to the magnetic transition at high temperature. The substitution of Ca for Sr makes the transition temperature increase. However, when Bi is partly substituted by La, the solid solution does not change into metal. (C) 1996 Academic Press, Inc.

SUPERCONDUCTIVITY IN BI1.5PB0.4SBXSR2CA2CU2OY SYSTEM (X=0-0.32)

The effect of doping with various amount of Sb (0.06-0.32) to (Bi,Pb):Sr:Ca:Cu = 1:1:1:1 system were studied with XRD and Tc measurements. The presence of Sb promotes the conversion of low Tc phase (2212 phase) to high Tc phase (2223 phase) and at around Sb = 0.18 the 2212 phase nearly completely disappears; but at the same time a new phase of unknown structure appears even with Sb = 0.06 showing that the incorporation of Sb into the Bi-based superconducting phase is of very low concentration. Tc measurements show that the optimum concentration of Sb-doping is around 0.10 and that unknown phase has an adverse effect to the superconducting properties; a composition disproportion at the surface of pellet was observed.

Formation and growth of Bryopsis hypnoides lamouroux regenerated from its protoplasts

Tissue culture, SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and spectra analysis were used for studying the aggregation mechanism of protoplasts from Bryopsis hypnoides Lamouroux and the discrepancy between the protoplast-regenerated plants and the wild type. The aggregation of protoplasts from B. hypnoides was observed in natural seawater and artificial seawater with different pH values, and the location and mechanism of the materials causing the aggregation were also studied. Results showed that the protoplasts could aggregate into some viable spheres in natural seawater and subsequently grow into mature individuals. Aggregation of the protoplasts depended exclusively upon the pH value (6-11), and the protoplasts aggregated best at pH 8-9. Some of the extruded protoplasts were separated into two parts by centrifugation: the pellet (PO) and the supernatant (PL). The PO could aggregate in artificial seawater (pH 8.3) but not in PL. No aggregation was found in PO cultured in natural seawater containing nigericin, which can dissipate the proton gradients across the membrane. These experiments suggest that the aggregation of protoplasts is proton-gradient dependent and the materials causing the aggregation were not in the vacuolar sap, but located on the surface or inside the organelles. Furthermore, the transfer of the materials across the membrane was similar to Delta pH-based translocation (Delta pH/TAT) pathway that occurs in the chloroplasts of higher plants and bacteria. Obvious discrepancies in both the total soluble proteins and the ratio of chlorophyll a to chlorophyll b between the regenerated B. hypnoides and the wild type were found, which may be related to the exchange of genetic material during aggregation of the organelles. In the process of development, diatom Amphora coffeaeformis Agardh attached to the protoplast aggregations, retarding their further development, and once they were removed, the aggregations immediately germinated, which showed that diatoms can affect the development of other algae.

Recovery and fate of three species of marine dinoflagellates after yellow clay flocculation

The recovery and fate of three species of dinoflagellates, Alexandrium tamarense, Cochlodinium polykrikoides and Scrippsiella trochoidea, after having been sedimented by yellow clay, were investigated in the laboratory. The effect of burying period in yellow clay pellet and mixing on the recovery of settled algal cells were studied. The morphological changes of algal cells in yellow clay pellet were also tracked. Results showed that there was almost no recovery for A. tamarense and C. polykrikoides, and the cells decomposed after 2-3 days after visible changes in morphology and chloroplasts. There was some recovery for S. trochoidea. Moreover, S. trochoidea cysts were formed in clay pellet during the period of about 14 days, with the highest abundance of 87 000 cysts g(-1) clay and the incidence of cyst formation of 6.5%, which was considered as a potential threat for the further occurrence of algal blooms. S. trochoidea cysts were isolated from yellow clay and incubated to test their viability, and a germination ratio of more than 30% was obtained after incubation for 1 month. These results showed the species specificity of the mitigation effect of yellow clay. It is suggested that cautions be taken for some harmful species and thorough risk assessments be conducted before using this mitigation strategy in the field.

内蒙古龙头山Ag-Pb-Zn多金属矿床成矿模式及找矿模型

The recent years research indicated that middle-south section of Da Hinggan Mountains metallogenic belt has two periods(Hercynian and Yanshanian) characteristics of metallogenesis, as well as the most of ore deposits in the area closely relate to Permian strata. Longtoushan ore deposit discovered in 2004 is an Ag-Pb-Zn polymetallic ore deposit born in Permian and located in the east hillside of the metallogenic belt, which has considerable resources potentials. It has important research value for its good metallogenic location and blank research history. Base on the detail field geology studies, the geology characteristics of "two stages and three kinds of metallogensis" has established. According to further work through geochemistry research including trace element, REE, S, Pb and Sr isotope, as well as petrography, microtemperature measurement, Laser Raman analysis and thermodynamics calculation of fluid inclusion, origin and characteristic of the ore-forming material and fluid has been discussed. And a new technology of single pellet Rb-Sr isochrones has been tried for dating its born time. Bae on above work, study of ore deposit comparison has been carried out, and metallogesis controlling factor and geological prospecting symbol have been summarized. Finally, metallogenic model and prospecting model have been established. According to above, the next step work direction has been proposed. Main achievement of the paper are listed as follow: 1.Longtoushan ore deposit has experienced two metallogenic periods including hot-water sedimentation period and hydrothermal reformation period. There are three kinds of metallizing phase: bedded(or near-bedded) phase, vein-shaped phase and pipe-shaped phase. The mian metallogenic period is hot-water sedimentation period. 2.Ore deposit geochemistry research indicated that the metal sulfides have charcateristic of hot-water sedimentation metallogensis, but generally suffered later hydrothermal transformation. The barite mineral isotope content is homogenous, showing the seabed hot-water sedimentation origin characteristic. Wall rock, such as tuff is one of metallogenic material origins. Both of Pb model age and Rb-Sr isochrone research older age value than that of strata, possibly for been influenced by hydrothermal transformation, and interfusion of ancient basis material. 3.There are two kinds of main metallogenic fluid inclusion in barite of the Longtoushan ore deposit, which are rich gas phase( C type) and liquid phase (D type). Their size is 2～7um, and principal components is H2O. Both kinds of fluid inclusion have freezing point temperature -7.1～-2.4℃ and -5.5～-0.3℃, salinity 4.0～10.6wt% and 0.5～8.5wt%, homogeneous temperature 176.8～361.6℃ and 101.4～279.9℃, which peak value around 270℃ and 170℃, respectively. Density of the ore-forming fluid is 0.73～0.97g/cm3, and metallogenic pressure is 62.3×105～377.9×105Pa. Above characteristic of the fluid inclusion are well geared to that of ore deposit originated in seabed hot-water sedimentation. 4.Through the comparison research, that Longtoushan ore deposit has main characteristic of hot-water sedimentation ore deposit has been indicated. Ore-forming control factor and prospecting symbol of it has been summarized, as well as metallogenic model and prospecting model. Next step work direction about prospecting has also been proposed finally.