中能区丰中子核~(11)Li的反应总截面的测量(英文)

利用HIRFL提供的50MeV/u的~(13)C束流轰击Be靶,通过RIBLL选择出放射性核素~(11)Li.实验采用透射法测量了25—45MeV/u的~(11)Li在~(28)Si靶上的反应总截面.采用双参数Gauss密度分布形式,利用Glauber模型很好地拟合了高能和中能区的~(11)Li实验数据,并从密度分布中提取了核的物质均方根半径.

Li~-和Na~-单电子解离过程的研究

采用交叉束方法 ,利用负离子源产生的 3— 19keV的Li- 和Na- 轰击惰性气体靶He ,Ne和Ar ,通过静电偏转和位置灵敏探测器区分碰撞后中性粒子束和负离子束 ,测量了不同碰撞系统的中性粒子计数与相应入射负离子计数的比值R(E) ,并得到R(E)与入射负离子能量、负离子种类和靶原子种类的关系 .

晕核~(11)Be和~(11)Li的能谱

基于自相似结构壳模型,并考虑到单粒子轨道的均方根半径的振动,提出了尺度共振模型。在尺度共振模型中,考虑了晕中子轨道的尺度共振和核实表面的尺度共振。用尺度共振模型成功地计算了~(11)Be和~(11)Li的激发谱。

Measurement of total reaction cross section for neutron-rich nucleus Li-11 on Si-28 target at medium energy

The neutron-rich nucleus Li-11 is separated by the radioactive ion beam line RIBLL at HIRFL from the breakup of 50MeV/u C-13 on Be target. The total reaction cross sections for Li-11 at energies range from 25 to 45MeV/u on Si target have been measured by using the transmission method. The experimental data at high and low energies can be fitted well by Glauber model using two Gauss density distribution. The matter radius of Li-11 was also deduced.

Li同位素的结构和性质

锂同位素的结构性质，特别是滴线核 ~(11)Li的异常特性，目前微观机制并不很清楚。本文系统地研究了锂同位素基态和低位态的性质，包括基态结合能、能谱、电磁矩和电磁跃迁性质、及β衰变性质，发现~6Li核基态的四极矩敏感地依赖于相互作用力中的张量力分量，~6Li、~7Li和~8Li核的第一激发态电磁跃迁几率增大，呈现集体性，可能是由集团结构所致，对远离核~9Li的某些态需要考虑sd-shell组态侵入的影响。在~(6-9)Li核性质系统研究的基础上，发现滴线核~(11)Li核的结构性质仍可在壳模型框架内得到解释，平均场效应是引起其奇异性质的微观起因，对于~(10)Li核的性质仍需进一步探讨。对锂同位素引进平均场的同位旋依赖项尚需近一步研究。在3

Li蒸气电荷交换负He离子源的设计与调试

本论文分别从离子源的历史发展，负He离子的产生机理，设计思想及调试运行等方面描述了锂蒸气电荷交换负He离子源。该离子源可以引出1μA以上的He~-离子流，可连续稳定运行十二小时以上。本文研究了其性能，获得了束流强度随蒸气温度、引出电压的变化规律，并对蒸气靶靶厚、电荷交换截面、转化率进行了简单的估算。当引出电压为18KV，蒸气温度500 ℃时，靶厚为8.5 * 10~(13)cm~(-2)，交换截面为1.0 * 10~(-16)cm~2， 转化率为0.86%。最大负He离子流强为1.37℃A.该源配置在2 * 2MeV串列静电加速器上，可在核物理实验和离子束分析提供良好的He负离子流和负H离子流。本文还提出了一些改进完善意见和设想

Influence of iron promoter on catalytic properties of Rh-Mn-Li/SiO2 for CO hydrogenation

The effect of iron promoter on the catalytic properties of Rh-Mn-Li/SiO2 catalyst in the synthesis Of C-2 oxygenates from syngas was investigated by means of the following techniques: CO hydrogenation reaction, temperature-programmed reduction (TPR), temperature-programmed desorption and reaction of adsorbed CO (CO-TPD and TPSR) and pulse adsorption of CO. The results showed that the addition of iron promoter could improve the activity of the catalysts. Unexpectedly, the yield of C-2 oxygenates increased greatly from 331.6 up to 457.5 g/(kg h) when 0.05% Fe was added into Rh-Mn-Li/SiO2 catalyst, while no change in the selectivity to C-2 oxygenates was observed. However, the activity and selectivity Of C-2 oxygenates were greatly decreased if the Fe amount exceeded 1.0%. The existence of a little iron decreased the reducibility of Rh precursor, while the reduction of Fe component itself became easier. CO uptake decreased with increasing the quantity of Fe addition. This phenomenon was further confirmed by CO-TPD results. The CO-TPD and TPSR results showed that only the strongly adsorbed CO could be hydrogenated, while the weakly adsorbed CO was desorbed. We propose that Fe is highly dispersed and in close contact with Rh and Mn; such arrangements were responsible for the high yield Of C-2 oxygenates. (C) 2002 Elsevier Science B.V. All rights reserved.