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.

Physical property measurement of therapeutic carbon ion beam in the shallow-seated tumor therapy terminal at HIRFL

For the first time the physical properties of therapeutic carbon-ion beam supplied by, the shallow-seated tumor therapy terminal at the Heavy Ion Research Facility in Lanzhou (HIRFL) are measured. For a 80.55MeV/u C-12 ion beam delivered to the therapy terminal, the homogeneity of irradiation fields is 73.48%, when the beam intensity varied in the range of 0.001-0.1nA (i.e. 1 X 10(6) - 1 X 10(8) particles per second). The stability of the beam intensity within a few minutes is estimated to be 80.87%. The depth-dose distribution of the beam at the isocenter of the therapy facility is measured, and the position of the high-dose Bragg peak is found to be located at the water-equivalent depth of 13.866mm. Based on the relationship between beam energy and Bragg peak position, the corresponding beam energy at the isocenter of the therapy terminal is evaluated to be 71.71MeV/u for the original 80.55MeV/u C-12 ion beam, which consisted basically with calculation. The readout of the previously-used air-free ionization chamber regarding absorbed dose is calibrated as well in this experiment. The results indicate that the performance of the therapy facility should be optimized further to meet the requirements of clinical trial.

Enhanced photoluminescence of Ar+ implanted sapphire before and after annealing

In this paper, we studied the changes in the photoluminescence spectra of the Ar+ ion implanted monocrystalline sapphire annealed at different atmospheres and different temperatures. Single crystals of sapphire (Al2O3) with the (1 0 (1) over bar 0) (m-samples) orientation were implanted at 623 K with 110 keV Ar+ ions to a fluence of 9.5 x 10(16) ions/cm(2). Photoluminescence measurement of the as-implanted sample shows a new emission band at 506 nm, which is attributed to the production of interstitial Al atoms. The intensity of emission band at 506 nm first increased then decreased with increase in annealing temperature. For the same annealing temperature, the intensity of PL peak at 506 nm of the sample annealed in air was higher than the sample annealed in vacuum. The experimental results show that the intensity of the PL peak at 506 nm of Ar-implanted sapphire can be enhanced by subsequent annealing with an enhancement of nearly 20 times. The influence of thermal annealing of the Ar-implanted samples on the new 506 nm emission band was discussed. (C) 2009 Elsevier B.V. All rights reserved.

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

Effects of treatment in different atmosphere on Pt3Sn/C electrocatalysts for ethanol electro-oxidation

Pt3Sn/C catalyst was prepared by a modified polyol process and treated in air, H-2/Ar, and Ar atmosphere, respectively. XRD analyses indicate that all of these catalysts have face-centered cubic (fcc) crystal structure. Temperature-programmed reduction (TPR) experiments show that more Sn exists in zero-valence in the Ar-treated PtSn catalyst than in the others. Cyclic voltammetry (CV), chronoamperometry (CA) experiments, and the performance tests of direct ethanol fuel cell (DEFC) indicate that the catalytic activity of PtSn/C for ethanol oxidation was affected significantly by the chemical state of Sn in catalyst particles. The as-prepared PtSn/C gives the higher power density, while Ar-treated PtSn/C shows the lower cell performance. It seems that the multivalence Sn rather than the zero-valence Sn in the PtSn catalyst is the favorable form for ethanol oxidation. Energy dispersion X-ray analysis (EDX) of the PtSn/C-as prepared and PtSn/C (after stability test) shows the active species (platinum, tin, and oxygen) composition changed to a different extent. Further attempt to improve the catalyst stability is needed.

Effects of reaction conditions on the selective oxidation of propane to acrylic acid on Mo-V-Te-Nb oxides

An effective Mo-1 V(0.3)Te(0.23)Nb(0.12)Ox catalysts for the selective oxidation of propane to acrylic acid was successfully prepared by using rotavap method. The catalyst was characterized by XRD and shown to contain (V0.07Mo0.93)(5)O-14, (Nb0.09Mo0.91)O-2.8,3MoO(2)(.)Nb(2)O(5), Mo5TeO16 and/or TeMo4O13, Te4Nb2O13 and a new TeMO (TeVMoO or TeVNbMoO; M = Mo, V and Nb) crystalline phase as the major phase. Regardless of the intrinsic catalytic characteristics of the catalyst, the external reaction conditions would have strong effects on the catalytic performance for propane oxidation. So in this paper, the effects of reaction conditions were investigated and discussed, including temperature, space velocity, V(air)/V(C3H8) ratio and V(steam)/V(C3H8) ratio. A stability test was also carried out on Mo1V0.3Te0.23Nb0.12Ox catalyst. The experimental run was performed during 100 h under the optimized reaction conditions. During the 100 h of operation, propane conversion and acrylic acid selectivity remained at about 59 and 64%, respectively. (C) 2004 Elsevier B.V. All rights reserved.