用于次级束物理实验的低气压多丝室

阐述了位置灵敏探测器在核物理实验中的作用,同时详细叙述了低气压多丝室(LP-MWPC)的工作机理及时间、位置特性。描述了用于较高能量轻粒子的次级束实验的LP-MWPC的结构和测试结果,得到ΔX=ΔY=0.7mm的位置分辨。

Relativistic Distorted-Wave Collision Strengths of Ni-, Cu- and Zn-like Au Ions

Excitation energies and electron impact excitation strengths from the ground states of Ni-, Cu- and Zn-like Au ions are calculated. The collision strengths are computed by a 213-levels expansion for the Ni- like Au ion, 405-levels expansion for the Cu-like Au ion and 229-levels expansion for the Zn-like Au ion. Configuration interactions are taken into account for all levels included. The target state wavefunctions are calculated by using the Grasp92 code. The continuum orbits are computed in the distorted-wave approximation, in which the direct and exchange potentials among all the electrons are included. Excellent agreement is found when the results are compared with previous calculations and recent measurements.

Biodosimetry estimate for high-LET irradiation

The purpose of this paper is to prepare for an easy and reliable biodosimeter protocol for radiation accidents involving high-linear energy transfer (LET) exposure. Human peripheral blood lymphocytes were irradiated using carbon ions (LET: 34.6 keV mu m(-1)), and the chromosome aberrations induced were analyzed using both a conventional colcemid block method and a calyculin A induced premature chromosome condensation (PCC) method. At a lower dose range (0-4 Gy), the measured dicentric (dics) and centric ring chromosomes (cRings) provided reasonable dose information. At higher doses (8 Gy), however, the frequency of dics and cRings was not suitable for dose estimation. Instead, we found that the number of Giemsa-stained drug-induced G2 prematurely condensed chromosomes (G2-PCC) can be used for dose estimation, since the total chromosome number (including fragments) was linearly correlated with radiation dose (r = 0.99). The ratio of the longest and the shortest chromosome length of the drug-induced G2-PCCs increased with radiation dose in a linear-quadratic manner (r = 0.96), which indicates that this ratio can also be used to estimate radiation doses. Obviously, it is easier to establish the dose response curve using the PCC technique than using the conventional metaphase chromosome method. It is assumed that combining the ratio of the longest and the shortest chromosome length with analysis of the total chromosome number might be a valuable tool for rapid and precise dose estimation for victims of radiation accidents.

Production of EUV power with SECRAL

The high power EUV source is one of key issues in the development of EUV lithography which is considered to be the most promising technology among the next generation lithography. However neither DPP nor LPP seems to meet the requirements of the commercial high-volume product. Insufficiency of DPP and LPP motivate the investigation of other means to produce the EUV radiation required in lithography. ECR plasma seems to be one of the alternatives. In order to investigate the feasibility of ECR plasma as a EUV light source, the EUV power emitted by SECRAL was measured. A EUV power of 1.03W in 4 pi sr solid angle was obtained when 2000W 18GHz rf power was launched, and the corresponding CE was 0.5%. Considering that SECRAL is designed to produce very high charge state ions, this very preliminary result is inspiring. Room-temperature ECR plasma and Sn plasma are both in the planned schedule.

Production cross section of Th-236 in the interaction of U-238 with 60 MeV/u O-18 ions

The neutron-rich target-like isotope Th-236 has been produced in the U-238-2p multinucleon transfer reaction between a 60 MeV/u O-18 beam and natural U-238 targets. The activities of thorium were determined after radiochemical separation of Th from the mixture of uranium and reaction products. The Th-236 isotope was identified by the characteristic gamma-rays of 642.2, 687.6 and 229.6 keV. The production cross section of Th-236 was determined to be 250 +/- 50 mu b.

Production cross-section of Th-236 in the interaction of U-238 with 60MeV/u O-18 Ions

The neutron-rich target-like isotope Th-236 was produced in U-238-2p multinucleon transfer reaction between a 60MeV/u O-18 beam and nature U-238 targets. The thorium activities were radiochemically separated from the mixture of uranium and reaction products. The isotope Th-236 was identified by 642.2keV, 687.6keV and 229.6keV characteristic gamma-rays. The production cross section of Th-236 has been determined to be 250 +/- 50 mu b.

Synthesis of NaA zeolite membrane on a ceramic hollow fiber

NaA zeolite membrane was successfully synthesized on a ceramic hollow fiber with an outer diameter of 400 mum, a thickness of 100 mum and an average pore radius of 0.1 mum. The as-synthesized membranes were characterized by XRD, SEM as well as gas permeation. A continuous C NaA zeolite membrane formed after a three-stage synthesis. The membrane thickness was similar to5 mum. Gas permeation data indicated that a relatively high quality NaA zeolite membrane formed on the ceramic hollow fiber support. (C) 2003 Elsevier B.V. All rights reserved.

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.

长白山红松针阔叶混交林生态系统生产力的估算

利用LI-6400CO2分析系统测定了长白山红松针阔叶混交林生态系统土壤呼吸、乔木和灌木树干和枝条的呼吸、植物叶片光合与呼吸．同步监测森林小气候气象因子,建立土壤、树干、叶片与气象因子间的模型．根据红松针阔叶混交林植被群落特性,估算红松针阔叶混交林森林生态系统不同组分CO2通量．利用涡度相关技术监测红松针阔叶混交林净生态系统交换量．探讨温度、光合有效辐射对森林生态系统CO2通量的影响．通过分析发现,在当年的气候条件下,该森林净生态系统交换量主要受土壤呼吸和叶片光合的影响．红松针阔叶混交林净生态系统交换量全年变化范围在-4．67～13．80μmol·m-2·s-1．该森林生态系统CO2通量在冬季和夏季里平均分别为-2．0和3．9μmol·m-2·s-1(24 h平均值)．乔木、灌木和草本的初级生产力分别占阔叶红松林总初级生产力的89．7％,3．5％,6．8％．土壤呼吸是森林生态系统中最主要的CO2排放源,约占红松针阔叶混交林生态系统CO2排放的69．7％,植物叶片和枝干分别占15．2％和15．1％．在生长季和非生长季中红松针阔叶混交林净生态系统交换量分别占全年CO2通量的56．8％和43．2％．自养呼吸占总初级生产力的比值(Ra:GPP)为0．52(NPP:GPP=0．48)．森林生态系统地下当年碳积累量占总初级生产力的52％．土壤呼吸占总初级生产力的60％．红松针阔叶混交林NPP为769．3 gC·m-2·a-1．该森林净生态系统交换量(NEE)为229．51 gC·m-2·a-1．涡度相关技术获得的该森林生态系统NEE低于箱式法获得的19．8％．