检索结果-南通市图书馆

L-Shell Ionization Cross section Measurements of Dysprosium and Samarium by Low-Energy Electron Impact

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第9期22卷 2244-2247页

作者：勾成俊吴章文杨代伦何福庆彭秀峰安竹罗正明 Key Laboratory of radiation Physics and Technology of the Ministry of Education Sichuan University Chengdu 610064 Institute of Nuclear Science and Technology Sichuan University Chengdu 610064

The Lα, Lβ and Lγ x-ray production cross sections of Dy and Sm by electron impact are measured at energies from near threshold to tens of keV. In the experiments, thin targets with thick substrates are used. Meanwhile, the electron transport bipartition model is used to eliminate the influence of electrons reflected from the thick substrates on measurements. The measured x-ray production cross sections are also compared with the theoretical predictions by Gryzinski and McGuire.

关键词： IMPROVED BIPARTITION MODEL TRANSPORT ATOMS

Fine structure of K_3C_(60) photoionization cross-section oscillations

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2009年第11期33卷 991-995页

作者：李宏年应理建倪敬付李刚王鹏奎热西.易卜拉欣钱海杰 Department of Physics Zhejiang University Laboratory of Synchrotron radiation Institute of High Energy Physics Chinese Academy of Sciences

The synchrotron radiation angle-resolved photoemission data of K3C60 single crystal film are analyzed, aiming at the photoionization cross-sections of the LUMO, HOMO and HOMO-1 bands in low photon energy region （14.5--27.5 eV）. Many fine structures of the HOMO/HOMO-1 intensity ratios are observed, which support the general validity of a quantum chemistry model. However, the experimental data and the theoretical results have some disagreement in the energy positions and magnitudes of the fine structures, and the disagreement is more outstanding than the case of pure C60. So the photoemission data of K3C60 afford valuable experimental reference to further theoretical developments. The LUMO cross-section data, which cannot be discussed with the quantum chemistry description due to strong solid state effects, are also reported for further studies.

关键词： photoionization cross-section fine structure K3C60

Characteristics of secondary inorganic aerosol and sulfate species in size-fractionated aerosol particles in Shanghai

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2014年第5期26卷 1040-1051页

作者： Shilei Long Jianrong Zeng Yan Li Liangman Bao Lingling Cao Ke Liu Liang Xu Jun Lin Wei Liu Guanghua Wang Jian Yao Chenyan Ma Yidong Zhao Shanghai Institute of Applied Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Synchrotron radiation Laboratory Institute of High Energy Physics Chinese Academy of Sciences

Sulfate, nitrate and ammonium （SNA） are the dominant species in secondary inorganic aerosol, and are considered an important factor in regional haze formation. Size-fractionated aerosol particles for a whole year were collected to study the size distribution of SNA as well as their chemical species in Shanghai. SNA mainly accumulated in fine particles and the highest average ratio of SNA to particulate matter （PM） was observed to be 47% in the fine size fraction （0.49-0.95 ~tm）. Higher sulfur oxidation ratio and nitrogen oxidation ratio values were observed in PM of fine size less than 0.95 ~tm. Ion balance calculations indicated that more secondary sulfate and nitrate would be generated in PM of fine size （0.49-0.95 p.m）. Sulfur K-edge X-ray absorption near-edge structure （XANES） spectra of typical samples were analyzed. Results revealed that sulfur mainly existed as sulfate with a proportion （atomic basis） more than 73% in all size of PM and even higher at 90% in fine particles. Sulfate mainly existed as （NH4）2SO4 and gypsum in PM of Shanghai. Compared to non-haze days, a dramatic increase of （NH4）2SO4 content was found in fine particles on haze days only, which suggested the promoting impact of （NH4）2SO4 on haze formation. According to the result of air mass backward trajectory analysis, more （NH4）2SO4 would be generated during the periods of air mass stagnation. Based on XANES, analysis of sulfate species in size-fractionated aerosol particles can be an effective way to evaluate the impact of sulfate aerosols on regional haze formation.

关键词： sulfate particulate matter XANES

Investigation on natural radionucildes levels in multiple media in bone-coal mine areas of five provinces

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2005年第4期16卷 244-248页

作者： KONG Ling-Li ZHANG Liang LI Ying YE Ji-Da JIANG Shan SHI Jin-Hua WU Zong-Mei Wuhan Academy of Environmental Science Wuhan 430015 Environmental Monitoring Center Station of Hunan Province Changsha 410004 Environmtental Monitoring Center Station of Jiangxi Province Nanchang 330029 Enviromnental radiation Monitoring Station of Zhejiang Province Han gzhou 310012 Environmental radiation Surveillance Station of Anhui Province Hefei 230061

This paper reports methods and results of the investigation of natural radionuclides levels in multiple me-dia in the bone-coal mine areas in Hubei, Hunan, Jiangxi, Zhejiang, and Anhui Provinces. In the studied bone-coal mine areas, the specific activities of 238U and 226Ra in the soil samples were 0.37 and 0.24 Bq/g, respectively; the spe-cific activities of 226Ra in the samples of bone-coal, bone-coal cinder and bone-coal cinder brick (BCCB) were 1.3, 1.4 and 0.9 Bq/g, respectively. In the water samples collected from the bone-coal mine areas, the average concentra-tions of natural uranium and 226Ra were 33μg/L and 58 mBq/L, respectively, while in the water samples collected from outside the bone-coal mine areas, they were 3.4μg/L and 45 mBq/L, respectively. In addition, the specific activi-ties of 238U and 226Ra in air aerosol samples from the bone-coal mine areas were 0.6 and 0.5 mBq/m3, respectively.

关键词：骨煤放射性等级 BCCB 环境影响

Applications of an AMSR-E RFI Detection and Correction Algorithm in 1-DVAR over Land

在线全文

学校读者我要写书评

暂无评论

Journal of Meteorological Research 2014年第4期28卷 645-655页

作者：吴莹翁富忠 Key Laboratory for aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science & Technology School of Atmospheric Physics Nanjing University of Information Science & Technology NOAA/NESDIS/Center for Satellite Application and Research College ParkMD 20742 USA

Land retrievals using passive microwave radiometers are sensitive to small fluctuations in land brightness temperatures. As such, the radio-frequency interference （RFI） signals emanating from man-made microwave radiation transmitters can result in large errors in land retrievals. RFI in C-and X-band channels can con-taminate remotely sensed measurements, as experienced with the Advanced Microwave Scanning Radiometer （AMSR-E） and the WindSat sensor. In this work, applications of an RFI detection and correction algorithm in retrieving a comprehensive suite of geophysical parameters from AMSR-E measurements using the one-dimensional variational retrieval （1-DVAR） method are described. The results indicate that the values of retrieved parameters, such as land skin temperature （LST）, over these areas contaminated by RFI are much higher than those from the global data assimilation system （GDAS） products. The results also indicate that the differences between new retrievals and GDAS products are decreased evidently through taking into account the RFI correction algorithm. In addition, the convergence metric （χ2） of 1-DVAR is found to be a new method for identifying regions where land retrievals are affected by RFI. For example, in those regions with much stronger RFI, such as Europe and Japan, χ2 of 1-DVAR is so large that convergence cannot be reached and retrieval results may not be reliable or cannot be obtained. Furthermore,χ2 also decreases with the RFI-corrected algorithm for those regions with moderate or weak RFI. The results of RFI detected byχ2 are almost consistent with those identified by the spectral difference method.

关键词： microwave remote sensing radio-frequency interference (RFI) AMSR-E 1-DVAR

Updating the CSNS injector linac to 250 MeV with superconducting double-spoke cavities

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2015年第3期39卷 71-76页

作者：李智慧傅世年 The Key Labratory of radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University Institute of High Energy Physics Chinese Academy of Sciences

In order to update the beam power from 100 kW to 500 kW in the China Spallation neutron source （CSNS） Phase II, one of the important measures is to replace the 80 m long beam transport line between the present 80 MeV linac injector and the rapid cycling synchrotron （RCS） to another kind of acceleration structure. In this paper, we proposed a scheme based on 324 MHz double-spoke superconducting cavities. Unlike the superconducting elliptical cavity and normal conducting coupled cavity linac （CCL） structure, the double-spoke cavity belongs to the TE mode structure and has a smaller transverse dimension compared with that of the TH mode one. It can work at base frequency as the drift tube Linac （DTL） section, so that the cost and complexity of the RF system will be much decreased, and the behaviors of the beam dynamics are also improved significantly because of the low charge density and larger longitudinal acceptance. Furthermore, because of the relatively longer interactive length between the charged particle and the electromagnetic field per cell, it needs relatively less cell numbers and it has larger velocity acceptance compared with the double frequency TH structures. The superconducting section consists of 14 periods, each of which includes 3 superconducting cavities encapsulated in one cryomodule and a doublet in room temperate. The general considerations on cavity and beam dynamics design are discussed and the main results are presented.

关键词： CSNS double-spoke cavity high current proton linac dynamic stability

Shielding calculation for the thickness of the SR facility safety shutter

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2006年第4期17卷 198-201页

作者： YU Zheng-Ping LUO Wen-Yun CHEN Tao Shanghai Applied radiation Institute Shanghai University Shanghai 201800 China Shanghai Institute of Applied Physics the Chinese Academy of Sciences Shanghai 201800 China

The safety shutter of the SR (synchrotron radiation) facility located at the front end of the facility is an in- dispensable component for radiation protection. Its thickness is decided by the gas bremsstrahlung produced in the SR facility storage ring by the interaction of electrons with the residual gas molecules in the vacuum chamber of the storage ring. In the calculation, the 3.5 GeV, 300 mA electron beam and a 15 m long insertion-device straight section (0.133 μ Pa) were taken into account, and the safety shutter was assumed to be located 12 m away from the end of the straight section. The EGSnrc code based on the Monte-Carlo method and empirical formulas were used, respectively, to calculate the thickness to satisfy the shielding requirement of the safety shutter at the front end of the SR facility, and the results were compared and the availability of EGSnrc was proved.

关键词：同步加速器辐射设备防火档板蒙特卡洛法厚度

Biological Dose Comparison between a Fixed RBE and a Variable RBE in SFO and MFO IMPT with Various Multi-Beams for Brain Cancer

在线全文

学校读者我要写书评

暂无评论

International Journal of Medical Physics, Clinical Engineering and radiation Oncology 2019年第1期8卷 32-45页

作者： Ryosuke Kohno Wenhua Cao Pablo Yepes Xuemin Bai Falk Poenisch David R. Grosshans Tetsuo Akimoto Radhe Mohan Medical Physics section National Institute of Radiological Sciences Chiba Japan Department of radiation Physics University of Texas MD Anderson Cancer Center Houston USA Division of radiation Oncology and Particle Therapy Exploratory Oncology Research & Clinical Trial Center National Cancer Center Hospital East Chiba Japan

IMPT plans with various multi-angle beams were planned by the Varian Eclipse treatment planning system for one case of brain cancer. Dose distributions for each plan, along with the associated linear energy transfer distributions, were recomputed using an in-house fast Monte Carlo dose calculator with a FRBE of 1.1 or with a previously published VRBE model. We then compared dosimetric parameters obtained by the VRBE with those obtained by the FRBE. Biological doses obtained by the VRBE for the clinical target volume in all plans were 1% - 2% larger than those obtained by the FRBE. The minimum dose obtained by the VRBE for the right optic nerve in the MFO IMPT with 4 fields was 70% larger than that obtained by the FRBE, but the difference was only 18.1 cGy (RBE). The difference in maximum dose for the right optic nerve in the MFO IMPT with 5 fields was less than 10.4%, but the difference was 131.8 cGy (RBE). The mean difference in maximum dose was less than 2% for all other organs at risk. We found that biological dose with the FRBE had any dose errors in IMPT with various multi-angle beams.

关键词： IMPT Monte Carlo Biological Dose Variable RBE

Growth of Ag nanocrystals on multiwalled carbon nanotubes and Ag-carbon nanotube interaction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第11期52卷 3215-3218页

作者： WANG ZhenXia LI XinNian REN CuiLan YONG ZhenZhong ZHU JianKang LUO WenYun FANG XiaoMing Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Shanghai Applied radiation Institute Shanghai UniversityShanghai 201800China

The experimental investigations on the interaction between Ag-nanocrystal particles (Ag-NCPs) and carbon nanotubes (CNTs) in Ag-nanocrystal particles/carbon nanotubes (Ag-NCPs/CNTs) hybrid structures were reported. The growth of Ag-NCPs on multiwalled carbon nanotubes (MWCNTs) was carried out by thermal evaporation deposition. High-resolution transmission electron microscopy and X-ray diffraction analyses revealed that Ag-NCPs had the crystal lattice feature of face-centered cube (fcc). The growth of Ag-NCPs on MWCNTs induced the cross-section deformation of MWCNT. The experimental results also showed that the synthesized Ag-NCPs/CNTs hybrid structure appeared as quasi-one dimensional nanowires containing the Ag-NCP/CNT hetero-junction. There was local cross-section deformation on MWCNTs at the interface of hetero-junction. These results involve the important topic about fundamental and practical studies for structure of MNCPs on CNTs and also find clues to further research of Ag nanocrystal growing on MWCNTs and related Ag-CNT interaction.

关键词： metal nanocrystal particles/carbon nanotubes hybrid structure Ag-nanocrystal particle Ag-NCP/CNT hetero-junction