School of Nuclear Science and Technology, University of South China, Hengyang 421001, China;Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;[单健; Xiao De-Tao; Wei Nan-Nan; Zhou Qing-Zhi] 南华大学核科学技术学院;[Liu Wei; Lin Jun; Wang Guang-Hua] 中国科学研究院上海应用物理研究所
[Liu Wei] Chinese Acad Sci, Shanghai Inst Appl Phys, Shanghai 201800, Peoples R China.;Shanghai Institute of Applied Physics, Chinese Academy of Sciences, China
Atmospheric aerosol;Daughter products of radon;Residence time
通过研究大气颗粒物中~(222)Rn子体活度比与颗粒物平均寿命之间的关系,建立了基于活度比估算大气颗粒物滞留时间(residence time of atmospheric aerosol,RTAA)的方法,并在相对理想条件下进行了实验验证.当氡室浓度稳定为1.816 kBq/m~3时,由214Bi/214Pb活度比计算出的RTAA为112.17 min,与氡室的平均换气时间(104.17 min)相当,表明大气颗粒物中同一衰变链上的放射性核素活度比(如~(214)Bi/~(214)Pb, ~(210)Bi/~(210)Pb或~(210)Po/~(210)Pb)可以用于估算RTAA.
Chinese Physics Letters,2015年32(3): 032901-1-032901-4 ISSN：0256-307X
School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China;School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China;Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China;LWD Logging Center, China Petroleum Logging, CO. LTD., Xi'an, 710000, China
[Hu Bi-Tao] Lanzhou Univ, Sch Nucl Sci & Technol, Lanzhou 730000, Peoples R China.;School of Nuclear Science and Technology, Lanzhou University, Lanzhou, China
A detector for fast neutrons based on a 10 × 10 cm~2 triple gas electron multiplier (GEM) device is developed and tested. A neutron converter, which is a high density polyethylene (HDPE) layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium (DT, 14 MeV), deuterium-deuterium (DD, 2.45 MeV), and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton (GEM material), and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented.
Journal of Environmental Sciences,2019年82(08):155-168 ISSN：1001-0742
[Xu, Zhiyou; Wei, Nannan] School of Nuclear Science and Technology, University of South China, Hengyang 421001, China;[Wang, Guanghua; Liu, Wei; Wei, Nannan] Department of Nuclear Reactor Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China;[Liu, Junwen] Institute for Environmental and Climate Research, Jinan University, Guangzhou 510632, China;[Zhuoga, Deqing] Meteorological Service Center of Tibet Autonomous Region Meteorological Bureau, Lhasa 850000, China;[Xiao, Detao] School of Nuclear Science and Technology, University of South China, Hengyang 421001, China. Electronic address: firstname.lastname@example.org
[Xiao, Detao] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Yao, Jian] Chinese Acad Sci, Shanghai Inst Appl Phys, Dept Nucl Reactor Engn, Shanghai 201800, Peoples R China.;School of Nuclear Science and Technology, University of South China, Hengyang, China
To understand the physical and chemical characteristics, particle size distribution and sources of size-separated aerosols in Lhasa, which is located on the Tibetan Plateau (TP), six sizes of aerosol samples were collected in Lhasa in 2014. Ca(2+), NH4(+), NO3(-), SO4(2-) and Cl(-) were the dominant ions. The ratio of cation equivalents (CE) to anion equivalents (AE) for each particle size segment indicated that the atmospheric aerosols in Lhasa were alkaline. SO4(2-) and NO3(-) could be neutralized by Ca(2+), but could not be neutralized by NH4(+), according to the [NH4(+)]/[NO3(-)+SO4(2-)] and [Ca(2+)]/[NO3(-)+SO4(2-)] ratios. Mobile sources were dominant in PM0.95-1.5, PM1.5-3 and PM3-7.2, while stationary sources were dominant in the other three size fractions according to the [NO3(-)]/[SO4(2-)] ratios. The particle size distribution of all water-soluble ions during monsoon and non-monsoon periods was characterized by a bimodal distribution due to the different sources and formation mechanisms, and it was revealed that different ions had different sources in different seasons and different particle size segments by combining particle size distribution with correlation analysis. Source analysis of aerosols in Lhasa was performed using the Principal component analysis (PCA) for the first time, which revealed that combustion sources, motor vehicle exhaust, photochemical reaction sources and various types of dust were the main sources of Lhasa aerosols. Furthermore, Lhasa's air quality was also affected by long-distance transmission, expressed as pollutants from South Asia and West Asia, which were transmitted to Lhasa according to backward trajectory analysis.