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A method for neutron-induced gamma spectra decomposition analysis based on Geant4 simulation

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Nuclear Science and Techniques 2022年第12期33卷 36-48页

作者： Wei Tang Jin-Gang Liang Yi Ge Qiong Zhang University of Electronic Science and Technology of China Chengdu 610000China Tsinghua University Beijing 10000China

In various monitoring and detection tools that use pulsed neutron generators as radiation sources,the gamma rays induced by the interaction with various nuclei at different stages of neutron transport can reflect information about the *** gamma rays are generated in two major interactions:inelastic scattering of fast neutrons and radiative capture of thermal neutrons,corresponding to the inelastic and capture gamma rays,***,the two types of gamma rays that reflect different properties of the medium are difficult to collect by normal detectors *** proportion of the two gamma rays needs to be solved for the separation of inelastic and capture ***,this study proposes an optimized spectra decomposition method to calculate the inelastic-to-capture ratio in the measured total gamma spectra based on the net inelastic and capture spectra obtained using the Geant4 *** the simulated data cannot reflect the energy resolution of the measured spectra,we introduce the Gaussian broadening function of the gamma detector while calculating the proportion of the spectra components,and achieve optimization of the proportion values and resolution parameters *** on the results,the total simulated spectra obtained by superimposing the broadened net inelastic and capture gamma spectra according to the calculated inelastic-to-capture ratio are in good agreement with their measured counterpart.

关键词： Neutron-induced gamma Geant4 spectra analysis

Residual Phase Noise and Time Jitters of Single-Chip Digital Frequency Dividers

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Journal of Electronic Science and Technology 2015年第3期13卷 264-268页

作者： Lu-Lu Yan Sen Meng Wen-Yu Zhao Wen-Ge Guo Hai-Feng Jiang Shou-Gang Zhang the Key Laboratory of Time and Frequency Standards National Time Service Center (NTSC) Chinese Academy of Sciences the School of Science Xi’an Shiyou University the Key Laboratory of Time and Frequency Standards National Time Service Center Chinese Academy of Sciences

In this paper, we demonstrate the residual phase noise of a few microwave frequency dividers which usually limit the performance of frequency synthesizers. In order to compare these dividers under different operation frequencies, we calculate additional time jitters of these dividers by using the measured phase noise. The time jitters are various from -0.1 fs to 43 fs in a bandwidth from 1 Hz to 100 Hz in dependent of models and operation frequencies. The HMC series frequency dividers exhibit outstanding performance for high operation frequencies, and the time jitters can be sub-fs. The time jitters of SP8401, MC10EP139, and MC100LVEL34 are comparable or even below that of HMC series for low operation frequencies.

关键词： Frequency divider phase noise spectra analysis time jitter

A Preliminary Study of the Types of Volcanic Earthquakes and Volcanic Activity at the Changbaishan Tianchi Volcano

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Earthquake Research in China 2006年第3期20卷 286-294页

作者： Ming Yuehong Su Wei Fang Lihua Institute of Geophysics China Earthquake Administration Beijing 100081 China

Since 2002, a significant increase in seismicity, obvious ground deformation and geochemical anomalies have been observed in the Changbaishan Tianchi volcanic area. A series felt earthquakes occur near the caldera, causing great influence to society. In this paper, the types of volcanic earthquakes recorded by the temporal seismic network since 2002 have been classified by analyzing the spectrum, time-frequency characteristics and seismic waveforms at different stations. The risk of volcano eruptions was also estimated. Our results show that almost all earthquakes occurring in Tianchi volcano are volcanic-tectonic earthquakes. The low frequency seismic waveforms observed at a few stations may be caused by local mediums, and have no relation with long-period events. Although the level of seismicity increased obviously and earthquake swarms occurred more frequently than before, we considered that the magma activity is still in its early stage and the eruption risk of Changbaishan Tianchi volcano is still low in the near future.

关键词： Changbaishan Volcano Earthquake types Volcano-tectonic earthquake spectra analysis