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CDEX-1 1 kg point-contact germanium detector for low mass dark matter searches

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Chinese Physics C 2013年第12期37卷 58-64页

作者：康克军岳赛吴呈城程建平李元景白杨毕勇常建平陈楠陈宁陈庆豪陈云华庄又澄邓智杜强宫辉郝喜庆何庆驹胡鑫洄黄瀚雄黄腾锐江灏李浩斌李荐民李金李军李霞李新颖李学潜李玉兰廖恒毅林枫凯林欣德刘书魁吕岚春马豪毛绍基覃建强任杰任婧阮锡超申满斌 Lakhwinder SINGH Manoj Kumar SINGH Arun Kumar SOMA 苏健唐昌建曾昭雄王继敏王力王青王子敬吴世勇吴蔚吴玉成幸浩洋徐音薛涛杨丽桃杨松纬易难喻纯旭于昊余训臻曾雄辉曾志张岚张蕴华赵明刚赵伟钟苏宁周祖英朱敬军朱维彬朱学洲朱忠华 Tsinghua University Nankai University Sichuan University NUCTECH company yalong river hydropower development company Institute of Physics AS China Institute of Atomic Energy Department of Physics Banaras Hindu University

The CDEX collaboration has been established for direct detection of light dark matter particles, using ultra-low energy threshold point-contact p-type germanium detectors, in China JinPing underground Laboratory （CJPL）. The first 1 kg point-contact germanium detector with a sub-keV energy threshold has been tested in a passive shielding system located in CJPL. The outputs from both the point-contact P＋ electrode and the outside N＋ electrode make it possible to scan the lower energy range of less than 1 keV and at the same time to detect the higher energy range up to 3 MeV. The outputs from both P＋ and N＋ electrode may also provide a more powerful method for signal discrimination for dark matter experiment. Some key parameters, including energy resolution, dead time, decay times of internal X-rays, and system stability, have been tested and measured. The results show that the 1 kg point-contact germanium detector, together with its shielding system and electronics, can run smoothly with good performances. This detector system will be deployed for dark matter search experiments.

关键词： CDEX point-contact germanium detector dark matter CJPL

Measurement of cosmic ray flux in the China JinPing underground laboratory

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Chinese Physics C 2013年第8期37卷 45-49页

作者：吴昱城郝喜庆岳骞李元景程建平康克军陈云华李金李荐民李玉兰刘书魁马豪任金宝申满斌王继敏吴世勇薛涛易难曾雄辉曾至朱忠华 Department of Engineering Physics Tsinghua University Key Laboratory of Particle and Radiation Imaging Tsinghua University Ministry of Education yalong river hydropower development company School of Physical Science and Technology Sichuan University

The China JinPing underground Laboratory （CJPL） is the deepest underground laboratory running in the world at present. In such a deep underground laboratory, the cosmic ray flux is a very important and necessary parameter for rare-event experiments. A plastic scintillator telescope system has been set up to measure the cosmic ray flux. The performance of the telescope system has been studied using the cosmic rays on the ground laboratory near the CJPL. Based on the underground experimental data taken from November 2010 to December 2011 in the CJPL, which has an effective live time of 171 days, the cosmic ray muon flux in the CJPL is measured to be （2.0±0.4）×10^-10/（cm2.s）. The ultra-low cosmic ray background guarantees an ideal environment for dark matter experiments at the CJPL.

关键词： CJPL cosmic ray flux deep underground laboratory dark matter

Effects of freezing-thawing on the engineering performance of core wall soil materials of a dam in the process of construction

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Journal of Mountain Science 2020年第11期17卷 2840-2852页

作者： REN Xiu-ling YU Qi-hao ZHANG Gui-ke YUE Pan LIU En-long ZHANG Zhen-yu YOU Yan-hui State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China yalong river hydropower development company LtdChengdu 610065China State Key Laboratory of Hydraulics and Mountain river Engineering College of Water Resources and HydropowerSichuan UniversityChengdu 610065China

The construction of water conservancy projects in cold regions experiences freezing-thawing cycles,which can greatly change the engineering properties of soil and have a significant impact on the construction of *** hydropower Station(LHS),is a controlling station with the largest installed capacity among the 7 middle reach projects in the yalong river,the secondary tributary of the Yangtze *** is located in a seasonally frozen soil *** on the measured data of air and ground temperature in winter in the dam core wall,the freezing-thawing variation of gravelly soil and contact clay during the filling process of the core wall are compared and analyzed,then the main impact factors of the freezing-thawing variation of soils are *** results show that under the influence of air temperature,soil freezes unidirectionally from ground surface downward and deepens gradually,and the thawing processes are different at the aspects of thawing direction and *** temperature and physical properties of soil including soil type,moisture content and dry density affect the freezingthawing processes of *** the impact of engineering construction is more remarkable than natural *** engineering construction affects soil temperature and freezing-thawing process by controlling the initial temperature of soil,the speed and duration of the technological conversion of paving,compaction,and the length of placed duration at *** to the long placed duration of soil with the slow construction method,the initial temperature of soil gradually reduces,the heat transfer process inside soil is *** the internal heat of soil releases,the decreasing rate of ground temperature of soil at different depths is fast and the frozen depth *** due to the short placed duration of soil with the rapid construction process,the initial temperature of soil is high,high internal heat of soil is supplied every day,and the heat transfer process in

关键词： Lianghekou hydropower Station(LHS) Gravelly soil Contact clay Freezing-thawing variation Impact factors

First results on ^(76)Ge neutrinoless double beta decay from CDEX-1 experiment

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Science China(Physics,Mechanics & Astronomy) 2017年第7期60卷 53-59页

作者： Li Wang Qian Yue KeJun Kang JianPing Cheng YuanJing Li TszKing Henry Wong ShinTed Lin JianPing Chang JingHan Chen QingHao Chen YunHua Chen Zhi Deng Qiang Du Hui Gong Li He QingJu He JinWei Hu HanXiong Huang TengRui Huang LiPing Jia Hao Jiang HauBin Li Hong Li JianMin Li Jin Li Jun Li Xia Li XueQian Li YuLan Li FongKay Lin ShuKui Liu Hao Ma JingLu Ma XingYu Pan Jie Ren XiChao Ruan ManBin Shen Vivek Sharma Lakhwinder Singh Manoj Kumar Singh Manoj Kumar Singh Arun Kumar Soma ChangJian Tang WeiYou Tang ChaoHsiung Tseng JiMin Wang Qing Wang ShiYong Wu YuCheng Wu HaoYang Xing Yin Xu Tao Xue LiTao Yang SongWei Yang Nan Yi ChunXu Yu HaiJun Yu WeiHe Zeng XiongHui Zeng Zhi Zeng Lan Zhang YunHua Zhang MingGang Zhao Wei Zhao JiFang Zhou ZuYing Zhou JingJun Zhu WeiBin Zhu ZhongHua Zhu Key Laboratory of Particle and Radiation Imaging (Ministry of Education) and Department of Engineering Physics Tsinghua University Institute of Physics Academia Sinica School of Physical Science and Technology Sichuan University NUCTECH company yalong river hydropower development company Department of Nuclear Physics China Institute of Atomic Energy School of Physics Nankai University Department of Physics Banaras Hindu University

We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.

关键词： neutrinoless double beta decay CDEX point-contact germanium detector 76Ge isotope

Deterministic processes dominate microbial community assembly in artificially bred Schizothorax wangchiachii juveniles after being released into wild

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Integrative Zoology 2023年第6期18卷 1072-1088页

作者： Liangliang XU Baowen ZHANG Fenglin LIU Zesong WANG Wenxue GAO Weixiong GAN Hanxi CHEN Zhaobin SONG Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education College of Life SciencesSichuan UniversityChengduChina yalong river hydropower development company Ltd.ChengduChina Observation and Research Station of Sichuan Province of Fish Resources and Environment in Upper Reaches of the Yangtze river College of Life SciencesSichuan UniversityChengduChina

Fish artificial breeding and release is an important method to restore wild populations of endemic fish species around the *** wangchiachii(SW)is an endemic fish in the upper Yangtze river and is one of the most important species for the artificial breeding and release program implemented in the yalong river drainage system in *** is unclear how artificially bred SW adapts to the changeable wild environment post-release,after being in a controlled and very different artificial ***,the gut samples were collected and analyzed for food composition and microbial 16S rRNA in artificially bred SW juveniles at day 0(before release),5,10,15,20,25,and 30 after release to the lower reaches of the yalong *** results indicated that SW began to ingest periphytic algae from the natural habitat before day 5,and this feeding habit is gradually stabilized at day *** to release,Fusobacteria are the dominant bacteria in the gut microbiota of SW,while Proteobacteria and Cyanobacteria generally are the dominant bacteria after *** results of microbial assembly mechanisms illustrated that deterministic processes played a more prominent role than stochastic processes in the gut microbial community of artificially bred SW juveniles after releasing into the ***,the present study integrates the macroscopic and microscopic methods to provide an insight into the food and gut microbial reorganization in the released *** study will be an important research direction to explore the ecological adaptability of artificially bred fish after releasing into the wild.

关键词： artificial release deterministic processes gut microbes network complexity Schizothorax wangchiachii

Creep characteristics and constitutive model for frozen mixed soils

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Journal of Mountain Science 2021年第7期18卷 1966-1976页

作者： SONG Bing-tang LIU En-long SHI Zhao-yun WANG Pan YU Qi-hao Northwest Institute of Eco-Environment and Resources State Key Laboratory of Frozen Soil EngineeringChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Hydraulics and Mountain river Engineering College of Water Resources and HydropowerSichuan UniversityChengdu 610065China yalong river hydropower development company Ltd. Chengdu 610051China

The uniform settle caused by the permafrost creep is still the primary problem of engineering construction in cold *** investigate the creep characteristics of frozen soils mixed with silty clay and coarse-grained sand,several triaxial creep tests of frozen mixed soils under different conditions(temperature,confining pressure,coarse-grained particle content) were performed,and the effects of the temperature,confining pressure and coarse particle content on the creep characteristics of frozen mixed soils were also *** results of the experiments indicated that when the confining pressure was low,the specimen exhibited an attenuation creep under a low-stress level(0.4-0.7) and a non-attenuation creep under a high-stress level(0.7-0.9).In contrast,when the confining pressure was high,the specimen had both initial and stable creep stages,but no the accelerated creep *** higher the content of coarse grains,the shorter the stable creep stage,and the easier to enter the accelerated creep stage for the ***,the long-term strength of frozen soils decreased with an increase in the content of coarse ***,a newly improved Nishihara model was proposed to consider both the hardening effect and damage effect by introducing both the hardening and damage variables,which can model the entire creep process of frozen soils modeled relatively *** was found that with the increasing content of coarse particle,both the strengthening and damaged effects in the creep process are reduced。

关键词： Frozen mixed soil Creep Hardening and damage Constitutive model

Dynamic mechanical characteristics of deep Jinping marble in complex stress environments

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 630-644页

作者： Chendi Lou Heping Xie Ru Zhang Hai Ren Hao Luo Kun Xiao Yuan Peng Qiang Tan Li Ren Institute for Disaster Management and Reconstruction Sichuan UniversityChengdu610207China College of Water Resource&hydropower Sichuan UniversityChengdu610065China MOE Key Laboratory of Deep Earth Science&Engineering Sichuan UniversityChengdu610065China yalong river hydropower development company Ltd.Chengdu610051China (Chongqing)International Engineering Technology company Ltd.Chongqing401121China

To reveal the dynamic mechanical characteristics of deep rocks,a series of impact tests under triaxial static stress states corresponding to depths of 300-2400 m were *** results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of *** sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth,indicating that producing penetrative cracks in deep environments is more difficult when damage *** dynamic strength shows a tendency to decrease and then increase slightly,but decreases sharply *** demonstrates a similar trend as that of strength,whereas reflectivity indicates the opposite ***,two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory(CJPL)were proposed for deep *** first critical depth is 600-900 m,beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease,causing instability of surrounding rocks under axial stress *** second one lies at 1500-1800 m,where the wave impedance and dynamic strength of deep surrounding rocks drop sharply,and the dissipation energy presents a negative *** suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types,depending on the second critical depth.

关键词： Rock mechanics Split-Hopkinson pressure bar Coupled static‒dynamic loading Different depths Holmquist-Johnson-Cook(HJC)model

3-D fracture network dynamic simulation based on error analysis in rock mass of dam foundation

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Journal of Central South University 2018年第4期25卷 919-935页

作者： ZHONG Deng-hua WU Han WU Bin-ping ZHANG Yi-chi YUE Pan The State Key Laboratory of Hydraulic Engineering Simulation and Safety(Tianjin University) Tianjin 300072China yalong river hydropower development company Ltd.Chengdu 610051China

Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam *** the aim of reducing deviation between fracture network model and measured data,a 3-D fracture network dynamic modeling method based on error analysis was ***,errors of four fracture volume density estimation methods(proposed by ODA,KULATILAKE,MAULDON,and SONG)and that of four fracture size estimation methods(proposed by EINSTEIN,SONG and TONON)were respectively compared,and the optimal methods were ***,error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error(RAE).On this basis,the downhill simplex method was used to build the dynamic modeling method,which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error ***,the 3-D fracture network model could be obtained which meets the *** proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.

关键词： rock mass of dam foundation 3-D fracture network dynamic simulation fractal dimension error analysis relative absolute error(RAE) downhill simplex method

Engineering rock mechanics practices in the underground powerhouse at JinpingⅠhydropower station

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第5期8卷 640-650页

作者： Aiqing Wu Jimin Wang Zhong Zhou Shuling Huang Xiuli Ding Zhihong Dong Yuting Zhang Key laboratory ofGeotechnical Mechanics and Engineering of the Ministry ofWaterResources Yangtze RiverScientificResearch InstituteWuhan430010China yalong river hydropower development company Ltd.Chengdu610051China HydroChina Chengdu Engineering Corporation Ltd.Chengdu610072China

Based on the analyses of data obtained from the underground powerhouse at Jinping I hydropower station, a comprehensive review of engineering rock mechanics practice in the underground powerhouse is first conducted. The distribution of strata, lithology, and initial geo-stress, the excavation process and corresponding rock mass support measures, the deformation and failure characteristics of the surrounding rock mass, the stress characteristics of anchorage structures in the cavern complex, and numerical simulations of surrounding rock mass stability and anchor support performance are presented. The results indicate that the underground powerhouse of Jinping I hydropower station is characterized by high to extremely high geo-stresses during rock excavation. Excessive surrounding rock mass deformation and high stress of anchorage structures, surrounding rock mass unloading damage, and local cracking failure of surrounding rock masses, etc., are mainly caused by rock mass excavation. Deformations of surrounding rock masses and stresses in anchorage structures here are larger than those found elsewhere： 20% of extensometers in the main powerhouse record more than 50 mm with the maximum at around 250 mm observed in the downstream sidewall of the transformer hall. There are about 25% of the anchor bolts having recorded stresses of more than 200 MPa. Jinping I hydropower plant is the first to have an underground powerhouse construction conducted in host rocks under extremely high geo-stress conditions, with the ratio of rock mass strength to geo-stress of less than 2.0. The results can provide a reference to underground powerhouse construction in similar geological conditions.

关键词： Underground powerhouse High geo-stress Rock mechanics Rock mass stability Engineering practice