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nuclear Science and Techniques 2017年第8期28卷 1-40页

作者： Xiaofeng Luo nu xu Institute of Particle Physics and Key Laboratory of Quark andLepton Physics (MOE) Central China Normal UniversityWuhan 430079 China Department of Physics and Astronomy University ofCalifomia Los Angeles CA 90095 USA nuclear Science Division Lawrence Berkeley NationalLaboratory Berkeley CA 94720 USA

Fluctuations of conserved quantities, such as baryon, electric charge, and strangeness number, are sensitive observables in relativistic heavy-ion collisions to probe the QCD phase transition and search for the QCD critical point. In this paper, we review the experimental measurements of the cumulants(up to fourth order) of event-byevent net-proton(proxy for net-baryon), net-charge and netkaon(proxy for net-strangeness) multiplicity distributions Au+Au collisions at sNN^(1/2) 7:7; 11:5; 14:5; 19:6; 27;39; 62:4; 200 Ge V from the first phase of beam energy scan program at the relativistic heavy-ion collider(RHIC). We also summarize the data analysis methods of suppressing the volume fluctuations, auto-correlations, and the unified description of efficiency correction and error *** on theoretical and model calculations, we will discuss the characteristic signatures of critical point as well as backgrounds for the fluctuation observables in heavy-ion collisions. The physics implications and the future secondphase of the beam energy scan(2019–2020) at RHIC will also be discussed.

关键词：高能重离子碰撞 QCD相变 RHIC 临界点守恒量波动搜索相对论重离子碰撞

An estimation model for the fragmentation properties of brittle rock block due to the impacts against an obstruction

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Journal of Mountain Science 2017年第6期14卷 1161-1173页

作者： HOU Tian-xing xu Qiang XIE Hong-qiang xu nu-wen ZHOU Jia-wen State Key Laboratory of Hydraulics and Mountain River Engineering Siehuan University Chengdu 610065 China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610059 China College of Water Resource and Hydropower Sichuan University Chengdu 610065 China

Mountain hazards with large masses of rock blocks in motion – such as rock falls, avalanches and landslides – threaten human lives and structures. Dynamic fragmentation is a common phenomenon during the movement process of rock blocks in rock avalanche, due to the high velocity and impacts against obstructions. In view of the energy consumption theory for brittle rock fragmentation proposed by Bond, which relates energy to size reduction, a theoretical model is proposed to estimate the average fragment size for a moving rock block when it impacts against an obstruction. Then, different forms of motion are studied, with various drop heights and slope angles for the moving rock block. The calculated results reveal that the average fragment size decreases as the drop height increases, whether for free-fall or for a sliding or rolling rock block, and the decline in size is rapid for low heights and slow for increasing heights in the corresponding curves. Moreover, the average fragment size also decreases as the slope angle increases for a slidingrock block. In addition, a rolling rock block has a higher degree of fragmentation than a sliding rock block, even for the same slope angle and block volume. Finally, to compare with others' results, the approximate number of fragments is estimated for each calculated example, and the results show that the proposed model is applicable to a relatively isotropic moving rock block.

关键词： Rock block Rock fragmentation Rock movement process Crushing work ratio Average fragment size

Event plane determination from the zero degree calorimeter at the cooling storage ring external-target experiment

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nuclear Science and Techniques 2023年第7期34卷 113-121页

作者： Li-Ke Liu Hua Pei Ya-Ping Wang Biao Zhang nu xu Shu-Su Shi Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan 430079China

The Cooling Storage Ring external-target experiment(CEE)spectrometer is used to study the nuclear matter created in heavy-ion collisions at√sNN=2.1-2.4 GeV with the aim to reveal the quantum chromodynamics phase structure in the high-baryon-density *** flow is considered an effective probe for evaluating the properties of media during high-energy nuclear *** of the main functions of the zero-degree calorimeter(ZDC),a subdetector system in the CEE,is to determine the reaction plane in heavy-ion *** step is crucial for measuring the collective flow and other reaction-plane-related *** this paper,we illustrate the procedures for event plane determination using the ***,isospin-dependent quantum molecular dynamics model-based predictions of the rapidity dependence of the directed and elliptical flows for p,d,t,3He,and 4He,produced in 2.1 GeV U+U collisions,are presented.

关键词： QCD phase structure Heavy-ion collisions Collective flow Reaction plane Zero-degree calorimeter

Classifier for centrality determination with zero-degree calorimeter at the cooling-storage-ring external-target experiment

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nuclear Science and Techniques 2023年第11期34卷 168-173页

作者： Biao Zhang Li‑Ke Liu Hua Pei Shu‑Su Shi nu xu Ya‑Ping Wang Key Laboratory of Quark and Lepton Physics(MOE)and Institute of Particle Physics Central China Normal UniversityWuhan 430079China

The zero-degree calorimeter(ZDC)plays a crucial role toward determining the centrality in the Cooling-Storage-Ring External-target Experiment(CEE)at the Heavy Ion Research Facility in Lanzhou.A boosted decision tree(BDT)multi-classification algorithm was employed to classify the centrality of the collision events based on the raw features from ZDC such as the number of fired channels and deposited *** data from simulated^(238)U+^(238)U collisions at 500 MeV∕u,generated by the IQMD event generator and subsequently modeled using the GEANT4 package,were employed to train and test the BDT *** results showed the high accuracy of the multi-classification model adopted in ZDC for centrality determination,which is robust against variations in different factors of detector geometry and *** study demon-strates the good performance of CEE-ZDC in determining the centrality in nucleus-nucleus collisions.

关键词： ZDC Boosted decision trees Multi-classification IQMD Centrality determination

Conceptual design of the HIRFL-CSR external-target experiment

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Science China(Physics,Mechanics & Astronomy) 2017年第1期60卷 65-71页

作者： LiMing Lu Hart Yi ZhiGang Xiao Ming Shao Song Zhang GuoQing Xiao nu xu Department of Physics Tsinghua University Beijing 100084 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Institute of Particle Physics Central China Normal University Wuhan 430079 China

One of the main purposes of heavy-ion collisions over a wide range of beam energy is to study the bulk properties of strong interaction matter and understand the Quantum Chromo Dy- namics （QCD） phase diagram, which carries wealth of infor- mation of the phase transition and the possibly existing criti- cal point of the strongly interacting system [1]. Such system exists as hadron gases at lower temperature and low baryon density. By increasing the temperature or density, the bound- ary of the hadrons disappears and the confined quarks move freely in the whole system.

关键词： MRPC Conceptual design of the HIRFL-CSR external-target experiment HIRFL TPC CSR

Excavation-induced microseismicity: microseismic monitoring and numerical simulation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第6期13卷 445-460页

作者： nu-wen xu Chun-an TANG Hong LI Feng DAI Ke MA Jing-dong SHAO Ji-chang WU State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and Hydropower Siehuan UniversityChengdu 610065China Institute o fRock Instability and Seismicity Research Dalian University of TechnologyDalian 116024China HydroChina Chengdu Engineering Corporation Chengdu 610072China China Guodian Dadu River Dagangshan Hydropower Development Co. Ltd.Ya'an 625409China

The volume of influence of excavation at the right bank slope of Dagangshan Hydropower Station, southwest China, is essentially determined from microseismic monitoring, numerical modeling and conventional measurements as well as in situ observations. Microseismic monitoring is a new application technique for investigating microcrackings in rock slopes. A micro- seismic monitoring network has been systematically used to monitor rock masses unloading relaxation due to continuous exca- vation of rock slope and stress redistribution caused by dam impoundment later on, and to identify and delineate the potential slippage regions since May, 2010. An important database of seismic source locations is available. The analysis of microseismic events showed a particular tempo-spatial distribution. Seismic events predominantly occurred around the upstream slope of 1180 m elevation, especially focusing on the hanging wall of fault XL316-1. Such phenomenon was interpreted by numerical modeling using RFPA-SRM code （realistic failure process analysis-strength reduction method）. By comparing microseismic activity and results of numerical simulation with in site observation and conventional measurements results, a strong correlation can he obtained between seismic source locations and excavation-induced stress distribution in the working areas. The volume of influence of the rock slope is thus determined. Engineering practices show microseismic monitoring can accurately diagnose magnitude, intensity and associated tempo-spatial characteristics of tectonic activities such as faults and unloading zones. The integrated technique combining seismic monitoring with numerical modeling, as well as in site observation and conventional surveying, leads to a better understanding of the internal effect and relationship between microseismic activity and stress field in the right bank slope from different perspectives.

关键词： Microseismic monitoring Rock slope numerical simulation Stability analysis Dagangshan Hydropower Station

Light nuclei production in Au+Au collisions at √^(s)NN=3 GeV from coalescence model

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Chinese Physics C 2023年第7期47卷 133-137页

作者：许月何熊宏许怒 Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

The nucleon coalescence model is one of the most popular theoretical models for light nuclei production in high-energy heavy-ion *** production of light nuclei d,t,^(3)He,and^(4)He is studied using the transport model JAM with a simplified afterburner coalescence at√^(s)NN=3 GeV Au+Au *** scan the cut-off of phenomenological coalescence parameters,i.e.,the relative spatial distance△R and momentum difference△P,for the formation of light nuclei by nucleon coalescence to reproduce the light nuclei pTspectra measured by the STAR *** results indicate a potential connection between the coalescence parameters and the binding energy as well as the diameter of these light nuclei.

关键词： nucleon coalescence light nuclei heavy-ion collision

Interaction between anti-shear galleries and surrounding rock in the right-bank slope of Dagangshan hydropower station

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Journal of Mountain Science 2017年第7期14卷 1428-1444页

作者： LI Lian-chong XING Ya-zi LIU Xing-zong MA Ke xu nu-wen ZHANG Fei School of Resources and Civil Engineering Northeastern University School of Civil Engineering Dalian University of Technology College of Water Resources and Hydropower Sichuan University

The fight-bank slope of the Dagangshan hydropower station located in Southwest China is a highly unloaded rock slope. Moreover, large-scale natural faults were detected in the slope body; some excavation-induced unloading fractures were discovered at elevations between lo75m and 1146m. Because of poor tectonic stability, the excavation work was suspended in September 2009, and six large- scale anti-shear galleries were employed to replace the weak zone in the slope body to reinforce the fight- bank slope. In this study, based on microseismic- monitoring technology and a numerical-simulation method, the stabilities of the slope with and without the reinforcement are analysed. An in-situ microseismic-monitofing system is used to obtain quantitative information about the damage location, extent, energy, and magnitude of the rocks. Thus, any potential sliding block in the fight-bank slope can be identified. By incorporating the numerical results along with the microseismic-monitoring data, the stress concentration is found to largely occur aroundthe anti-shear galleries, and the seismic deformation near the anti-shear galleries is apparent, particularly at elevations of 121o, 118o, 115o, and 112om. To understand the interaction mechanism between the anti-shear gallery and the surrounding rock, a 2D simulation of the potential damage process occurring in an anti-shear gallery is performed. The numerical simulation helps in obtaining additional information about the stress distribution and failure-induced stress re-distribution in the vicinity of the anti-shear galleries that cannot be directly observed in the field. Finally, the potential sliding surface of the right-bank slope is numerically obtained, which generally agrees with the spatial distribution of the in-situ monitored microseismic events. The safety factor of the slope reinforced with the anti-shear gallery increases by approximately 36.2%. Both the numerical results and microseismic data show that the anti-sh

关键词： Slope stability Microseismic monitoring numerical simulation Safety factor Anti-sheargallery

HBT Parameters and Space-Momentum Correlations in Relativistic Heavy-Ion Collisions

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Chinese Physics Letters 2001年第12期18卷 1568-1570页

作者： ZHANG Jing-Bo HUO Lei ZHANG Wei-Ning LI Xin-Hua xu nu LIU Yi-Ming Department of Physics Harbin Institute of TechnologyHarbin 150001 Center of Theoretical nuclear Physics National Laboratory of Heavy Ion AcceleratorLanzhou 730000 nuclear Science Division Lawrence Berkeley NationM LaboratoryCA 94720USA

Using the relativistic quantum molecular dynamics approach, with a correlation after-burner, the physics of the transverse momentum dependence of the Hanbury-Brown and Twiss parameters is studied for Au t Au, Si + Si and p + p collisions at the centre-of-mass energy v s=200 AGeV. The results indicate that the space-momentum correlations would affect such dependence in both heavy-ion and elementary collisions. The size parameters as a function of the transverse mass mt are sensitive to the degree of space-momentum correlations.

关键词： momentum transverse elementary

Beam-Energy Dependence of Directed Flow for Deuteron in Au+Au Collisions

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IMP & HIRFL Annual Report 2018年第1期 23-24页

作者： He Xionghong xu nu 不详

In heavy ion collisions,the directed flow v1 is considered to be sensitive to the equation of state(EoS)of QCD matter,since it reveals the pressure gradients at the early stage of the collision *** strength of the directed flow is characterized by the slope dv1/dy at mid-rapidity,which is obtained by a linear fit of v1 *** the referenced v1 study[1],distribution of dv1/dy for net-proton has been proposed as a signature of first order phase transition between hadronic matter and quark gluon plasma[2].

关键词： signature quark flow