In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulation...In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.展开更多
In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–...In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.展开更多
We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total ex...We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.展开更多
Machine learning(ML)is becoming a new paradigm for scientific research in various research fields due to its exciting and powerful capability of modeling tools used for big-data processing tasks.In this review,we firs...Machine learning(ML)is becoming a new paradigm for scientific research in various research fields due to its exciting and powerful capability of modeling tools used for big-data processing tasks.In this review,we first briefly introduce the different methodologies used in ML algorithms and techniques.As a snapshot of many applications by ML,some selected applications are presented,especially for low-and intermediate-energy nuclear physics,which include topics on theoretical applications in nuclear structure,nuclear reactions,properties of nuclear matter,and experimental applications in event identification/reconstruction,complex system control,and firmware performance.Finally,we present a summary and outlook on the possible directions of ML use in low-intermediate energy nuclear physics and possible improvements in ML algorithms.展开更多
As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels...As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels,broadcasts are carried out on multiple channels.Accordingly,channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting.In this paper,an anticollision selective broadcast protocol,called acSB,is proposed.A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel.Moreover,an anticollision scheme is adopted to avoid simultaneous rebroadcasts.Consequently,the proposed broadcast acSB outperforms other approaches in terms of smaller transmission delay,higher message reach rate and fewer broadcast collisions evaluated by simulations under different scenarios.展开更多
There are a number of puzzles concerning physics on the scale of nanometers to femtometers,including the neutron lifetime,the proton charge radius,and the possible existence of the deep Dirac level.With the developmen...There are a number of puzzles concerning physics on the scale of nanometers to femtometers,including the neutron lifetime,the proton charge radius,and the possible existence of the deep Dirac level.With the development of high-intensity laser technology,lasers today can induce extremely strong electromagnetic fields.Electrons in the deep shells of atoms as well as the atomic nucleus itself can be affected by these fields.This may provide a new experimental platform for studies of physical processes on the femto-to nanometer scale,where atomic physics and nuclear physics coexist.In this paper,we review possible new opportunities for studying puzzles on the femto-to nanometer scale using highintensity lasers.展开更多
The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in...The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1-10 keV electron equivalent energy, the total electron recoil background is found to be 4.9 × 10^(-5) kg^(-1) d^(-1) keV^(-1). The nuclear recoil background in the same region is 2.8 × 10^(-7) kg^(-1) d^(-1) keV^(-1). With an exposure of 5.6 ton-years, the sensitivity of Panda X-4 T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10^(-48) cm^2 at a dark matter mass of 40 Ge V/c^2.展开更多
Self-interacting dark matter(SIDM)is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies.Many SIDM models predict the existenc...Self-interacting dark matter(SIDM)is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies.Many SIDM models predict the existence of a light force carrier that mediates strong dark matter self-interactions.If the mediator couples to the standard model particles,it could produce characteristic signals in dark matter direct detection experiments.We report searches for signals of SIDM models with a light mediator using the full dataset of the PandaX-II experiment,basing on a total exposure of 132 tonne-days.No significant excess over background is found,and our likelihood analysis leads to a strong upper limit on the dark matter-nucleon coupling strength.We further combine the PandaX-II constraints and those from observations of the light element abundances in the early universe,and show that direct detection and cosmological probes can provide complementary constraints on dark matter models with a light mediator.展开更多
We report the dark matter search results obtained using the full 132 ton·day exposure of the PandaX-II experiment,including all data from March 2016 to August 2018.No significant excess of events is identified ab...We report the dark matter search results obtained using the full 132 ton·day exposure of the PandaX-II experiment,including all data from March 2016 to August 2018.No significant excess of events is identified above the expected background.Upper limits are set on the spin-independent dark matter-nucleon interactions.The lowest 90%confidence level exclusion on the spin-independent cross section is 2.2×10−46 cm2 at a WIMP mass of 30 GeV/c2.展开更多
Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe u...Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.展开更多
Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)...Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.展开更多
We study the phase structure of QCD matter in the framework of a multiphase transport model by implementing a strong local parton density fluctuation scenario. Our calculations on the beam energy dependence of net-pro...We study the phase structure of QCD matter in the framework of a multiphase transport model by implementing a strong local parton density fluctuation scenario. Our calculations on the beam energy dependence of net-proton high moment show that local parton density fluctuation only has a small effect. But it becomes important when all baryons are included. We then study the effect on elliptic flow and find that an enhanced local parton density fluctuation leads to a significant effect on protons but a small effect on pions. Our study provides a reference of transport dynamics on QCD phase transition phenomena and will be relevant for the upcoming phase II of the beam energy scan program at RHIC.展开更多
We report the Neutrino-less Double Beta Decay(NLDBD)search results from PandaX-II dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August 2018.W...We report the Neutrino-less Double Beta Decay(NLDBD)search results from PandaX-II dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August 2018.With NLDBD-optimized event selection criteria,we obtain a fiducial mass of 219 kg of natural xenon.The accumulated xenon exposure is 242 kg·yr,or equivalently 22.2 kg·yr of 136Xe exposure.At the region around 136Xe decay Q-value of 2458 keV,the energy resolution of PandaX-II is 4.2%.We find no evidence of NLDBD in PandaX-II and establish a lower limit for decay half-life of 2.1 ×10^23 yr at the 90%confidence level,which corresponds to an effective Majorana neutrino mass mββ<(1.4-3.7) eV.This is the first NLDBD result reported from a dual-phase xenon experiment.展开更多
Zpif’s law in the field of linguistics is tested in the nuclear disassembly within the framework of isospin dependent lattice gas model. It is found that the average cluster charge (or mass) of rank n in the charge (...Zpif’s law in the field of linguistics is tested in the nuclear disassembly within the framework of isospin dependent lattice gas model. It is found that the average cluster charge (or mass) of rank n in the charge (or mass) list shows exactly an inverse order to its rank, i.e., Zpif’s law appears at the phase transition temperature. This novel criterion shall be helpful in searching the nuclear liquid gas phase transition.展开更多
In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron backgroun...In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.展开更多
We present a systematic determination of the responses of PandaX-Ⅱ,a dual phase xenon time projection chamber detector,to low energy recoils.The electron recoil(ER) and nuclear recoil(NR) responses are calibrated,res...We present a systematic determination of the responses of PandaX-Ⅱ,a dual phase xenon time projection chamber detector,to low energy recoils.The electron recoil(ER) and nuclear recoil(NR) responses are calibrated,respectively,with injected tritiated methane or 220Rn source,and with 241Am-Be neutron source,in an energy range from 1-25 keV(ER) and 4-80 keV(NR),under the two drift fields,400 and 317 V/cm.An empirical model is used to fit the light yield and charge yield for both types of recoils.The best fit models can describe the calibration data significantly.The systematic uncertainties of the fitted models are obtained via statistical comparison to the data.展开更多
Ⅰ.INTRODUCTION The direct detection of dark matter particles,especially the weakly interacting massive particles(WIMPs),is being actively carried out by a couple of experiments worldwide[1].In recent years,the PandaX...Ⅰ.INTRODUCTION The direct detection of dark matter particles,especially the weakly interacting massive particles(WIMPs),is being actively carried out by a couple of experiments worldwide[1].In recent years,the PandaX-Ⅱ experiment located in the China Jinping Underground Laboratory(CJPL)[1-3],which uses the technology of dual phase liquid xenon time projection chambers(TPCs),has pushed the limits of the cross section between WIMPs and nucleons to a new level for most of the possible WIMP masses;other experiments of the same type are also being performed[4–10].展开更多
Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its c...Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods.The first method is fully based on Monte Carlo simulations.The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data.In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year,all these methods give a consistent result,i.e.,there are 1.15±0.57 neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.展开更多
基金This work was supported by the NSFC innovation group project(Grant No.11921006)the National Grand Instrument Project(Grant No.2019YFF01014402)+1 种基金the United States Department of Energy(Grant No.DE-FG03-93ER40773)the NNSA(Grant No.DENA0003841)(CENTAUR).The PIC simulations were carried out using the High-Performance Computing Platform of Peking University。
文摘In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.
文摘In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.
基金Supported in part by the National Key R&D Program of China(Grant No.2016YFA0400301)the National Natural Science Foundation of China(Grant Nos.11525522,11775141,and 11755001)+5 种基金the Double First Class Plan of the Shanghai Jiao Tong University,the China Postdoctoral Science Foundation(Grant No.2018M640036)the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,16DZ2260200,and 18JC1410200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education,for important supportsponsorship from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)the Hongwen Foundation in Hong Kongthe Tencent Foundation in China。
文摘We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.
基金supported by the National Natural Science Foundation of China(Grant Nos.11875070,11875323,12275359,11875125,12147219,U2032145,11705163,11790320,11790323,11790325,11975032,11835001,11935001,11890710,12147101,11835002,11705031,and 11961141003)the National Key R&D Program of China(Grant Nos.2018YFA0404404,2018YFA0404403,and 2020YFE0202001)+3 种基金the Continuous Basic Scientific Research Project(Grant No.WDJC-2019-13)the funding of China Institute of Atomic Energy(Grant No.YZ222407001301)the Leading Innovation Project of the China National Nuclear Corporation(Grant Nos.LC192209000701,and LC202309000201)the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030008)。
文摘Machine learning(ML)is becoming a new paradigm for scientific research in various research fields due to its exciting and powerful capability of modeling tools used for big-data processing tasks.In this review,we first briefly introduce the different methodologies used in ML algorithms and techniques.As a snapshot of many applications by ML,some selected applications are presented,especially for low-and intermediate-energy nuclear physics,which include topics on theoretical applications in nuclear structure,nuclear reactions,properties of nuclear matter,and experimental applications in event identification/reconstruction,complex system control,and firmware performance.Finally,we present a summary and outlook on the possible directions of ML use in low-intermediate energy nuclear physics and possible improvements in ML algorithms.
文摘As a fundamental operation in ad hoc networks,broadcast could achieve efficient message propagations.Particularl y in the cognitive radio ad hoc network where unlicensed users have different sets of available channels,broadcasts are carried out on multiple channels.Accordingly,channel selection and collision avoidance are challenging issues to balance the efficiency against the reliability of broadcasting.In this paper,an anticollision selective broadcast protocol,called acSB,is proposed.A channel selection algorithm based on limited neighbor information is considered to maximize success rates of transmissions once the sender and receiver have the same channel.Moreover,an anticollision scheme is adopted to avoid simultaneous rebroadcasts.Consequently,the proposed broadcast acSB outperforms other approaches in terms of smaller transmission delay,higher message reach rate and fewer broadcast collisions evaluated by simulations under different scenarios.
基金This work is supported by the National Nature Science Foundation of China(Grant No.11875191)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB16).
文摘There are a number of puzzles concerning physics on the scale of nanometers to femtometers,including the neutron lifetime,the proton charge radius,and the possible existence of the deep Dirac level.With the development of high-intensity laser technology,lasers today can induce extremely strong electromagnetic fields.Electrons in the deep shells of atoms as well as the atomic nucleus itself can be affected by these fields.This may provide a new experimental platform for studies of physical processes on the femto-to nanometer scale,where atomic physics and nuclear physics coexist.In this paper,we review possible new opportunities for studying puzzles on the femto-to nanometer scale using highintensity lasers.
基金supported by a 985-Ⅲ grant from Shanghai Jiao Tong University,the National Natural Science Foundation of China(Grant Nos.11435008,11455001,11505112,11525522,11775141,and 11755001)the Ministry of Science and Technology of China(Grant No.2016YFA0400301)+2 种基金the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,and 16DZ2260200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Educationsupported in part by the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)and Hongwen Foundation in Hong Kong
文摘The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1-10 keV electron equivalent energy, the total electron recoil background is found to be 4.9 × 10^(-5) kg^(-1) d^(-1) keV^(-1). The nuclear recoil background in the same region is 2.8 × 10^(-7) kg^(-1) d^(-1) keV^(-1). With an exposure of 5.6 ton-years, the sensitivity of Panda X-4 T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10^(-48) cm^2 at a dark matter mass of 40 Ge V/c^2.
基金This work was supported by a Double Top-class grant from Shanghai Jiao Tong University,and the National Natural Science Foundation of China(Grant No.11875190)Department of Energy(Grant No.de-sc0008541)the John Templeton Foundation(Grant No.#61884).
文摘Self-interacting dark matter(SIDM)is a leading candidate proposed to solve discrepancies between predictions of the prevailing cold dark matter theory and observations of galaxies.Many SIDM models predict the existence of a light force carrier that mediates strong dark matter self-interactions.If the mediator couples to the standard model particles,it could produce characteristic signals in dark matter direct detection experiments.We report searches for signals of SIDM models with a light mediator using the full dataset of the PandaX-II experiment,basing on a total exposure of 132 tonne-days.No significant excess over background is found,and our likelihood analysis leads to a strong upper limit on the dark matter-nucleon coupling strength.We further combine the PandaX-II constraints and those from observations of the light element abundances in the early universe,and show that direct detection and cosmological probes can provide complementary constraints on dark matter models with a light mediator.
基金Supported by a Double Top-class grant from Shanghai Jiao Tong University,grants from National Science Foundation of China(11435008,11525522,11775141,11755001)a grant from the Ministry of Science and Technology of China(2016YFA0400301)the Office of Science and Technology,Shanghai Municipal Government(11DZ2260700,16DZ2260200,18JC1410200)。
文摘We report the dark matter search results obtained using the full 132 ton·day exposure of the PandaX-II experiment,including all data from March 2016 to August 2018.No significant excess of events is identified above the expected background.Upper limits are set on the spin-independent dark matter-nucleon interactions.The lowest 90%confidence level exclusion on the spin-independent cross section is 2.2×10−46 cm2 at a WIMP mass of 30 GeV/c2.
基金This project is supported in part by grants from the Ministry of Science and Technology of China(No.2016YFA0400301 and 2016YFA0400302)grants from National Science Foundation of China(Nos.12090061,12090062,12005131,11905128,and 11925502)by Office of Science and Technology,Shanghai Municipal Government(grant No.18JC1410200).
文摘Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.
文摘Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei.As a future high energy nuclear physics project,an Electron-ion collider in China(EicC)has been proposed.It will be constructed based on an upgraded heavy-ion accelerator,High Intensity heavy-ion Accelerator Facility(HIAF)which is currently under construction,together with a new electron ring.The proposed collider will provide highly polarized electrons(with a po-larization of 80%)and protons(with a polarization of 70%)with variable center of mass energies from 15 to 20 GeV and the luminosity of(2–3)×1033 cm^(−2)·s^(−1).Polarized deuterons and Helium-3,as well as unpolarized ion beams from Carbon to Uranium,will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region,including 3D tomography of nucleon;the partonic structure of nuclei and the parton interaction with the nuclear environment;the exotic states,especially those with heavy flavor quark contents.In addition,issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC.In order to achieve the above-mentioned physics goals,a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe.The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States.The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.
基金supported by the Major State Basic Research Development Program in China(Grant Nos.2014CB845400,and 2015CB856904)the National Natural Science Foundation of China(Grant Nos.11775288,11421505,11628508,and 11520101004)
文摘We study the phase structure of QCD matter in the framework of a multiphase transport model by implementing a strong local parton density fluctuation scenario. Our calculations on the beam energy dependence of net-proton high moment show that local parton density fluctuation only has a small effect. But it becomes important when all baryons are included. We then study the effect on elliptic flow and find that an enhanced local parton density fluctuation leads to a significant effect on protons but a small effect on pions. Our study provides a reference of transport dynamics on QCD phase transition phenomena and will be relevant for the upcoming phase II of the beam energy scan program at RHIC.
基金Supported by grants from the Ministry of Science and Technology of China(2016YFA0400301,2016YFA0400302)a Double Top-class grant from Shanghai Jiao Tong University,grants from National Science Foundation of China(11435008,11505112,11525522,11775142,11755001)+3 种基金grants from the Office of Science and Technology,Shanghai Municipal Government(11DZ2260700,16DZ2260200,18JC1410200)the support from the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Educationsupported in part by the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)Hongwen Foundation in Hong Kong
文摘We report the Neutrino-less Double Beta Decay(NLDBD)search results from PandaX-II dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August 2018.With NLDBD-optimized event selection criteria,we obtain a fiducial mass of 219 kg of natural xenon.The accumulated xenon exposure is 242 kg·yr,or equivalently 22.2 kg·yr of 136Xe exposure.At the region around 136Xe decay Q-value of 2458 keV,the energy resolution of PandaX-II is 4.2%.We find no evidence of NLDBD in PandaX-II and establish a lower limit for decay half-life of 2.1 ×10^23 yr at the 90%confidence level,which corresponds to an effective Majorana neutrino mass mββ<(1.4-3.7) eV.This is the first NLDBD result reported from a dual-phase xenon experiment.
文摘Zpif’s law in the field of linguistics is tested in the nuclear disassembly within the framework of isospin dependent lattice gas model. It is found that the average cluster charge (or mass) of rank n in the charge (or mass) list shows exactly an inverse order to its rank, i.e., Zpif’s law appears at the phase transition temperature. This novel criterion shall be helpful in searching the nuclear liquid gas phase transition.
基金supported by the Double Top-class of Shanghai Jiao Tong University,the National Natural Science Foundation of China(Grant Nos.11435008,11505112,11525522,11775141,and 11755001)the Ministry of Science and Technology of China(Grant No.2016YFA0400301)+4 种基金the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,16DZ2260200,and 18JC1410200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education,for important supportthe Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)Hongwen Foundation in Hong Kongwe thank the CJPL administration and the Yalong River Hydropower Development Company Ltd.for indispensable logistical support and other help.
文摘In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.
基金Supported by a grant from the Ministry of Science and Technology of China(2016YFA0400301)National Science Foundation of China(12090060,11525522,11775141,11755001)Office of Science and Technology,Shanghai Municipal Government(18JC1410200)。
文摘We present a systematic determination of the responses of PandaX-Ⅱ,a dual phase xenon time projection chamber detector,to low energy recoils.The electron recoil(ER) and nuclear recoil(NR) responses are calibrated,respectively,with injected tritiated methane or 220Rn source,and with 241Am-Be neutron source,in an energy range from 1-25 keV(ER) and 4-80 keV(NR),under the two drift fields,400 and 317 V/cm.An empirical model is used to fit the light yield and charge yield for both types of recoils.The best fit models can describe the calibration data significantly.The systematic uncertainties of the fitted models are obtained via statistical comparison to the data.
基金Supported in part by a grant from the Ministry of Science and Technology of China(2016YFA0400301)National Science Foundation of China(12090060,12005131,11905128,11925502,11775141)Office of Science and Technology,Shanghai Municipal Government(18JC1410200)。
文摘Ⅰ.INTRODUCTION The direct detection of dark matter particles,especially the weakly interacting massive particles(WIMPs),is being actively carried out by a couple of experiments worldwide[1].In recent years,the PandaX-Ⅱ experiment located in the China Jinping Underground Laboratory(CJPL)[1-3],which uses the technology of dual phase liquid xenon time projection chambers(TPCs),has pushed the limits of the cross section between WIMPs and nucleons to a new level for most of the possible WIMP masses;other experiments of the same type are also being performed[4–10].
基金Supported in part by grants from National Science Foundation of China(12090061,12005131,11905128,11925502)the Ministry of Science and Technology of China(2016YFA0400301)the Office of Science and Technology,Shanghai Municipal Government(18JC1410200)。
文摘Neutron-induced nuclear recoil background is critical to dark matter searches in the PandaX-4T liquid xenon experiment.In this study,we investigate the features of neutron background in liquid xenon and evaluate its contribution in single scattering nuclear recoil events using three methods.The first method is fully based on Monte Carlo simulations.The last two are data-driven methods that also use multiple scattering signals and high energy signals in the data.In the PandaX-4T commissioning data with an exposure of 0.63 tonne-year,all these methods give a consistent result,i.e.,there are 1.15±0.57 neutron-induced backgrounds in the dark matter signal region within an approximated nuclear recoil energy window between 5 and 100 keV.