The production of π^(0),η,andφin the most central(0%-5%)Xe+Xe collisions at √s_(NN)=5.44 TeV is investigated in the framework of the perturbative QCD(pQCD)improved parton model at an accuracy of next-toleading ord...The production of π^(0),η,andφin the most central(0%-5%)Xe+Xe collisions at √s_(NN)=5.44 TeV is investigated in the framework of the perturbative QCD(pQCD)improved parton model at an accuracy of next-toleading order(NLO).The jet quenching effect is effectively incorporated by medium-modified fragmentation functions via the higher-twist approach.Predictions of the nuclear modification factors of π^(0),η,and φ as functions of the transverse momentum p_(T) are made with the jet transport parameter q_(0),which is extracted from the available experimental data of charged hadrons provided by ALICE and CMS.The particle ratios η/π^(0),φ/π^(0) as functions of p_(T) in Xe+Xe collisions at √s_(NN)=5.44 TeV as well as in 0%-5% Pb+Pb collisions at √s_(NN)=5.02 TeV are also presented.The numerical simulations of the scaled ratios of charged hadron production in the Xe+Xe 5.44 TeV system over those in the Pb+Pb 5.02 TeV system give a good description of the CMS data,and the scaled ratios of π^(0),η,and φ production coincide with the curve of charged hadron production.展开更多
An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented. This paper includes four parts： 1） Theoretical predictions of quarkgluon p...An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented. This paper includes four parts： 1） Theoretical predictions of quarkgluon plasma and introduction for high energy heavy ion collision experiments. 2） Experimental status on collision geometry. 3） Experimental status on particle production. 4） Conclusion and outlook for research status of soft physics in LHC/ALICE.展开更多
Production of light complex particles from the n＋^238u reaction is analyzed with the exciton model including the improved Iwamoto-Harada pickup mechanism for the preequilibrium process. It is allowed that some of the...Production of light complex particles from the n＋^238u reaction is analyzed with the exciton model including the improved Iwamoto-Harada pickup mechanism for the preequilibrium process. It is allowed that some of the nucleons forming the complex ejectile come from levels below the Fermi energy, and the intrinsic structure of the emitted particle is taken into account. The equilibrium-state emissions are also considered by using Hauser- Feshbach theory with the width fluctuation correction and the evaporation model angular distributions, energy spectra and double differential cross sections of neutron, alpha emissions for the n＋^238U reaction are consistently calculated and analyzed with the energy range En ≤150 MeV. ENDF-formatted nuclear data including information charged particles are obtained. Moreover, all cross sections, proton, deuteron, triton and nuclear theoretical models in about the production of light展开更多
[Objective] The aim was to discuss he produce and elimination rules of particles in Beijing during early 2008 Olympic Games. [Method] Based on the analysis of particulate matter online observation data and meteorologi...[Objective] The aim was to discuss he produce and elimination rules of particles in Beijing during early 2008 Olympic Games. [Method] Based on the analysis of particulate matter online observation data and meteorological data during the corresponding period in Chinese environmental science college, Hysplit Back trace model and Numerical weather prediction graphs, and combined with the different analytical methods on meteorological flow fields, a typical process of particles in Beijing during early 2008 Olympic Games was studied. [Result] The results indicated that during the ascent stage of PM2.5 concentration, the PM showed gradually aging phenomena; the process controlled by large scale synoptic system mainly. And the weak wind and the high humidity were not in favor of dispersion; the prolonged southerly air mass to bring the pollutant of Hebei, Taijin and Shandong to Beijing; mixing height and temperature curve took the importance role to the pollution. [Conclusion] The study provided theoretical basis for the discussion on factors influencing the production and elimination of particles in the air pollution process.展开更多
Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential a...Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.展开更多
Massless quark pair production in SU(2) gauge chromoelectric field is investigated by solving the Wigner function with back reaction. The temporal evolution of specific field and its current are obtained self consiste...Massless quark pair production in SU(2) gauge chromoelectric field is investigated by solving the Wigner function with back reaction. The temporal evolution of specific field and its current are obtained self consistently. For the quark distribution function, both its time and momentum dependence are studied. In particular, some interesting phenomena are found, for example, the more abundant symmetry or/and antisymmetry characteristics, the existence of the attractive basin structure and the existence of the momentum "gap" in the quark distribution and so on. All the phenomena are associated with the quark-gluon plasma oscillation, which due to the back reaction effect. The study and analysis qualitatively about the components of the Wigner function are expected to be helpful to deepen the understanding of the QCD vacuum.展开更多
Suspended asphaltenic heavy organic particles in petroleum fluids may stick to the inner walls of oil wells and pipelines. This is the major reason for fouling and arterial blockage in the petroleum industry. This rep...Suspended asphaltenic heavy organic particles in petroleum fluids may stick to the inner walls of oil wells and pipelines. This is the major reason for fouling and arterial blockage in the petroleum industry. This report is devoted the study of the mechanism of migration of suspended heavy organic particles towards the walls in oil-producing wells and pipelines. In this report we present a detailed analytical model for the heavy organics suspended particle deposition coefficient corresponding to petroleum fluids flow production conditions in oil wells. We predict the rate of particle deposition during various turbulent flow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of flowing conduits. The developed model accounts for the eddy diffusivity, and Brownian diffusivity as well as for inertial effects. The analysis presented in this paper shows that rates of particle deposition （during petroleum fluid production） on the walls of the flowing channel due solely to diffusion effects are small. It is also shown that deposition rates decrease with increasing particle size. However, when the process is momentum controlled （large particle sizes） higher deposition rates are expected.展开更多
Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performan...Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.展开更多
In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flo- tation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this stud...In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flo- tation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this study, bubble distributions in different reagent concentrations, electrolyte concentrations, cathode apertures, and current densities in electroflotation are determined using a high-speed camera. Average bubble sizes under different conditions are calculated using Image-Pro@ Plus （Media Cybernetics@, MD, USA） and SigmaScan@ Pro （Systat Software, CA, USA） software. Results indicate that the average sizes of bubbles, which were generated through 38, 50, 74, 150, 250, 420, and 1000 μm cathode apertures, are 20.2, 29.5, 44.6, 59.2, 68.7, 78.5, and 88.8 μm, respectively. The optimal current density in electroflotation is 20 A/m2. Reagent and electrolyte concentrations, current density, and cathode aperture are important factors in controlling bubble size and nucleation. These factors also contribute to the control of fine- Particle flotation.展开更多
Solar flare gamma-ray emissions from energetic ions and electrons have been detected and measured to GeV energies since 1980. In addition, neutrons produced in solar flares with 100 MeV to GeV energies have been obser...Solar flare gamma-ray emissions from energetic ions and electrons have been detected and measured to GeV energies since 1980. In addition, neutrons produced in solar flares with 100 MeV to GeV energies have been observed at the Earth. These emissions are produced by the highest energy ions and electrons accelerated at the Sun and they provide our only direct （albeit secondary） knowledge about the properties of the accelerator（s） acting in a solar flare. The solar flares, which have direct evidence for pion-decay gamma-rays, are unique and are the focus of this paper. We review our current knowledge of the highest energy solar emissions, and how the characteristics of the acceleration process are deduced from the observations. Results from the RHESSI, INTEGRAL and CORONAS missions will also be covered. The review will also cover the solar flare capabilities of the new mission, FERMI GAMMA RAY SPACE TELESCOPE, launched on 2008 June II. Finally, we discuss the requirements for future missions to advance this vital area of solar flare physics.展开更多
Formation of new atmospheric aerosol particles is a global phenomenon that has been observed to take place in even heavily-polluted environments. However, in all environments there appears to be a threshold value of t...Formation of new atmospheric aerosol particles is a global phenomenon that has been observed to take place in even heavily-polluted environments. However, in all environments there appears to be a threshold value of the condensation sink （due to pre-existing aerosol particles） after which the formation rate of 3 nm particles is no longer detected. In China new particle production has been observed at very high pollution levels （condensation sink about 0.1 s-1 ） m several megaclt es, including Beijing, Shanghai and Nanjing as well as in Pearl River Delta （PRD）. Here we summarize the recent findings obtained from these studies and discuss the various implications these findings will have on future research and policy.展开更多
Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum ...Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum of J/ψ pairs is studied.A narrow structure around 6:9 GeV=c^2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed.The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV=c^2,covering predicted masses of states composed of four charm quarks.The mass and natural width of the narrow X(6900)structure are measured assuming a Breit-Wigner lineshape.展开更多
First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b^(-)J/ψΛK^(-)decays.The observed structure is consistent with being due to a charmonium pentaquark w...First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b^(-)J/ψΛK^(-)decays.The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1r including systematic uncertainties and lookelsewhere effect.Its mass and width are determined to be 4458:8±2:9t4:7-1:1 MeV and 17:3±6:5t8:0-5:7 MeV,respectively,where the quoted uncertainties are statistical and systematic.The structure is also consistent with being due to two resonances.In addition,the narrow excited■^(-)states,N■(1690)and■(1820),are seen for the first time in a■b^(-)decay,and their masses and widths are measured with improved precision.The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb^(-1),collected with the LHCb experiment at centre-of-mass energies of 7,8 and 13 TeV.展开更多
A search for the doubly charmed baryon ■^+cc is performed through its decay to theΛ^+c K^-π^+ final state,using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7,8 and 13...A search for the doubly charmed baryon ■^+cc is performed through its decay to theΛ^+c K^-π^+ final state,using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7,8 and 13 TeV.The data correspond to a total integrated luminosity of 9 fb^-1.No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c^2.Upper limits are set at 95%credibility level on the ratio of the ■^+cc production cross-section times the branching fraction to that ofΛ^+c and ■^++cc baryons.The limits are determined as functions of the ■^+cc mass for different lifetime hypotheses,in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.展开更多
A search for the doubly charmed baryon ?cc+ with the decay mode c Ω_(cc)^(+)→ Ξc+K-π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016...A search for the doubly charmed baryon ?cc+ with the decay mode c Ω_(cc)^(+)→ Ξc+K-π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb-1. No significant signal is observed within the invariant mass range of 3.6 to 4.0 GeV/c2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω_(cc)^(+)→ Ξc+K-π+ decay with respect to the Ξcc++→ Λc+K-π+π+ decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for diferent hypotheses on the ?cc+ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.展开更多
基金Supported by the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030008)the Natural Science Foundation of China with Project(11935007,11805167)。
文摘The production of π^(0),η,andφin the most central(0%-5%)Xe+Xe collisions at √s_(NN)=5.44 TeV is investigated in the framework of the perturbative QCD(pQCD)improved parton model at an accuracy of next-toleading order(NLO).The jet quenching effect is effectively incorporated by medium-modified fragmentation functions via the higher-twist approach.Predictions of the nuclear modification factors of π^(0),η,and φ as functions of the transverse momentum p_(T) are made with the jet transport parameter q_(0),which is extracted from the available experimental data of charged hadrons provided by ALICE and CMS.The particle ratios η/π^(0),φ/π^(0) as functions of p_(T) in Xe+Xe collisions at √s_(NN)=5.44 TeV as well as in 0%-5% Pb+Pb collisions at √s_(NN)=5.02 TeV are also presented.The numerical simulations of the scaled ratios of charged hadron production in the Xe+Xe 5.44 TeV system over those in the Pb+Pb 5.02 TeV system give a good description of the CMS data,and the scaled ratios of π^(0),η,and φ production coincide with the curve of charged hadron production.
基金Ministry of Education of China(306022)National Natural Science Foundation of China(10635020)
文摘An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented. This paper includes four parts： 1） Theoretical predictions of quarkgluon plasma and introduction for high energy heavy ion collision experiments. 2） Experimental status on collision geometry. 3） Experimental status on particle production. 4） Conclusion and outlook for research status of soft physics in LHC/ALICE.
基金Supported by National Natural Science Foundation of China-NSAF(U1630122)IAEA Coordinated Research Projects(CRPs)on Recommended Input Parameter Library(RIPL)for Fission Cross Section Calculations(20464)Science Challenge Project(TZ2018005)
文摘Production of light complex particles from the n＋^238u reaction is analyzed with the exciton model including the improved Iwamoto-Harada pickup mechanism for the preequilibrium process. It is allowed that some of the nucleons forming the complex ejectile come from levels below the Fermi energy, and the intrinsic structure of the emitted particle is taken into account. The equilibrium-state emissions are also considered by using Hauser- Feshbach theory with the width fluctuation correction and the evaporation model angular distributions, energy spectra and double differential cross sections of neutron, alpha emissions for the n＋^238U reaction are consistently calculated and analyzed with the energy range En ≤150 MeV. ENDF-formatted nuclear data including information charged particles are obtained. Moreover, all cross sections, proton, deuteron, triton and nuclear theoretical models in about the production of light
基金Supported by Central Public Welfare Research Institutes of BasicResearch Operations Special Fund (2008KYYW01)
文摘[Objective] The aim was to discuss he produce and elimination rules of particles in Beijing during early 2008 Olympic Games. [Method] Based on the analysis of particulate matter online observation data and meteorological data during the corresponding period in Chinese environmental science college, Hysplit Back trace model and Numerical weather prediction graphs, and combined with the different analytical methods on meteorological flow fields, a typical process of particles in Beijing during early 2008 Olympic Games was studied. [Result] The results indicated that during the ascent stage of PM2.5 concentration, the PM showed gradually aging phenomena; the process controlled by large scale synoptic system mainly. And the weak wind and the high humidity were not in favor of dispersion; the prolonged southerly air mass to bring the pollutant of Hebei, Taijin and Shandong to Beijing; mixing height and temperature curve took the importance role to the pollution. [Conclusion] The study provided theoretical basis for the discussion on factors influencing the production and elimination of particles in the air pollution process.
基金funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)funding from LASERLAB-EUROPE(Grant Agreement No.871124,European Union’s Horizon 2020 Research and Innovation Program)+5 种基金supported in part by the United States Department of Energy under Grant No.DE-FG02-93ER40773We also acknowledge support from Grant No.PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Union and Unidad de Investigación Consolidada of Junta de Castilla y León UIC 167supported in part by the National Natural Science Foundation of China under Grant No.12375125the Fundamental Research Funds for the Central Universitiesthe support of the Czech Science Foundation through Grant No.GACR24-11398S.
文摘Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.
基金Supported by the National Natural Science Foundation of China under Grant No.11475026
文摘Massless quark pair production in SU(2) gauge chromoelectric field is investigated by solving the Wigner function with back reaction. The temporal evolution of specific field and its current are obtained self consistently. For the quark distribution function, both its time and momentum dependence are studied. In particular, some interesting phenomena are found, for example, the more abundant symmetry or/and antisymmetry characteristics, the existence of the attractive basin structure and the existence of the momentum "gap" in the quark distribution and so on. All the phenomena are associated with the quark-gluon plasma oscillation, which due to the back reaction effect. The study and analysis qualitatively about the components of the Wigner function are expected to be helpful to deepen the understanding of the QCD vacuum.
文摘Suspended asphaltenic heavy organic particles in petroleum fluids may stick to the inner walls of oil wells and pipelines. This is the major reason for fouling and arterial blockage in the petroleum industry. This report is devoted the study of the mechanism of migration of suspended heavy organic particles towards the walls in oil-producing wells and pipelines. In this report we present a detailed analytical model for the heavy organics suspended particle deposition coefficient corresponding to petroleum fluids flow production conditions in oil wells. We predict the rate of particle deposition during various turbulent flow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of flowing conduits. The developed model accounts for the eddy diffusivity, and Brownian diffusivity as well as for inertial effects. The analysis presented in this paper shows that rates of particle deposition （during petroleum fluid production） on the walls of the flowing channel due solely to diffusion effects are small. It is also shown that deposition rates decrease with increasing particle size. However, when the process is momentum controlled （large particle sizes） higher deposition rates are expected.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675484,51275474,51505424)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LZ12E05002,LY15E050019)
文摘Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.
基金the National Natural Science Foundation of China (No.50774094)the Ministry of Science and Technology of China (No.2011BAB05B01) for financial support
文摘In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flo- tation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this study, bubble distributions in different reagent concentrations, electrolyte concentrations, cathode apertures, and current densities in electroflotation are determined using a high-speed camera. Average bubble sizes under different conditions are calculated using Image-Pro@ Plus （Media Cybernetics@, MD, USA） and SigmaScan@ Pro （Systat Software, CA, USA） software. Results indicate that the average sizes of bubbles, which were generated through 38, 50, 74, 150, 250, 420, and 1000 μm cathode apertures, are 20.2, 29.5, 44.6, 59.2, 68.7, 78.5, and 88.8 μm, respectively. The optimal current density in electroflotation is 20 A/m2. Reagent and electrolyte concentrations, current density, and cathode aperture are important factors in controlling bubble size and nucleation. These factors also contribute to the control of fine- Particle flotation.
文摘Solar flare gamma-ray emissions from energetic ions and electrons have been detected and measured to GeV energies since 1980. In addition, neutrons produced in solar flares with 100 MeV to GeV energies have been observed at the Earth. These emissions are produced by the highest energy ions and electrons accelerated at the Sun and they provide our only direct （albeit secondary） knowledge about the properties of the accelerator（s） acting in a solar flare. The solar flares, which have direct evidence for pion-decay gamma-rays, are unique and are the focus of this paper. We review our current knowledge of the highest energy solar emissions, and how the characteristics of the acceleration process are deduced from the observations. Results from the RHESSI, INTEGRAL and CORONAS missions will also be covered. The review will also cover the solar flare capabilities of the new mission, FERMI GAMMA RAY SPACE TELESCOPE, launched on 2008 June II. Finally, we discuss the requirements for future missions to advance this vital area of solar flare physics.
基金The work in this manuscript is supported by Academy of Finland via Center of Excellence in Atmospheric Sciences （Project No. 272041） and the Finnish Funding Agency for Technology and Innovation TEKES via Beautiful Beijing project （No. 3667/31/2013） and European Research Council Advanced Grant （ATMNUCLE, 227463） and InGOS DEFROST and CRAICC （No. 26060） and Nordforsk CRAICC-PEEX （amendment to contact 26060） funded by Nordforsk. The SORPES station was supported by Nanjing University and the Collaborative Innovation Center of Climate Change in Jiangsu Province, China. Part of Aijun Ding＇s work was supported by the excellent young scientist fund of National Natural Science Foundation of China （No. D0512/41422504）.
文摘Formation of new atmospheric aerosol particles is a global phenomenon that has been observed to take place in even heavily-polluted environments. However, in all environments there appears to be a threshold value of the condensation sink （due to pre-existing aerosol particles） after which the formation rate of 3 nm particles is no longer detected. In China new particle production has been observed at very high pollution levels （condensation sink about 0.1 s-1 ） m several megaclt es, including Beijing, Shanghai and Nanjing as well as in Pearl River Delta （PRD）. Here we summarize the recent findings obtained from these studies and discuss the various implications these findings will have on future research and policy.
基金support from CERNfrom the national agencies: CAPES, CNPq, FAPERJ and FINEP (Brazil)+20 种基金MOST and NSFC (China)CNRS/IN2P3 (France)BMBF, DFG and MPG (Germany)INFN (Italy)NWO (Netherlands)MNiSW and NCN (Poland)MEN/IFA (Romania)MSHE (Russia)MinECo (Spain)SNSF and SER (Switzerland)NASU (Ukraine)STFC (United Kingdom)DOE NP and NSF (USA)AvH Foundation (Germany)EPLANET, Marie Sklodowska-Curie Actions and ERC (European Union)A^(*)MIDEX, ANR, Labex P2IO and OCEVU, and Region Auvergne-Rhone-Alpes (France)Key Research Program of Frontier Sciences of CAS, CAS PIFIthe Thousand Talents Program (China)RFBR, RSF and Yandex LLC (Russia)GVA, XuntaGal and GENCAT (Spain)the Royal Society and the Leverhulme Trust (United Kingdom)。
文摘Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum of J/ψ pairs is studied.A narrow structure around 6:9 GeV=c^2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed.The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV=c^2,covering predicted masses of states composed of four charm quarks.The mass and natural width of the narrow X(6900)structure are measured assuming a Breit-Wigner lineshape.
文摘First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b^(-)J/ψΛK^(-)decays.The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1r including systematic uncertainties and lookelsewhere effect.Its mass and width are determined to be 4458:8±2:9t4:7-1:1 MeV and 17:3±6:5t8:0-5:7 MeV,respectively,where the quoted uncertainties are statistical and systematic.The structure is also consistent with being due to two resonances.In addition,the narrow excited■^(-)states,N■(1690)and■(1820),are seen for the first time in a■b^(-)decay,and their masses and widths are measured with improved precision.The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb^(-1),collected with the LHCb experiment at centre-of-mass energies of 7,8 and 13 TeV.
基金support from CERN and from the national agencies:CAPES,CNPq，FAPERJ and FINEP(Brazil)MOST and NSFC(China)+11 种基金CNRS/IN2P3(France)BMBF,DFG and MPG(Germany)INFN(Italy)KWO(Netherlands)MNiSW and NCN(Poland)MEN/IFA(Romania)MinES and FASO(Russia)MinECo(Spain)SNSF and SER(Switzerland)NASU(Ukraine)STFC(United Kingdom)NSF(USA).
文摘A search for the doubly charmed baryon ■^+cc is performed through its decay to theΛ^+c K^-π^+ final state,using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7,8 and 13 TeV.The data correspond to a total integrated luminosity of 9 fb^-1.No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c^2.Upper limits are set at 95%credibility level on the ratio of the ■^+cc production cross-section times the branching fraction to that ofΛ^+c and ■^++cc baryons.The limits are determined as functions of the ■^+cc mass for different lifetime hypotheses,in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.
基金Open Access funding provided by CERN(European Organization for Nuclear Research).
文摘A search for the doubly charmed baryon ?cc+ with the decay mode c Ω_(cc)^(+)→ Ξc+K-π+ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb-1. No significant signal is observed within the invariant mass range of 3.6 to 4.0 GeV/c2. Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω_(cc)^(+)→ Ξc+K-π+ decay with respect to the Ξcc++→ Λc+K-π+π+ decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for diferent hypotheses on the ?cc+ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.
