Bayesian analysis was employed to constrain the equation of state(EoS)of nuclear matter with a baryon density of up to six times the nuclear saturation density,using data from heavy-ion collisions at beam energies√S_...Bayesian analysis was employed to constrain the equation of state(EoS)of nuclear matter with a baryon density of up to six times the nuclear saturation density,using data from heavy-ion collisions at beam energies√S_(NN)=2-10GeV.The resulting EoS excellently agrees with that constrained by astrophysical observations.展开更多
We investigate the cold nuclear matter(CNM) effects on isolated prompt photon and isolated prompt photon associated jet productions in nuclear collisions at the NLO accuracy by using the EPS09 NLO nuclear parton distr...We investigate the cold nuclear matter(CNM) effects on isolated prompt photon and isolated prompt photon associated jet productions in nuclear collisions at the NLO accuracy by using the EPS09 NLO nuclear parton distribution functions and their error sets.Nuclear modification factors of isolated prompt photon and isolated prompt photon+jet productions due to CNM effects in p+A and A+A reactions at the RHIC and the LHC are provided with varying rapidity and transverse momentum of the final state photon.It is shown that the CNM effects on isolated prompt photon and photon+jet are modest,which give a small enhancement at low pT region and a more obvious suppression at large pT at central rapidity.At forward rapidity a pronounced suppression of γ as well as γ+jet is always observed.展开更多
In the paper,we discuss the development of the multigap resistive plate chamber time-of-fight(TOF)technology and the production of the solenoidal tracker at RHIC(STAR)TOF detector in China at the beginning of the twen...In the paper,we discuss the development of the multigap resistive plate chamber time-of-fight(TOF)technology and the production of the solenoidal tracker at RHIC(STAR)TOF detector in China at the beginning of the twenty-frst century.Subsequently,recent experimental results from the frst beam energy scan program(BES-I)at the Relativistic Heavy Ion Collider(RHIC)pertaining to measurements of collectivity,chirality,criticality,global polarization,strangeness,heavy favor,dilepton and light nuclei productions are reviewed.展开更多
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 cr...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 estimation.Based 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.展开更多
Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluc...Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluctuating strong force field with short correlation length.展开更多
We studied experimental background reconstruction methods for the measurement of the D-D correlation using PYTHIA simulation.The like-sign(LS)and side-band(SB)background methods,which are widely used in the experiment...We studied experimental background reconstruction methods for the measurement of the D-D correlation using PYTHIA simulation.The like-sign(LS)and side-band(SB)background methods,which are widely used in the experimental measurements of single D-meson production yields,were deployed for correlation study.It was found that the LS method,which describes the combinatorial background of single D^(0) meson yields,fails to reproduce the correlated background in the D^(0)-D^(0) correlation measurement,while the SB background method yields a good description of the background for both single D^(0) yields and the correlated background of the D^(0)-D^(0) correlation measurement.We further examined the validity of the correlation methods under different signal-to-background ratios,providing direct references for experimental measurements.展开更多
We report in this paper the alignment calibration of the STAR pixel detector(PXL) prototype for the RHIC2013 run and performance study of the full PXL detector installed and commissioned in the RHIC 2014 run. PXL dete...We report in this paper the alignment calibration of the STAR pixel detector(PXL) prototype for the RHIC2013 run and performance study of the full PXL detector installed and commissioned in the RHIC 2014 run. PXL detector is the innermost two silicon layers of the STAR heavy flavor tracker aiming at high-precision reconstruction of secondary decay vertex of heavy flavor particles. To achieve the physics goals, the calibration work was done on the detector with high precision. A histogram-based method was successfully applied for the alignment calibration, and the detector efficiency after alignment was studied using both p t p collision data and cosmic ray data.展开更多
In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The t...In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The two cathodes were placed symmetrically at two ends of the anode. The modifications were decrease the length of the cylindrical anode to 4 cm instead of 6 cm, transform the copper emission electrode shape from plate of 40 mm length, 25 mm width and 2 mm thickness to disc of 20 mm diameter and 2 mm thickness and transform the inner uncovered area of the emission electrode from slit of 30 mm length and 10 mm width to disc of 5 mm diameter. The copper emission electrode was placed in the middle of the cylindrical anode and has aperture in the center of different diameters. Faraday cup was placed at different distances from the emission electrode aperture. The electrical discharge and the output ion beam characteristics of the modified ion source were measured at different pressures using argon gas. It was found that the optimum operating conditions of the modified ion source are; anode-cathode distance equal to 6 mm, emission electrode aperture diameter equal to 2.5 mm and emission electrode aperture, Faraday cup distance equals 3 cm. The effect of axial samarium cobalt permanent magnet of intensity equal to 300 Gauss on the discharge characteristics of the ion source was determined.展开更多
Azimuthal anisotropy, especially for the multi-strange hadrons, is expected to be sensitive to the dynamical evolution in the early stage of high energy nuclear collisions. In this paper we present the latest results ...Azimuthal anisotropy, especially for the multi-strange hadrons, is expected to be sensitive to the dynamical evolution in the early stage of high energy nuclear collisions. In this paper we present the latest results of multi-strange hadron elliptic flow in Au ＋ Au collisions at √SNN=200GeV from the STAR experiment at RHIC. The number-of-quark scaling is evidenced with φ（ss） and Ω（sss） with highly statistical data, which shows strange quark collectivity at RHIC. The u2 of φ meson is found to be consistent with that of proton within statistical error bars at pw 〈 1 GeV/c.展开更多
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 ...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.展开更多
Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and u...Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and underlying event effect on jet radius R,colliding energy,color factor,transverse momentum are investigated by numerical simulations.Hadronization corrections give a negative contribution to the jet energy shift and its magnitude decreases with jet ET and colliding energy √s as well as jet radius R.However,the underlying event effect gives a positive contribution to the jet energy shift and its contribution increases with jet radius and √s.Hadronization and underlying event effect offset each other and could be canceled completely at a specific jet radius dubbed R_(NP)=0.It is observed that R_(NP)=0 decreases with colliding energy √s and is larger for a gluon jet than a quark jet at any fixed ET.展开更多
A variety of environmental media were analyzed for fallout radionuclides resulting from the Fukushima nuclear accident by the Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkel...A variety of environmental media were analyzed for fallout radionuclides resulting from the Fukushima nuclear accident by the Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. Monitoring activities in air and rainwater began soon after the onset of the March 11, 2011 tsunami and are reported here through the end of 2012. Observed fallout isotopes include 131I, 132I, 132Te, 134Cs, 136Cs, and 137Cs. Isotopes were measured on environmental air filters, automobile filters, and in rainwater. An additional analysis of rainwater in search of 90Sr is also presented. Last, a series of food measurements conducted in September of 2013 are included due to extended media concerns of 134,137Cs in fish. Similar measurements of fallout from the Chernobyl disaster at LBNL, previously unpublished publicly, are also presented here as a comparison with the Fukushima incident. All measurements presented also include natural radionuclides found in the environment to provide a basis for comparison.展开更多
The ART model is applied to study the deformed UU collision at HIRFL-CSR energy area corresponding to the high baryon density region in the QCD phase diagram. The time evolution of central baryon （energy） densities ...The ART model is applied to study the deformed UU collision at HIRFL-CSR energy area corresponding to the high baryon density region in the QCD phase diagram. The time evolution of central baryon （energy） densities in central collisions at Eb = 0.52 GeV/u shows that different orientation collisions will lead to different lifetimes of high density, especially tip-tip UU collisions which have an extend lifetime for the high density phase by almost a factor of 2 compared to the body-body orientation collisions. In order to pick out the interesting tip-tip like events from a mass of random orientation collisions, we study the relation between stopping power R and impact parameter b in different orientation collisions and find that it can enhance the purity of tip-tip like events when R increases. Therefore, the high density and long lifetime events can be effectively distinguished by R selection.展开更多
Decay constants of pseudoscalar mesons D,D_(s),η_(c) and vector mesons D^(*),D_(s)^(*),J/ψ are determined from the N_(f)=2+1 lattice QCD at a lattice spacing a~0.08 fm.For vector mesons,the decay constants defined b...Decay constants of pseudoscalar mesons D,D_(s),η_(c) and vector mesons D^(*),D_(s)^(*),J/ψ are determined from the N_(f)=2+1 lattice QCD at a lattice spacing a~0.08 fm.For vector mesons,the decay constants defined by tensor currents are given in the MS scheme at 2 GeV.The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD collaborations and the overlap fermion action is used for the valence quarks.Comparing the current results with our previous results at a coarser lattice spacing a ~0.11 fm provides a better understanding of the discretization error.We obtain f_(D_(s)^(*))^(T)(MS,2 GeV)/f_(D_(s)^(*))=0.909(18)with a better precision than our previous result.Combining our f_(D_(s)^(*))=277(11)MeV with the total width of D_(s)^(*) determined in a recent study gives a branching fraction 4.26(52)×10^(-5) for D_(s)^(*) leptonic decay.展开更多
文摘Bayesian analysis was employed to constrain the equation of state(EoS)of nuclear matter with a baryon density of up to six times the nuclear saturation density,using data from heavy-ion collisions at beam energies√S_(NN)=2-10GeV.The resulting EoS excellently agrees with that constrained by astrophysical observations.
基金Supported by the Ministry of Education of China with Project No. NCET-09-0411the National Natural Science Foundation of China with Project Nos. 11075062,11221504+1 种基金the Natural Science Foundation of Hubei Province with Project No. 2010CDA075Self-Determined Research Funds of CCNU
文摘We investigate the cold nuclear matter(CNM) effects on isolated prompt photon and isolated prompt photon associated jet productions in nuclear collisions at the NLO accuracy by using the EPS09 NLO nuclear parton distribution functions and their error sets.Nuclear modification factors of isolated prompt photon and isolated prompt photon+jet productions due to CNM effects in p+A and A+A reactions at the RHIC and the LHC are provided with varying rapidity and transverse momentum of the final state photon.It is shown that the CNM effects on isolated prompt photon and photon+jet are modest,which give a small enhancement at low pT region and a more obvious suppression at large pT at central rapidity.At forward rapidity a pronounced suppression of γ as well as γ+jet is always observed.
基金National Key Research and Development Program of China(No.2022YFA1604900)National Natural Science Foundation of China(No.12025501)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34000000)。
文摘In the paper,we discuss the development of the multigap resistive plate chamber time-of-fight(TOF)technology and the production of the solenoidal tracker at RHIC(STAR)TOF detector in China at the beginning of the twenty-frst century.Subsequently,recent experimental results from the frst beam energy scan program(BES-I)at the Relativistic Heavy Ion Collider(RHIC)pertaining to measurements of collectivity,chirality,criticality,global polarization,strangeness,heavy favor,dilepton and light nuclei productions are reviewed.
基金supported in part by the Mo ST of China 973-Project(No.2015CB856901)the National Natural Science Foundation of China(No.11575069)
文摘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 estimation.Based 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.
文摘Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluctuating strong force field with short correlation length.
基金supported in part by the National Natural Science Foundation of China(Nos.11890710,11890714,11905034)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB34000000)。
文摘We studied experimental background reconstruction methods for the measurement of the D-D correlation using PYTHIA simulation.The like-sign(LS)and side-band(SB)background methods,which are widely used in the experimental measurements of single D-meson production yields,were deployed for correlation study.It was found that the LS method,which describes the combinatorial background of single D^(0) meson yields,fails to reproduce the correlated background in the D^(0)-D^(0) correlation measurement,while the SB background method yields a good description of the background for both single D^(0) yields and the correlated background of the D^(0)-D^(0) correlation measurement.We further examined the validity of the correlation methods under different signal-to-background ratios,providing direct references for experimental measurements.
基金supported in part by the National Natural Science Foundation of China(No.11421505)the Major State Basic Research Development Program in China(No.2014CB845400)
文摘We report in this paper the alignment calibration of the STAR pixel detector(PXL) prototype for the RHIC2013 run and performance study of the full PXL detector installed and commissioned in the RHIC 2014 run. PXL detector is the innermost two silicon layers of the STAR heavy flavor tracker aiming at high-precision reconstruction of secondary decay vertex of heavy flavor particles. To achieve the physics goals, the calibration work was done on the detector with high precision. A histogram-based method was successfully applied for the alignment calibration, and the detector efficiency after alignment was studied using both p t p collision data and cosmic ray data.
文摘In this paper, design and construction of a modified cold molybdenum cathode Penning ion source was described. It consists of copper cylindrical anode with two cone ends and two movable cold molybdenum cathodes. The two cathodes were placed symmetrically at two ends of the anode. The modifications were decrease the length of the cylindrical anode to 4 cm instead of 6 cm, transform the copper emission electrode shape from plate of 40 mm length, 25 mm width and 2 mm thickness to disc of 20 mm diameter and 2 mm thickness and transform the inner uncovered area of the emission electrode from slit of 30 mm length and 10 mm width to disc of 5 mm diameter. The copper emission electrode was placed in the middle of the cylindrical anode and has aperture in the center of different diameters. Faraday cup was placed at different distances from the emission electrode aperture. The electrical discharge and the output ion beam characteristics of the modified ion source were measured at different pressures using argon gas. It was found that the optimum operating conditions of the modified ion source are; anode-cathode distance equal to 6 mm, emission electrode aperture diameter equal to 2.5 mm and emission electrode aperture, Faraday cup distance equals 3 cm. The effect of axial samarium cobalt permanent magnet of intensity equal to 300 Gauss on the discharge characteristics of the ion source was determined.
基金supported by National Natural Science Foundation of China (No. 10905029)by China Postdoctoral Science Foundation(No. 20100480017)by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098
文摘Azimuthal anisotropy, especially for the multi-strange hadrons, is expected to be sensitive to the dynamical evolution in the early stage of high energy nuclear collisions. In this paper we present the latest results of multi-strange hadron elliptic flow in Au ＋ Au collisions at √SNN=200GeV from the STAR experiment at RHIC. The number-of-quark scaling is evidenced with φ（ss） and Ω（sss） with highly statistical data, which shows strange quark collectivity at RHIC. The u2 of φ meson is found to be consistent with that of proton within statistical error bars at pw 〈 1 GeV/c.
基金Supported by the National Natural Science Foundation of China under Grant No.19875012the Scientific Research Foundation of Harbin Institute of Technology.
文摘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.
基金the New Century Excellent Talent Project(NCET)of the Ministry of Education of China under Grant No NCET-09-0411the National Natural Science Foundation of Chinathe Self-Determined Fund of WUST and CCNU.
文摘Utilizing PYTHIA we study non-pertubative QCD effects to jet transverse momentum shift in hadronic collisions at the RHIC and the LHC.The dependences of non-perturbative effects such as hadronization corrections and underlying event effect on jet radius R,colliding energy,color factor,transverse momentum are investigated by numerical simulations.Hadronization corrections give a negative contribution to the jet energy shift and its magnitude decreases with jet ET and colliding energy √s as well as jet radius R.However,the underlying event effect gives a positive contribution to the jet energy shift and its contribution increases with jet radius and √s.Hadronization and underlying event effect offset each other and could be canceled completely at a specific jet radius dubbed R_(NP)=0.It is observed that R_(NP)=0 decreases with colliding energy √s and is larger for a gluon jet than a quark jet at any fixed ET.
基金supported by the Department of Energy National Nuclear Security Administration under Award Number(s)DE-NA0000979by the Director,Office of Energy Research,Office of High Energy and Nuclear Physics,Division of Nuclear Physics,of the US Department of Energy under Contract No.DE-AC02-05CH11231.
文摘A variety of environmental media were analyzed for fallout radionuclides resulting from the Fukushima nuclear accident by the Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. Monitoring activities in air and rainwater began soon after the onset of the March 11, 2011 tsunami and are reported here through the end of 2012. Observed fallout isotopes include 131I, 132I, 132Te, 134Cs, 136Cs, and 137Cs. Isotopes were measured on environmental air filters, automobile filters, and in rainwater. An additional analysis of rainwater in search of 90Sr is also presented. Last, a series of food measurements conducted in September of 2013 are included due to extended media concerns of 134,137Cs in fish. Similar measurements of fallout from the Chernobyl disaster at LBNL, previously unpublished publicly, are also presented here as a comparison with the Fukushima incident. All measurements presented also include natural radionuclides found in the environment to provide a basis for comparison.
基金Supported by the National Natural Science Foundation of China under Grant No 10775058, the Ministry of Education of China under Grant No IRT0624, the U.S. Department of Energy under Contract No DE-AC03-76SF00098, and Chinese Academy of Sciences under Grant Nos KJCX2-SW-N18 and CXTD-J2005-1.
文摘The ART model is applied to study the deformed UU collision at HIRFL-CSR energy area corresponding to the high baryon density region in the QCD phase diagram. The time evolution of central baryon （energy） densities in central collisions at Eb = 0.52 GeV/u shows that different orientation collisions will lead to different lifetimes of high density, especially tip-tip UU collisions which have an extend lifetime for the high density phase by almost a factor of 2 compared to the body-body orientation collisions. In order to pick out the interesting tip-tip like events from a mass of random orientation collisions, we study the relation between stopping power R and impact parameter b in different orientation collisions and find that it can enhance the purity of tip-tip like events when R increases. Therefore, the high density and long lifetime events can be effectively distinguished by R selection.
基金Supported in part by the National Key Research and Development Program of China(2020YFA0406400,2023YFA1606002)the National Natural Science Foundation of China(12075253,11935017,12192264,12293060,12293065,12293063,12070131001)+1 种基金CRC 110 by DFG and NNSFCsupported by the U.S.DOE Grant(DE-SC0013065)and DOE Grant(DEAC05-06OR23177),which is within the framework of the TMD Topical Collaboration。
文摘Decay constants of pseudoscalar mesons D,D_(s),η_(c) and vector mesons D^(*),D_(s)^(*),J/ψ are determined from the N_(f)=2+1 lattice QCD at a lattice spacing a~0.08 fm.For vector mesons,the decay constants defined by tensor currents are given in the MS scheme at 2 GeV.The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD collaborations and the overlap fermion action is used for the valence quarks.Comparing the current results with our previous results at a coarser lattice spacing a ~0.11 fm provides a better understanding of the discretization error.We obtain f_(D_(s)^(*))^(T)(MS,2 GeV)/f_(D_(s)^(*))=0.909(18)with a better precision than our previous result.Combining our f_(D_(s)^(*))=277(11)MeV with the total width of D_(s)^(*) determined in a recent study gives a branching fraction 4.26(52)×10^(-5) for D_(s)^(*) leptonic decay.
