Observation of Au + Au → Au + Au + ρ 0 and Au + Au → Au* + Au* + ρ 0 with STAR

We report the first observation of the reactions Au + Au → Au + Au + ρ ⁰ and Au + Au → Au* + Au* + ρ ⁰ with the STAR detector. The ρ are produced at small perpendicular momentum, as expected if they couple coherently to both nuclei. We discuss models of vector meson production and the correlation with nuclear breakup, and present a fundamental test of quantum mechanics that is possible with the system.     

Rapidity equilibration in d + Au and Au + Au systems

In a Relativistic Diffusion Model (RDM), the evolution of net-proton rapidity spectra with in heavy systems is proposed as an indicator for local equilibration and longitudinal expansion. The broad midrapidity valley recently discovered at RHIC in central Au + Au collisions at = 200 GeV suggests rapid local equilibration which is most likely due to deconfinement, and fast longitudinal expansion. Rapidity spectra of produced charged hadrons in d + Au and Au + Au systems at RHIC energies and their centrality dependence are well described in a three-sources RDM. In central collisions, about 19% of the produced particles are in the equilibrated midrapidity region for d + Au.     

Quarkonium production from d + Au to Au + Au collisions

The PHENIX experiment measured J/ production in pp, d + Au and Au + Au reactions at = 200 GeV over a wide range of rapidity and transverse momentum. The nuclear modification factor obtained by comparing the d + Au and pp cross sections as a function of rapidity, is consistent with shadowing of the gluon distribution functions. J/ production in Au + Au collisions was compared to the production in pp collisions and it was found to be inconsistent with models that predict strong enhancement relative to binary collision scaling. Arrival of the final proofs: 29 June 2005 PACS: 25.75-q, 25.75-Dw, ^* Deceased Spokesperson     

Time evolution of relativistic d + Au and Au + Au collisions

The evolution of charged‐particle production in collisions of heavy ions at relativistic energies is investigated as function of centrality in a nonequilibrium‐statistical framework. Precise agreement with recent d + Au and Au + Au data at = 200 GeV is found in a Relativistic Diffusion Model with three sources for particle production. Only the midrapidity source comes very close to local equilibrium, whereas the analyses of the overall pseudorapidity distributions show that the systems remain far from statistical equilibrium.     

Charged particle fluctuation in Au+Au collision

In this paper,we present the centrality,transverse momentum region and rapidity window size dependence of charged particle fluctuation from Relativistic Quantum Molecular Dynamics (RQMD) model.D Q,Γ Q and Φ Q all depend on the rapidity windows we chosen.ν +-,dyn is a promising observable in experiments,it weakly depends on the acceptance.The beam energy dependence of ν +-,dyn has been studied to present baseline prediction for net charge fluctuations in experiments.     

Level structure of192Au and194Au

The level structure of the odd-odd isotopes¹⁹²Au and¹⁹⁴Au was investigated by in-beamγ-ray spectroscopy with the reaction^natIr(α, 3nγ). Several new energy levels could be established in both isotopes.     

Charged particle fluctuation in Au+Au collision

In this paper,we present the centrality,transverse momentum region and rapidity window size dependence of charged particle fluctuation from Relativistic Quantum Molecular Dynamics （RQMD） model.D Q,Γ Q and Φ Q all depend on the rapidity windows we chosen.ν ＋-,dyn is a promising observable in experiments,it weakly depends on the acceptance.The beam energy dependence of ν ＋-,dyn has been studied to present baseline prediction for net charge fluctuations in experiments.     

Au/Au2S复合纳米球壳微粒的发光特性

观测了金纳米球壳微粒（纳米级Au2S介质外包裹一层纳米级厚的金壳）的荧光光谱，与块状Au2S的荧光峰相比，金纳米球壳的荧光峰蓝移到蓝绿区域，蓝移的主要原因是核－壳纳米复合结构中的表面态和量子尺寸效应。     

Space-momentum correlations in 8 AGeV Au+Au collisions

Within the RQMD model, space-momentum correlations, i.e. the correlations between final momentum anisotropy and initial eccentricity, are studied for 8 AGeV Au＋Au events classified according to the multi-particle azimuthal correlations. The results show that the final elliptic flow fluctuations depend on the initial collision geometry. There are clear space-momentum correlations for nucleons during the whole dynamical evolution of the collisions.     

激光金等离子体中Au52+静态能级寿命的相对论多组态计算

根据扩展的相对论多组态Dirac-Fock理论,采用"多功能相对论原子结构程序(GRASP2)",计算类钴Au52+的能级寿命、能级宽度和光谱跃迁波长,计算所得波长值与实验结果符合较好.能级寿命与能级宽度的大小关系符合海森堡的能量与时间测不准原理.     

Space-momentum correlations in 8 AGeV Au+Au collisions

Within the RQMD model, space-momentum correlations, i.e. the correlations between final momentum anisotropy and initial eccentricity, are studied for 8 AGeV Au+Au events classified according to the multi-particle azimuthal correlations. The results show that the final elliptic flow fluctuations depend on the initial collision geometry. There are clear space-momentum correlations for nucleons during the whole dynamical evolution of the collisions.     

金等离子体中Au51+能级寿命的相对论多组态计算

根据扩展的相对论多组态 Dirac-Fock理论,采用"多功能相对论原子结构程序(Grasp2) ",选用二参数Fermi有限核模型计算类镍Au51+ 的能级寿命和能级宽度及光谱跃迁波长、跃迁几率和振子强度,计算所得波长值与实验值符合得很好,能级寿命与能级宽度的大小关系符合海森堡的能量与时间测不准原理.     

Λ-超子在RHIC的Au+Au碰撞中的整体极化

We present the Λ-hyperon global polarization in Au+Au collisions at s_NN=62GeV and 200GeV measured with the STAR detector at RHIC. The observed Λ-hyperon global polarization is consistent with zero, what is in agreement with recent measurements of Λ global polarization, as well as φ(1020) and K^*0(892) vector mesons spin alignment with respect to the reaction plane. The possible dependence of the global polarization on relative azimuthal angle between the orbital momentum of the system and the hyperon 3-momentum is discussed. The corresponding systematic uncertainty due to detector acceptance is found to be less than 20%.     

197Au Mössbauer study of Au/Ni and Au/Fe metallic superlattices

¹⁹⁷Au Mössbauer measurements have been performed for Au/Ni and Au/Fe metallic superlattices at below 75 K. For Au/Ni superlattices, the area ratio in a spectrum between a superlattice component and that of the pure Au buffer layer has been determined at 25, 50 and 75 K. From the area ratios, it is found that the recoil-free fraction of Au in Au(10 Å)/Ni(10 Å) is larger than that of the bulk Au, suggesting the existence of the supermodulus effect in this superlattice. The¹⁹⁷Au Mössbauer spectrum obtained from Au(5 Å)/Fe(8 Å) is entirely magnetic at 16 K, suggesting the existence of a magnetic hyperfine interaction at¹⁹⁷Au nuclei through the transferred electron spin polarization.     

Baryon rapidity loss in relativistic Au + Au collisions

An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that display a broad peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a stationary source at midrapidity decreases with increasing beam energy. The data suggest that the stopping is substantially less than complete at these energies.     

Relative Distribution of Au48 ～ Au52 in Au Plasma by Ionization Dynamics

The present work proposes a theoretical method called ionization dynamics to derive the ionic charge state distribution. Using relativistic quantum mechanics to calculate the energy level lifetime and average ionic lifetime of each ion, the first-order ionization rate constant can be obtained. Based on these data, from the solution of differential equations for consecutive-irreversible ionization reactions, one will be able to derive the ionic charge state distribution.The calculated average positive charge 49.24 of Au48 ～ Au52 and their relative distribution are in good agreement with the results of Lawrence Livermore National Laboratory.     

Charged-particle pseudorapidity distributions in Au+Au collisions at RHIC

Using the Glauber model, we present the formulas for calculating the numbers of participants, spectators and binary nucleon-nucleon collisions. Based on this work, we get the pseudorapidity distributions of charged particles as the function of the impact parameter in nucleus-nucleus collisions. The theoretical results agree well with the experimental observations made by the BRAHMS Collaboration in Au＋Au collisions at √^SNN=200 GeV in different centrality bins over the whole pseudorapidity range.     

Charged-particle pseudorapidity distributions in Au+Au collisions at RHIC

Using the Glauber model, we present the formulas for calculating the numbers of participants,spectators and binary nucleon-nucleon collisions. Based on this work, we get the pseudorapidity distributions of charged particles as the function of the impact parameter in nucleus-nucleus collisions. The theoretical results agree well with the experimental observations made by the BRAHMS Collaboration in Au+Au collisions at √SNN=200 GeV in different centrality bins over the whole pseudorapidity range.     

Electrical properties of Au–polystyrene–Au submicron structures

Received: 25 January 1998/Accepted: 28 May 1998