232 research outputs found

    E-Waste Recycling and Related Social Issues in China

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    AbstractChina has set a goal of establishing a Circular Economy policy for recycling resources in the near future. To further efforts to build a circular society, we analyzed the current status of E-waste recycling and related social issues, including the case of Guiyu town. Some policy suggestions on establishing recycling systems are recommended

    Propylene Carbonate Reexamined: Mode-Coupling β\beta Scaling without Factorisation ?

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    The dynamic susceptibility of propylene carbonate in the moderately viscous regime above TcT_{\rm c} is reinvestigated by incoherent neutron and depolarised light scattering, and compared to dielectric loss and solvation response. Depending on the strength of α\alpha relaxation, a more or less extended β\beta scaling regime is found. Mode-coupling fits yield consistently λ=0.72\lambda=0.72 and Tc=182T_{\rm c}=182 K, although different positions of the susceptibility minimum indicate that not all observables have reached the universal asymptotics

    Partial Wave Analysis of J/ψγ(K+Kπ+π)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

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    BES data on J/ψγ(K+Kπ+π)J/\psi \to \gamma (K^+K^-\pi^+\pi^-) are presented. The KKˉK^*\bar K^* contribution peaks strongly near threshold. It is fitted with a broad 0+0^{-+} resonance with mass M=1800±100M = 1800 \pm 100 MeV, width Γ=500±200\Gamma = 500 \pm 200 MeV. A broad 2++2^{++} resonance peaking at 2020 MeV is also required with width 500\sim 500 MeV. There is further evidence for a 2+2^{-+} component peaking at 2.55 GeV. The non-KKˉK^*\bar K^* contribution is close to phase space; it peaks at 2.6 GeV and is very different from KKˉK^{*}\bar{K^{*}}.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

    Single Spin Asymmetry ANA_N in Polarized Proton-Proton Elastic Scattering at s=200\sqrt{s}=200 GeV

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    We report a high precision measurement of the transverse single spin asymmetry ANA_N at the center of mass energy s=200\sqrt{s}=200 GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The ANA_N was measured in the four-momentum transfer squared tt range 0.003t0.0350.003 \leqslant |t| \leqslant 0.035 \GeVcSq, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of ANA_N and its tt-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this s\sqrt{s}, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure

    Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV

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    We present the first measurement of directed flow (v1v_1) at RHIC. v1v_1 is found to be consistent with zero at pseudorapidities η\eta from -1.2 to 1.2, then rises to the level of a couple of percent over the range 2.4<η<42.4 < |\eta| < 4. The latter observation is similar to data from NA49 if the SPS rapidities are shifted by the difference in beam rapidity between RHIC and SPS. Back-to-back jets emitted out-of-plane are found to be suppressed more if compared to those emitted in-plane, which is consistent with {\it jet quenching}. Using the scalar product method, we systematically compared azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure

    Azimuthal anisotropy: the higher harmonics

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    We report the first observations of the fourth harmonic (v_4) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding

    Partonic flow and ϕ\phi-meson production in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

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    We present first measurements of the ϕ\phi-meson elliptic flow (v2(pT)v_{2}(p_{T})) and high statistics pTp_{T} distributions for different centralities from sNN\sqrt{s_{NN}} = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v2v_{2} of the ϕ\phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Ω\Omega to those of the ϕ\phi as a function of transverse momentum is consistent with a model based on the recombination of thermal ss quarks up to pT4p_{T}\sim 4 GeV/cc, but disagrees at higher momenta. The nuclear modification factor (RCPR_{CP}) of ϕ\phi follows the trend observed in the KS0K^{0}_{S} mesons rather than in Λ\Lambda baryons, supporting baryon-meson scaling. Since ϕ\phi-mesons are made via coalescence of seemingly thermalized ss quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR

    Plasma Wakefield Acceleration with a Modulated Proton Bunch

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    The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.Comment: 9 pages, 7 figure

    The energy dependence of ptp_t angular correlations inferred from mean-ptp_{t} fluctuation scale dependence in heavy ion collisions at the SPS and RHIC

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    We present the first study of the energy dependence of ptp_t angular correlations inferred from event-wise mean transverse momentum fluctuations in heavy ion collisions. We compare our large-acceptance measurements at CM energies $\sqrt{s_{NN}} =$ 19.6, 62.4, 130 and 200 GeV to SPS measurements at 12.3 and 17.3 GeV. $p_t$ angular correlation structure suggests that the principal source of $p_t$ correlations and fluctuations is minijets (minimum-bias parton fragments). We observe a dramatic increase in correlations and fluctuations from SPS to RHIC energies, increasing linearly with $\ln \sqrt{s_{NN}}$ from the onset of observable jet-related fluctuations near 10 GeV.Comment: 10 pages, 4 figure
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