2,559 research outputs found

    Ω−\Omega^- and Ωˉ+\bar\Omega^+ production in Au+Au collisions at sNN\sqrt{s_{NN}} = 130 and 200 GeV

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    Mid-rapidity Omega and anti-Omega production in Au+Au collisions at RHIC is studied with the STAR experiment. We report preliminary results on yields and spectra at sNN\sqrt{s_{NN}} = 130 and 200 GeV. Production relative to negatively charged hadrons (h-) as well as thermal freeze-out and collective expansion are discussed.Comment: 4 pages, 5 figures, 1 table, Contribution to Quark Matter 2002, Nantes, France, July 200

    Relations entre l'ultrastructure des plastes et les phases du cycle végétatif des bourgeons latents de la vigne (Vitis vinifera L. var. Ugni blanc)

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    Relationships between the ultrastructure of plastids and the phases of the vegetative cycle of latent buds of the vine (Vitis vinifera L. var. Ugni blanc)Salient features in the development of plastids and starch of the central bud into dormant buds of the vine occur during the stages of dormancy called ,,entrée en dormance" and ,,levée de dormance". Prolamellar bodies differentiate into plastids during the first stage and starch is hydrolysed during the later one. Starch changes in the plastids of central buds occur in agreement with the changes of glucid amounts in shoots

    The STAR Silicon Strip Detector (SSD)

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    The STAR Silicon Strip Detector (SSD) completes the three layers of the Silicon Vertex Tracker (SVT) to make an inner tracking system located inside the Time Projection Chamber (TPC). This additional fourth layer provides two dimensional hit position and energy loss measurements for charged particles, improving the extrapolation of TPC tracks through SVT hits. To match the high multiplicity of central Au+Au collisions at RHIC the double sided silicon strip technology was chosen which makes the SSD a half million channels detector. Dedicated electronics have been designed for both readout and control. Also a novel technique of bonding, the Tape Automated Bonding (TAB), was used to fullfill the large number of bounds to be done. All aspects of the SSD are shortly described here and test performances of produced detection modules as well as simulated results on hit reconstruction are given.Comment: 11 pages, 8 figures, 1 tabl

    Estimations of Ωˉ+/Ω−\bar{\Omega}^+/\Omega^- at RHIC from a QGP Model with Diquarks

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    Assuming that axial-vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature TcT_c, baryons can be produced from quark-diquark interactions. In RHIC conditions (sNN=130GeV\sqrt{s_{NN}} = 130GeV and 200GeV200GeV), the ratio Ωˉ+/Ω−\bar{\Omega}^+/\Omega^- may be larger than 1, based on the concept that QGP with diquarks would exist. This unusual result might be a helpful evidence for QGP existing in RHIC.Comment: 6 pages, 1 figure. accepted by J.Phys.

    Hadron production in heavy ion collisions: Fragmentation and recombination from a dense parton phase

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    We discuss hadron production in heavy ion collisions at RHIC. We argue that hadrons at transverse momenta P_T < 5 GeV are formed by recombination of partons from the dense parton phase created in central collisions at RHIC. We provide a theoretical description of the recombination process for P_T > 2 GeV. Below P_T = 2 GeV our results smoothly match a purely statistical description. At high transverse momentum hadron production is well described in the language of perturbative QCD by the fragmentation of partons. We give numerical results for a variety of hadron spectra, ratios and nuclear suppression factors. We also discuss the anisotropic flow v_2 and give results based on a flow in the parton phase. Our results are consistent with the existence of a parton phase at RHIC hadronizing at a temperature of 175 MeV and a radial flow velocity of 0.55c.Comment: 25 pages LaTeX, 18 figures; v2: some references updated; v3: some typos fixe

    Hydrodynamic emission of strange and non-strange particles at RHIC and LHC

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    The hydrodynamic model is used to describe the single-particle spectra and elliptic flow of hadrons at RHIC and to predict the emission angle dependence of HBT correlations at RHIC and LHC energies.Comment: 6 pages LaTeX, 3 postscript figures. Proceedings for the conference "Strange Quark Matter 2003", Atlantic Beach, NC, March 12-17, 2003, to appear in J. Phys.

    TAB Bonded SSD Module for the STAR and ALICE Trackers

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    Presentation made at LEB99, 20-24 September 1999A novel compact detector module has been produced by the "IReS"-"Subatech"-"Thomson-CSF-Detexis" collaboration. It includes a Double-Sided (DS) Silicon Strip Detector (SSD) and the related Front End Electronics (FEE) located on two hybrids, one for the N side and one for the P side. Bumpless Tape Automated Bonding (TAB) is used to connect the detector to the hybrids by means of microcables with neither wirebonding nor pitch adapter. Each of the six dedicated ALICE128C FE chip [1], located on the hybrid, is TABed on identical single layer microcables, which connect its inputs to the DS SSD and its outputs to the hybrid [2]. These microcables are bent in order to fold over the two hybrids on the DS SSD. This module meets the specifications of two experiments, ALICE (A Large Ion Collider Experiment) on the LHC accelerator at CERN [3] and STAR (Solenoid Tracker At Rhic) on the RHIC accelerator at BNL (Brookhaven National Laboratory)[4]. It can be used with air cooling (STAR) as well as with water cooling (ALICE)[5]. This mechanically self-consistent FE module has been tested on the SPS beam at CERN. Preliminary results are presented

    Production test of microstrip detector and electronic frontend modules for the STAR and ALICE trackers

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    We revisit Shin et al.’s leakage-resilient password-based authenticated key establishment protocol (LR-AKEP) and the security model used to prove the security of LR-AKEP. By refining the Leak oracle in the security model, we show that LR-AKE (1) can, in fact, achieve a stronger notion of leakage-resilience than initially claimed and (2) also achieve an additional feature of traceability, not previously mentioned
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