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The Fourier harmonics, v 2 and v 3 of negative pions are measured at center-of-mass energy per nucleon pair of s NN = 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0–30% central PbAu collisions with a mean centrality of 5.5%. The analysis is performed in two centrality bins as a function of the transverse momentum p T from 0.05 GeV/ c to more than 2 GeV/ c . This is the first measurement of the v 3 1 / 3 / v 2 1 / 2 ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For p T above 0.5 GeV/ c , the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.

Abstract The Fourier harmonics,$$v_2$$v 2 and$$v_3$$v 3 of negative pions are measured at center-of-mass energy per nucleon pair of$$\\sqrt{s_{\\textrm{NN}}}$$s NN = 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0–30% central PbAu collisions with a mean centrality of 5.5%. The analysis is performed in two centrality bins as a function of the transverse momentum$$\\mathrm {p_{\\textrm{T}}}$$p T from 0.05 GeV/c to more than 2 GeV/c. This is the first measurement of the$$v^{1/3}_{3}/v^{1/2}_{2}$$v 3 1 / 3 / v 2 1 / 2 ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For$$\\mathrm {p_{\\textrm{T}}}$$p T above 0.5 GeV/c, the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.

AbstractOne of the main tracking detectors of the forthcoming ALICE Experiment at the LHC is a cylindrical Time Projection Chamber (TPC) with an expected data volume of about 75 MByte per event. This data volume, in combination with the presumed maximum bandwidth of 1.2 GByte/s to the mass storage system, would limit the maximum event rate to 20 Hz. In order to achieve higher event rates, online data processing has to be applied. This implies either the detection and read-out of only those events which contain interesting physical signatures or an efficient compression of the data by modeling techniques. In order to cope with the anticipated data rate, massive parallel computing power is required. It will be provided in form of a clustered farm of SMP-nodes, based on off-the-shelf PCs, which are connected with a high bandwidth low overhead network. This High-Level Trigger (HLT) will be able to process a data rate of 25 GByte/s online. The front-end electronics of the individual sub-detectors is connected to the HLT via an optical link and a custom PCI card which is mounted in the clustered PCs. The PCI card is equipped with an FPGA necessary for the implementation of the PCI-bus protocol. Therefore, this FPGA can also be used to assist the host processor with first-level processing. The first-level processing done on the FPGA includes conventional cluster-finding for low multiplicity events and local track finding based on the Hough Transformation of the raw data for high multiplicity events.PACS: 07.05.-t Computers in experimental physics – 07.05.Hd Data acquisition: hardware and software – 29.85.+c Computer data analysis

The effects of pH on the action of sodium azide, a cytochome-oxidase inhibitor, and salicylhydroxamate (SHAM), an alternative respiration inhibitor, on the respiration of dormant seeds of wild oat (Avena fatua L.; line AN-51) were studied. While pH had little effect on seed respiration in controls, it strongly affected the activity of azide. One mM azide inhibited seed respiration at pH5, but stimulated it at pH 7. SHAM (10 mM) completely inhibited the stimulation of respiration by 1 mM azide in an unbuffered medium, but failed to do so when the medium was buffered at pH 7. In unbuffered medium, 10 mM SHAM actually augmented the stimulation of respiration by 0.25 mM azide to the same degree as when the azide solution was acidified to mimic the pH change incurred with dissolution of 10 mM SHAM. These results suggest that the inhibitory effect of SHAM on the action of azide in an unbuffered system may in part be due to its acidification of the incubation medium rather than by the inhibition of alternative oxidase. Lower pH favours the formation of the undissociated hydrazoate molecules causing greater inhibition of cytochrome-oxidase and other azide-sensitive enzymes.

The effects of sodium azide, potassium cyanide (cytochrome oxidase inhibitors), and salicylhydroxamic acid (SHAM; an alternative respiration inhibitor) on germination and respiration of Avena fatua L. seeds were studied. Azide and cyanide released seed dormancy at similar concentrations and treatment durations. Cyanide, however, stimulated germination of seeds with little after-ripening, whereas azide had no effect under similar conditions unless the seeds were after-ripened for several months; the duration of after-ripening required for seeds to respond to azide varied with seed batch. There was also a greater lag prior to germination in the case of azide, compared to cyanide treated seeds. SHAM inhibited the stimulation of germination and respiration by azide, but not by cyanide. Furthermore, respiration induced by azide or cyanide could not be inhibited by the subsequent application of SHAM. These findings suggest that the respiration stimulated by azide and cyanide is not alternative (SHAM-sensitive) and, therefore, this respiratory pathway cannot be involved in the stimulation of germination by cytochrome oxidase inhibitors. While embryos excised from control, azide or cyanide pretreated seeds had the capacity to perform alternative respiration, the actual contribution of this pathway was negligible. A large proportion of respiration of embryos excised from azide or cyanide pretreated seeds was residual, i.e. insensitive to both SHAM and cyanide.

A study of elliptic flow and two-particle azimuthal correlations of charged particles (\\(0.5 < p_{{\\text{T}}} < 2.5\\) GeV/c) and high-\\(p_{\\rm T}\\) pions (\\(1.2 < p_{{\\text{T}}} < 3.5\\) GeV/c) in Pb + Au collisions at 158A GeV/c, close to midrapidity, is presented. Elliptic flow (v2) rises linearly with \\(p_{\\rm T}\\) to a value of about 10\\(\\%\\) at 2 GeV/c. Beyond \\(p_{\\rm T}\\approx\\) 1.5 GeV/c, the slope decreases and possibly indicates a v2 saturation at high \\(p_{\\rm T}\\). Two-pion azimuthal anisotropies for \\(p_{\\rm T} > \\) 1.2 GeV/c exceed the v2 values by about 60\\(\\%\\) in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the near-side peak remains constant with centrality 0.23\\(\\pm\\)0.03 rad, as expected for fragmentation, the away-side peak experiences broadening and disappears in central collisions.

The Fourier harmonics, \\(v_2\\) and \\(v_3\\) of negative pions are measured at center-of-mass energy per nucleon pair of \\(s_NN\\)= 17.3 GeV around midrapidity by the CERES/NA45 experiment at the CERN SPS in 0--30\\% central PbAu collisions with a mean centrality of 5.5\\%. The analysis is performed in two centrality bins as a function of the transverse momentum \\(p_T\\) from 0.05 GeV/\\(c\\) to more than 2 GeV/\\(c\\). This is the first measurement of the \\(v^1/3_3/v^1/2_2\\) ratio as a function of transverse momentum at SPS energies, that reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. For \\(p_T\\) above 0.5 GeV/\\(c\\), the ratio is nearly flat in accordance with the hydrodynamic prediction and as previously observed by the ATLAS and ALICE experiments at the much higher LHC energies. The results are also compared with the SMASH-vHLLE hybrid model predictions, as well as with the SMASH model applied alone.

Differential elliptic flow spectra v2(pT) of \\pi-, K0short, p, \\Lambda have been measured at \\sqrt(s NN)= 17.3 GeV around midrapidity by the CERN-CERES/NA45 experiment in mid-central Pb+Au collisions (10% of \\sigma(geo)). The pT range extends from about 0.1 GeV/c (0.55 GeV/c for \\Lambda) to more than 2 GeV/c. Protons below 0.4 GeV/c are directly identified by dE/dx. At higher pT, proton elliptic flow v2(pT) is derived as a constituent, besides \\pi+ and K+, of the elliptic flow of positive pion candidates. The retrieval requires additional inputs: (i) of the particle composition, and (ii) of v2(pT) of positive pions. For (i), particle ratios obtained by NA49 were adapted to CERES conditions; for (ii), the measured v2(pT) of negative pions is substituted, assuming \\pi+ and \\pi- elliptic flow magnitudes to be sufficiently close. The v2(pT) spectra are compared to ideal-hydrodynamics calculations. In synopsis of the series \\pi- - K0short - p - \\Lambda, flow magnitudes are seen to fall with decreasing pT progressively even below hydro calculations with early kinetic freeze-out (Tf= 160 MeV) leaving not much time for hadronic evolution. The proton v2(pT) data show a downward swing towards low pT with excursions into negative v2 values. The pion-flow isospin asymmetry observed recently by STAR at RHIC, invalidating in principle our working assumption, is found in its impact on proton flow bracketed from above by the direct proton flow data, and not to alter any of our conclusions. Results are discussed in perspective of recent viscous dynamics studies which focus on late hadronic stages.

The High Level Trigger (HLT) system of the ALICE experiment is an online event filter and trigger system designed for input bandwidths of up to 25 GB/s at event rates of up to 1 kHz. The system is designed as a scalable PC cluster, implementing several hundred nodes. The transport of data in the system is handled by an object-oriented data flow framework operating on the basis of the publisher-subscriber principle, being designed fully pipelined with lowest processing overhead and communication latency in the cluster. In this paper, we report the latest measurements where this framework has been operated on five different sites over a global north-south link extending more than 10,000 km, processing a ``real-time'' data flow.

We present results of a two-pion correlation analysis performed with the Au+Pb collision data collected by the upgraded CERES experiment in the fall of 2000. The analysis was done in bins of the reaction centrality and the pion azimuthal emission angle with respect to the reaction plane. The pion source, deduced from the data, is slightly elongated in the direction perpendicular to the reaction plane, similarly as was observed at the AGS and at RHIC.