New results on Coulomb interaction effects in relativistic heavy ion collisions

The effects of the Coulomb interaction on charged pion production in Au+Au collisions at RHIC-BES energies are studied. From pT spectra of charged pions measured with STAR experiment, the negative-to-positive pion ratios as a function of transverse momentum are obtained. Based of these pion ratio the finalstate Coulomb interaction can be investigated. The “Coulomb kick” (a momentum change due to Coulomb interaction) and initial pion ratio for RHIC-BES energies (7.7 GeV, 11.5 GeV, 19.6 GeV, 27 GeV and 39 GeV) and various centrality classes are obtained. The energy and centrality dependence of the Coulomb kick is presented. These results are connected with the kinetic freeze-out dynamics

Predisposing conditions and outcome in adult patients with recurrent pneumococcal meningitis

Introduction: Recurrent pneumococcal meningitis is a relatively rare condition associated with predisposing factors. The objective of the study was to evaluate the characteristics and predisposing factors for recurrent pneumococcal meningitis in adults and compare them to patients with non-recurrent meningitis. Methods: A retrospective record review was performed of all patients hospitalized for pneumococcal meningitis in a large tertiary referral center, during a 10-year period. Results: We identified a total of 194 pneumococcal meningitis episodes in 182 patients. Thirty-eight (20%) meningitis episodes in 26 patients were recurrent. Anatomical defects and/or CSF leakage were present in 55% of recurrent pneumococcal meningitis vs. 10% of non-recurrent episodes (p<0.001). Impaired immune response was encountered in 41% non-recurrent meningitis vs 24% of recurrent episodes (p=0.02). Median age in patients with recurrent meningitis was 29 years, while patients with non-recurrent meningitis had a median age of 57 years (p<0.001). The in-hospital mortality was 3% in patients with recurrent meningitis vs 27% in patients with non-recurrent meningitis (p<0.001). An unfavorable outcome was more likely to occur in patients with advanced age and an impaired immune status. Conclusions: Patients with recurrent pneumococcal meningitis were younger, had less comorbidities and a better outcome

Centrality dependence of charged-particle pseudorapidity distributions from d+Au collisions at sqrt(s_{NN})=200 GeV

Charged-particle pseudorapidity densities are presented for the d+Au reaction at sqrt{s_{NN}}=200 GeV with -4.2 <= eta <= 4.2$. The results, from the BRAHMS experiment at RHIC, are shown for minimum-bias events and 0-30%, 30-60%, and 60-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semi-classical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt{s_{NN}}=19.4 GeV.Comment: 4 pages, 3figures; expanded discussion of uncertainties; added 60-80% centrality range; added additional discussion on centrality selection bia

Nuclear Stopping in Au+Au Collisions at sqrt(sNN) = 200 GeV

Transverse momentum spectra and rapidity densities, dN/dy, of protons, anti-protons, and net--protons (p-pbar) from central (0-5%) Au+Au collisions at sqrt(sNN) = 200 GeV were measured with the BRAHMS experiment within the rapidity range 0 < y < 3. The proton and anti-proton dN/dy decrease from mid-rapidity to y=3. The net-proton yield is roughly constant for y<1 at dN/dy~7, and increases to dN/dy~12 at y~3. The data show that collisions at this energy exhibit a high degree of transparency and that the linear scaling of rapidity loss with rapidity observed at lower energies is broken. The energy loss per participant nucleon is estimated to be 73 +- 6 GeV.Comment: 5 pages, 4 figure

Rapidity and centrality dependence of particle production for identified hadrons in Cu+Cu collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

The BRAHMS collaboration has measured transverse momentum spectra of pions, kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV. As the collisions become more central the collective radial flow increases while the temperature of kinetic freeze-out decreases. The temperature is lower and the radial flow weaker at forward rapidity. Pion and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are suppressed for central collisions relative to scaled $p+p$ collisions. This suppression, which increases as the collisions become more central is consistent with jet quenching models and is also present with comparable magnitude at forward rapidity. At such rapidities initial state effects may also be present and persistence of the meson suppression to high rapidity may reflect a combination of jet quenching and nuclear shadowing. The ratio of protons to mesons increases as the collisions become more central and is largest at forward rapidities.Comment: 19 pages, 11 figures and 6 table

High Pt Hadron Spectra at High Rapidity

We report the measurement of charged hadron production at different pseudo-rapidity values in deuteron+gold as well as proton+proton collisions at $sqrt{s_{NN}}$ = 200GeV at RHIC. The nuclear modification factors $R_{dAu}$ and $R_{cp}$ are used to investigate new behaviors in the deuteron+gold system as function of rapidity and the centrality of the collisions respectively.Comment: Nine pages 4 figures to be published in the QM2004 Proceedings, typos corrected and one reference adde