A. D. Frawley

Heavy flavor in heavy-ion collisions at RHIC and RHIC II

Abstract In the initial years of operation, experiments at the Relativistic Heavy Ion Collider (RHIC) have identified a new form of matter formed in nucleus–nucleus collisions at energy densities more than 100 times that of a cold atomic nucleus. Measurements and comparison with relativistic hydrodynamic models indicate that the matter thermalizes in an unexpectedly short time, has an energy density at least 15 times larger than needed for color deconfinement, has a temperature about twice the critical temperature predicted by lattice QCD, and appears to exhibit collective motion with ideal hydrodynamic properties–a “perfect liquid” that appears to flow with a near-zero viscosity to entropy ratio–lower than any previously observed fluid and perhaps close to a universal lower bound. However, a fundamental understanding of the medium seen in heavy-ion collisions at RHIC does not yet exist. The most important scientific challenge for the field in the next decade is the quantitative exploration of the new state of nuclear matter. That will require new data that will, in turn, require enhanced capabilities of the RHIC detectors and accelerator. In this report we discuss the scientific opportunities for an upgraded RHIC facility–RHIC II–in conjunction with improved capabilities of the two large RHIC detectors, PHENIX and STAR. We focus solely on heavy flavor probes. Their production rates are calculable using the well-established techniques of perturbative QCD and their sizable interactions with the hot QCD medium provide unique and sensitive measurements of its crucial properties making them one of the key diagnostic tools available to us.

Narrowing the uncertainty on the total charm cross section and its effect on the J / ψ cross section

We explore the available parameter space that gives reasonable fits to the total charm cross section to make a better estimate of its true uncertainty. We study the effect of the parameter choices on the energy dependence of the J/\psi\ cross section.

PHENIX central arm particle ID detectors

Abstract The Ring-Imaging Cherenkov (RICH) and the Time-of-Flight (ToF) systems provide identification of charged particles for the PHENIX central arm. The RICH is located between the inner and outer tracking units and is one of the primary devices for identifying electrons among the very large number of charged pions. The ToF is used to identify hadrons and is located between the most outer pad chamber (PC3) and the electromagnetic calorimeter. A Time Zero (T0) counter that enhances charged particle measurements in p–p collisions is described. Details of the construction and performance of both the RICH, ToF and T0 are given along with typical results from the first PHENIX data taking run.

Impact-parameter dependence of the nuclear modification of J/ψ production in d+Au collisions at √[sNN]=200 GeV

The centrality dependence of sqrt(s_NN)= 200 GeV d+Au {J/\psi} data, measured in 12 rapidity bins that span -2.2 < y < 2.4, has been fitted using a model containing an effective absorption cross section combined with EPS09 NLO shadowing. The centrality dependence of the shadowing contribution was allowed to vary nonlinearly, employing a variety of assumptions, in an effort to explore the limits of what can be determined from the data. The impact parameter dependencies of the effective absorption cross section and the shadowing parameterization are sufficiently distinct to be determined separately. It is found that the onset of shadowing is a highly nonlinear function of impact parameter. The mid and backward rapidity absorption cross sections are compared with lower energy data and, for times of 0.05 fm/c or greater, data over a broad range of collision energies and rapidities are well described by a model in which the absorption cross section depends only on time spent in the nucleus.

Inclusive soft pion production from 12.3-Gev/c and 17.5-GeV/c protons on Be, Cu and Au

Differential cross-sections are presented for the inclusive production of charged pions in the momentum range 0.1 to 1.2 GeV/c in interactions of 12.3 and 17.5 GeV/c protons with Be, Cu, and Au targets. The measurements were made by Experiment 910 at the Alternating Gradient Synchrotron in Brookhaven National Laboratory. The cross-sections are presented as a function of pion total momentum and production polar angle

Heavy-flavor production and medium properties in high-energy nuclear collisions --What next?

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Measuring centrality with slow protons in proton-nucleus collisions at 18 GeV/c

with respect to the beam.

Ring imaging Cherenkov detector of PHENIX experiment at RHIC

Abstract.Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-Dynamics (QCD). Recent results from experiments and theoretical developments regarding open and hidden heavy-flavor dynamics have been debated at the Lorentz Workshop Tomography of the Quark-Gluon Plasma with Heavy Quarks, which was held in October 2016 in Leiden, The Netherlands. In this contribution, we summarize identified common understandings and developed strategies for the upcoming five years, which aim at achieving a profound knowledge of the dynamical properties of the quark-gluon plasma.

12C + 7Li Reaction measurements and the 12C(7Li, t)16O reaction

Experiment E910 has measured slow protons and deuterons from collisions of 18 GeV/c protons with Be, Cu, and Au targets at the BNL AGS. These correspond to the {open_quotes}grey tracks{close_quotes} first observed in emulsion experiments. We report on their momentum and angular distributions and investigate their use in measuring the centrality of a collision, as defined by the mean number of projectile-nucleon interactions. The relation between the measured N{sub grey} and the mean number of interactions {bar {nu}}(N{sub grey}) is studied using several simple models, one newly proposed, as well as the RQMD event generator. RQMD is shown to reproduce the N{sub grey} distribution, and exhibits a dependence of N{sub grey} on centrality that is similar to the behavior of the simple models. We find a strong linear dependence of {ovr N{sub grey}} on {nu}, with a constant of proportionality that varies with target. For the Au target, we report a relative systematic error for extracting {bar {nu}}(N{sub grey}) that lies between 10 and 20h{percent} over all N{sub grey}. {copyright} {ital 1999} {ital The American Physical Society}

A spiral-resonator beam phase detector

Abstract The RICH detector of the PHENIX experiment at RHIC is currently under construction. Its main function is to identity electron tracks in a very high particle density, about 1000 charged particles per unit rapidity, expected in the most violent collisions at RHIC. The design and construction status of the detector and its expected performance are described.