A golden age for heavy-quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The ...early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the
B
-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau–Charm factories, JLab, the ILC, and beyond. The list of newly found conventional states expanded to include
h
c
(1
P
),
χ
c
2
(2
P
),
, and
η
b
(1
S
). In addition, the unexpected and still-fascinating
X
(3872) has been joined by more than a dozen other charmonium- and bottomonium-like “
XYZ
” states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new states unleashed a flood of theoretical investigations into new forms of matter such as quark–gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of
,
, and
bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. Lattice QCD has grown from a tool with computational possibilities to an industrial-strength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark–gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.
PHENIX central arm particle ID detectors Aizawa, M.; Akiba, Y.; Begay, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2003, Letnik:
499, Številka:
2
Journal Article
Recenzirano
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.
Ring imaging Cherenkov detector of PHENIX experiment at RHIC Akiba, Y.; Begay, R.; Burward-Hoy, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/1999, Letnik:
433, Številka:
1
Journal Article
Recenzirano
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.
The PHENIX ring imaging Cherenkov detector Akiba, Y; Begay, R; Burwood-Hoy, J ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2000, Letnik:
453, Številka:
1
Journal Article
Recenzirano
The PHENIX experiment at RHIC is primarily a lepton and photon detector. Electron detection takes place in the two central arms of PHENIX, with the primary electron identifier in each arm being a ...ring imaging Cherenkov detector. This paper contains a description of the two identical RICH detectors and of their expected performance.
A UV-sensitive wire chamber with a CsI photocathode was tested to examine the overall performance, and the quantum efficiency of the cathode. The chamber is operated as a parallel plate avalanche ...counter (PPAC) at low pressure (35 Torr ethane). A detailed discussion of our “implementation-ready” design is followed by a description of the CsI-coating procedure. We measured, on the bench, a quantum efficiency of 23±4% at 188 nm. The UV-chamber was tested as a RICH (ring imaging Cherenkov) focal plane detector using a 1 GeV/
c electron beam from the AGS at BNL. The measured yields of photoelectrons from Cherenkov light were 3.3, 5.9 and 7.4 photoelectrons per ring per meter using nitrogen, methane and ethane radiators. The quantum efficiency measured on the bench and deduced from the beam test is in good agreement with the literature. These results are quite promising for building a large area RICH focal plane using this technique, e.g. in the PHENIX RICH detector to be built at RHIC.
The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and K(S) dn/dy distributions from 17.5 GeV/ c p-Au collisions are shown ...as a function of "grey" track multiplicity and the estimated number of collisions, nu, made by the proton. The nu dependence of the Lambda yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for nu</=5 and saturating for larger nu. A slower growth in K(S) multiplicity with nu is observed, consistent with a weaker nu dependence of K production than YK production.
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