Full-size (22×22×180
mm
3) A
lice crystals were delivered by “North Crystals” company, Apatity, Russia. These crystals were tested with test benches, specially built for measurements of the crystals ...optical transmission and light yield. Beam-test results of different sets of 3×3 matrices with Hamamatsu APD light readout are presented. Data were taken at electron momenta from 600
MeV/
c up to 10
GeV/
c. Energy resolution and linearity curves are measured. The tests were carried out at the C
ern PS and SPS secondary beam-lines.
Extensive experimental data from high-energy nucleus-nucleus collisions were recorded using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). The comprehensive set of measurements ...from the first three years of RHIC operation includes charged particle multiplicities, transverse energy, yield ratios and spectra of identified hadrons in a wide range of transverse momenta (
p
T
), elliptic flow, two-particle correlations, nonstatistical fluctuations, and suppression of particle production at high
p
T
. The results are examined with an emphasis on implications for the formation of a new state of dense matter. We find that the state of matter created at RHIC cannot be described in terms of ordinary color neutral hadrons.
A large-scale prototype of the PHOS electromagnetic spectrometer, which is part of the ALICE detector, has been built and tested. This prototype has 256 detector channels and is operated at −25
°C. ...Each detector channel is a lead-tungstate crystal coupled to an Avalanche Photo-Diode with a low-noise preamplifier. The prototype includes a 16×16 crystal matrix, photo-detectors, analog and digital electronics, a thermo-stabilized cooling system, a light-emitting diode monitoring system, and a charged-particle detector acting as veto counter. Results of measurements using electron and hadron beams of the CERN PS and SPS accelerators are discussed, and the performance of the prototype is evaluated.
The PHENIX Electromagnetic Calorimeter (EMCal) is used to measure the spatial position and energy of electrons and photons produced in heavy ion collisions. It covers the full central spectrometer ...acceptance of 70°⩽
θ⩽110° with two walls, each subtending 90° in azimuth. One wall comprises four sectors of a Pb-scintillator sampling calorimeter and the other has two sectors of Pb-scintillator and two of a Pb-glass Cherenkov calorimeter. Both detectors have very good energy, spatial and timing resolution, while the Pb-scintillator excels in timing and the Pb-glass in energy measurements. Also, having two detectors with different systematics increases the confidence level of the physics results. Design and operational parameters of the Pb-scintillator, Pb-glass and special readout electronics for EMCal are presented and running experience during the first year of data taking with PHENIX is discussed. Some examples of data taken during the first run are shown.
Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions ...have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
Measurements of direct photon production in p + Pb and p + C collisions at root(NN)-N-s = 17.4 GeV are presented. Upper limits on the direct photon yield as a function of p(T) are derived and ...compared to the results for Pb + Pb collisions at root(NN)-N-s = 17.3 GeV. The production of the eta meson, which is an important input to the direct photon signal extraction, has been determined in the eta -> 2 gamma channel for p + C collisions at root(NN)-N-s = 17.4 GeV. (c) 2012 Elsevier B.V. All rights reserved.
Measurements of direct photon production in p+Pb and p+C collisions at sNN=17.4 GeV are presented. Upper limits on the direct photon yield as a function of pT are derived and compared to the results ...for Pb+Pb collisions at sNN=17.3 GeV. The production of the η meson, which is an important input to the direct photon signal extraction, has been determined in the η→2γ channel for p+C collisions at sNN=17.4 GeV.
Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at root s(NN) = 17.4 GeV at midrapidity (2.3 less than or similar to eta(lab)less than or similar to 3.0) over the ...range 0.7 less than or similar to p(T)less than or similar to 3.5 GeV/c. The spectra are compared to pi(0) spectra measured in Pb+Pb collisions at root s(NN) = 17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N-part less than or similar to 300), the yield of pi(0)'s with p(T)greater than or similar to 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N-coll), while for central Pb+Pb collisions with N-part greater than or similar to 350, the pi(0) yield is suppressed.
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