3,134 research outputs found
Inelastic Diffraction at Heavy Ion Colliders
The heavy ion physics approach to global event characterization has led us to
instrument the forward region in the PHENIX experiment at RHIC. In heavy ion
collisions this coverage yields a measurement of the "spectator" energy and its
distribution about the beam direction. This energy flow is the basis of
event-by-event determination of the centrality and reaction plane which are key
to analyzing particle production in heavy ion collisions. These same tools have
also enabled a unique set of measurements on inelastic diffraction with proton,
deuteron and gold ion beams in the PHENIX experiment. We present first new
results on this topic and discuss briefly the opportunity for diffractive
physics with Heavy Ion beams at the LHC.Comment: RHIC overview talk presented at "Diffraction 2004" in Dorgali,
Sardegna, Ital
PHENIX measurement of jet properties and their modification in heavy-ion collisions
The properties of jets produced in p+p, d+Au and Au+Au collisions at
sqrt{s_NN}=200 GeV are studied using the method of two particle correlations.
The trigger particle is assumed to be a leading particle from a high p_T jet
while the associated particle is assumed to come from either the same jet or
the away jet. From the angular width and yield of the same and away side
correlation peaks, the parameters characterizing the jet properties are
extracted.Comment: 4 pages, 3 figures, contribution to the proceedings of the 17th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings
(Journal of Physics G
Results on Photon Production in Au+Au Collisions at RHIC
The status of the search for direct photons in Au+Au collisions at sqrt{s_NN}
= 130 GeV and sqrt{s_NN} = 200 GeV with the PHENIX experiment is presented.
Within errors, no excess of direct photons was found in a first analysis pass
done on a limited data set. Significantly reduced systematic and statistical
uncertainties are expected in future analyses.Comment: 4 pages, 3 figures. Talk presented at the Quark Matter 2002
conference, Nantes, France, July 18-24, 2002. To appear in the proceedings
(Nucl. Phys. A
Two Particle Azimuthal Correlation Measurements in PHENIX
Two particle azimuthal correlation functions are presented for charged
hadrons produced in Au-Au collisions at RHIC sqrt(s_NN)=200 GeV.The correlation
functions indicate sizeable asymmetries and anisotropies. The trend of the
asymmetries is compatible with the presence of emission patterns associated
with mini-jets. The magnitude and the trend of the differential anisotropies
v_2(p_T) and v_2(N_Part), provide important model constraints.Comment: 4 pages 3 fig
Hadron production in the forward and backward rapidities in dAu collisions at RHIC
We have developed new techniques to detect hadrons with the PHENIX muon
spectrometers. This allows us to study the centrality dependent nuclear
modification factor with high hadrons in both forward (d
direction) and backward (Au direction) rapidities, , in dAu
collisions at . Preliminary results show a suppression
(enhancement) of high hadron production in central dAu
collisions relative to the peripheral one ( in centrality) at forward
(backward) rapidity.Comment: 4 pages, 4 figures, Quark Matter 2004 tal
Neutral Pion Distributions in PHENIX at RHIC
Transverse momentum spectra for identified 's in the range 1 GeV/c 4 GeV/c have been measured by the PHENIX experiment in Au-Au collisions
at GeV. The spectra from peripheral nuclear collisions are
consistent with the simple expectation of scaling the spectra from p+p
collisions by the average number of nucleon-nucleon binary collisions. The
spectra from central collisions and the ratio of central/peripheral spectra are
significantly suppressed when compared to point-like scaling.Comment: 6 pages, 3 figure
Hot Topics in Ultra-Peripheral Collisions
Ultra-peripheral collisions of relativistic heavy ions involve long-ranged
electromagnetic interactions at impact parameters too large for hadronic
interactions to occur. The nuclear charges are large; with the coherent
enhancement, the cross sections are also large. Many types of photonuclear and
purely electromagnetic interactions are possible. We present here an
introduction to ultra-peripheral collisions, and present four of the most
compelling physics topics. This note developed from a discussion at a workshop
on ``Electromagnetic Probes of Fundamental Physics,'' in Erice, Italy, Oct.
16-21, 2001.Comment: 7 pages, with 3 figures. This developed from a discussion at the
workshop on "Electromagnetic Probes of Fundamental Physics," Oct. 16-21,
Erice, Ital
Photoproduction at collider energies: from RHIC and HERA to the LHC
We present the mini-proceedings of the workshop on ``Photoproduction at
collider energies: from RHIC and HERA to the LHC'' held at the European Centre
for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento)
from January 15 to 19, 2007. The workshop gathered both theorists and
experimentalists to discuss the current status of investigations of high-energy
photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as
well as preparations for extension of these studies at the LHC. The main
physics topics covered were: (i) small- QCD in photoproduction studies with
protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus
collisions, (ii) hard diffraction physics at hadron colliders, and (iii)
photon-photon collisions at very high energies: electroweak and beyond the
Standard Model processes. These mini-proceedings consist of an introduction and
short summaries of the talks presented at the meeting
Point-to-point readout for the ALICE EMCal detector
AbstractIt is anticipated that the LHC will deliver Pb+Pb collisions at a minimum bias interaction rate of about 50kHz after the second long shutdown of the LHC in 2018. This will be roughly two orders of magnitude greater than the current data recording rate capability of the ALICE experiment. Therefore a major upgrade of the ALICE detector is planned for the next shutdown to enable ALICE to record data at the full Pb+Pb minimum bias interaction rate delivered by the LHC. A new point-to-point readout system for the electromagnetic calorimeter (EMCal) of ALICE has been developed, to replace the legacy readout bus, that essentially accomplishes this goal, and is being installed during the current LHC shutdown (2013–2014). The new readout uses the existing EMCal front end electronics yet provides more than an order of magnitude decrease in the readout time, to about 21μs, with modest cost and effort
Search for direct photons in p+Pb and p+C collisions at sqrt(sNN) = 17.4 GeV
Upper limits on direct photon production were determined as a function of the
transverse momentum for 0.7 < pT <= 3.2 GeV/c with the WA98 experiment in p+C
and p+Pb collisions at sqrt(sNN) = 17.4 GeV. The results are compared to direct
photon measurements in Pb+Pb collisions at sqrt(sNN) = 17.3 GeV by WA98.
Implications for a possible thermal direct photon contribution are discussed.Comment: 4 pages, 3 figures, to appear in the proceedings of the Quark Matter
2008 conference, Jaipur, India, 4-10 Feb 200
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