2,698 research outputs found
Traces of Thermalization at RHIC
I argue that measurements of Au+Au collisions at 20, 130 and 200 GeV of the
centrality dependence of the mean p_t together with p_t and net-charge
fluctuations reflect the approach to local thermal equilibrium.Comment: 4 pages, 4 eps figures, for proc. Quark Matter 2004, to be published
in J. Phys.
Recent high pT measurements in STAR
After five years of data taking, the STAR experiment at the Relativistic
Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise
measurements of particle production at high transverse momentum in p-p, d-Au,
and Au-Au collisions at sqrt(s) = 200 GeV. We review recent results on the
flavor dependence of high pT particle suppression and hadron particle spectra
at sqrt(s) = 62.4 GeV. New results on two-particle angular correlations for
identified trigger particles and for low momentum associated charged hadrons in
p-p and Au-Au as well as near-side correlations will be presented
and discussed.Comment: 5th International Conference on Physics and Astrophysics of Quark
Gluon Plasma, Calcutta. 8 pages, 10 figures, submitted to J. Phys. G: Nucl.
Part. Phy
Application of AIS Technology to Forest Mapping
Concerns about environmental effects of large scale deforestation have prompted efforts to map forests over large areas using various remote sensing data and image processing techniques. Basic research on the spectral characteristics of forest vegetation are required to form a basis for development of new techniques, and for image interpretation. Examination of LANDSAT data and image processing algorithms over a portion of boreal forest have demonstrated the complexity of relations between the various expressions of forest canopies, environmental variability, and the relative capacities of different image processing algorithms to achieve high classification accuracies under these conditions. Airborne Imaging Spectrometer (AIS) data may in part provide the means to interpret the responses of standard data and techniques to the vegetation based on its relatively high spectral resolution
Open heavy flavor production at RHIC
The study of heavy flavor production in relativistic heavy ion collisions is
an extreme experimental challenge but provides important information on the
properties of the Quark-Gluon Plasma (QGP) created in Au+Au collisions at RHIC.
Heavy-quarks are believed to be produced in the initial stages of the
collision, and are essential on the understanding of parton energy loss in the
dense medium created in such environment. Moreover, heavy-quarks can help to
investigate fundamental properties of QCD in elementary p+p collisions. In this
work we review recent results on heavy flavor production and their interaction
with the hot and dense medium at RHIC.Comment: Quark Matter 2006 proceedings, 8 pages, 5 figure
Heavy ion collisions: Correlations and Fluctuations in particle production
Correlations and fluctuations (the latter are directly related to the
2-particle correlations) is one of the important directions in analysis of
heavy ion collisions. At the current stage of RHIC exploration, when the
details matter, basically any physics question is addressed with help of
correlation techniques. In this talk I start with a general introduction to the
correlation and fluctuation formalism and discuss weak and strong sides of
different type of observables. In more detail, I discuss the two-particle
correlations/\mpt fluctuations. In spite of not observing any dramatic
changes in the event-by-event fluctuations with energy, which would indicate a
possible phase transition, such correlations measurements remain an interesting
and important subject, bringing valuable information. Lastly, I show how radial
flow can generate characteristic azimuthal, transverse momentum and rapidity
correlations, which could qualitatively explain many of recently observed
phenomena in nuclear collisions.Comment: 8 pages, 8 figures. Invited talk at 5th International Conference on
Physics and Astrophysics of Quark Gluon Plasma, February 8-12, 2005, Salt
Lake City, Kolkata, Indi
Particle dependence of elliptic flow in Au+Au collisions at 200 GeV
The elliptic flow parameter () for and
has been measured at mid-rapidity in Au + Au collisions at
GeV by the STAR collaboration. The values for both
and saturate at moderate , deviating
from the hydrodynamic behavior observed in the lower region. The
saturated values and the scales where the deviation begins are
particle dependent. The particle-type dependence of shows features
expected from the hadronization of a partonic ellipsoid by coalescence of
co-moving quarks. These results will be discussed in relation to the nuclear
modification factor () which has also been measured for and
by the STAR collaboration.Comment: 6 pages, 3 figures, Strange Quark Matter 2003 Conference (SQM 2003):
updated with 2 figures from original talk that did not appear in the journa
Event-by-Event Fluctuations at 40, 80, and 158 AGeV/c in Pb+Au Collisions
Event-by-event fluctuations of mean pt and net charge in 40, 80, and 158
AGeV/c Pb+Au collisions are presented. The observed dynamical mean pt
fluctuations in central events of about 1 % are very similar to results from
RHIC. The centrality dependence of mean pt fluctuations at 158 AGeV/c shows a
peculiar non-monotonic pattern with respect to the extrapolation from the
fluctuations measured in p+p collisions. Dynamical net charge fluctuations
smaller than the charge conservation limit are observed. After correction for
charge conservation, the measured fluctuation signal in central events is
comparable to RHIC results.Comment: 4 pages, 6 figures, proceedings of the Quark Matter 2004, in Oakland,
USA, to be published in Journal of Physics G: Nuclear and Particle Physic
Centrality dependence of spectra for identified hadrons in Au+Au and Cu+Cu collisions at GeV
The centrality dependence of transverse momentum spectra for identified
hadrons at midrapidity in Au+Au collisions at GeV is
systematically studied in a quark combination model. The
spectra of , , and in
different centrality bins and the nuclear modification factors () for
these hadrons are calculated. The centrality dependence of the average
collective transverse velocity for the hot and dense quark matter
is obtained in Au+Au collisions, and it is applied to a relative smaller Cu+Cu
collision system. The centrality dependence of spectra and
the for , and in Cu+Cu collisions at
GeV are well described. The results show that is only a function of the number of participants and it is
independent of the collision system.Comment: 7 pages, 6 figure
Strangeness production in jets from p+p \sqrt{s} = 200 GeV collisions
Measurements of strangeness production in jets help illuminate the QCD
mechanisms in fragmentation. Furthermore, they provide a crucial baseline for
heavy-ion studies where modifications in jet chemistry have recently been
predicted. We present new results on strange particle production in jets from
p+p \sqrt{s} = 200 GeV collisions measured by the STAR experiment. The momentum
distributions of the \Lambda, \bar{\Lambda} and K0Short particles are obtained
using various jet finding algorithms, and then compared to various models.
Strange particle ratios in jets are obtained and compared to values obtained
from the inclusive spectra. Finally, we show jets tagged with leading strange
baryons and mesons, in order to investigate whether gluon or quark jets can be
isolated in this way.Comment: 5 pages, 4 figures, Winter Workshop on Nuclear Dynamics 2010, Jamaic
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