631 research outputs found
P02.119. Cognitively-Based Compassion Training reduces peripheral inflammation in adolescents in foster care with high rates of early life adversity
Deuteron and antideuteron production in Au+Au collisions at sqrt(s_NN)=200 GeV
The production of deuterons and antideuterons in the transverse momentum
range 1.1 < p_T < 4.3 GeV/c at mid-rapidity in Au + Au collisions at
sqrt(s_NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A
coalescence analysis comparing the deuteron and antideuteron spectra with those
of protons and antiprotons, has been performed. The coalescence probability is
equal for both deuterons and antideuterons and increases as a function of p_T,
which is consistent with an expanding collision zone. Comparing (anti)proton
yields p_bar/p = 0.73 +/- 0.01, with (anti)deuteron yields: d_bar/d = 0.47 +/-
0.03, we estimate that n_bar/n = 0.64 +/- 0.04.Comment: 326 authors, 6 pages text, 5 figures, 1 Table. Submitted to PRL.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Centrality dependence of charged hadron production in deuteron+gold and nucleon+gold collisions at sqrt(s_NN)=200 GeV
We present transverse momentum (p_T) spectra of charged hadrons measured in
deuteron-gold and nucleon-gold collisions at \sqrts = 200 GeV for four
centrality classes. Nucleon-gold collisions were selected by tagging events in
which a spectator nucleon was observed in one of two forward rapidity
detectors. The spectra and yields were investigated as a function of the number
of binary nucleon-nucleon collisions, \nu, suffered by deuteron nucleons. A
comparison of charged particle yields to those in p+p collisions show that the
yield per nucleon-nucleon collision saturates with \nu for high momentum
particles. We also present the charged hadron to neutral pion ratios as a
function of p_T.Comment: 330 authors, 15 pages text, 16 figures, 3 tables. Submitted to Phys.
Rev. Lett. v2 has minor changes to reflect revisions during review process.
Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Mid-Rapidity Direct-Photon Production in p+p Collisions at sqrt(s) = 200 GeV
A measurement of direct photons in p+p collisions at sqrt(s)=200 GeV is
presented. A photon excess above background from pi^0 --> gamma+gamma, eta -->
gamma+gamma, and other decays is observed in the transverse momentum range 5.5
< p_T < 7 GeV/c. The result is compared to a next-to-leading-order perturbative
QCD calculation. Within errors, good agreement is found between the QCD
calculation and the measured result.Comment: 330 authors, 7 pages text, RevTeX, 2 figures, 2 tables. Submitted to
Physical Review D. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
Azimuthal Angle Correlations for Rapidity Separated Hadron Pairs in d+Au Collisions at sqrt(s_NN) = 200 GeV
We report on two-particle azimuthal angle correlations between charged
hadrons at forward/backward (deuteron/gold going direction) rapidity and
charged hadrons at mid-rapidity in deuteron-gold (d+Au) and proton-proton (p+p)
collisions at sqrt(s_NN) = 200 GeV. Jet structures are observed in the
correlations which we quantify in terms of the conditional yield and angular
width of away side partners. The kinematic region studied here samples partons
in the gold nucleus carrying nucleon momentum fraction x~0.1 to x~0.01. Within
this range, we find no x dependence of the jet structure in d+Au collisions.Comment: 330 authors, 6 pages text, 4 figures, no tables. Submitted to Phys.
Rev. Lett. Plain text data tables for the points plotted in figures for this
and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Suppressed pi^0 Production at Large Transverse Momentum in Central Au+Au Collisions at sqrt(s_NN) = 200 GeV
Transverse momentum spectra of neutral pions in the range 1 < p_T < 10 GeV/c
have been measured at mid-rapidity by the PHENIX experiment at RHIC in Au+Au
collisions at sqrt(s_NN) = 200 GeV. The pi^0 multiplicity in central reactions
is significantly below the yields measured at the same sqrt(s_NN) in peripheral
Au+Au and p+p reactions scaled by the number of nucleon-nucleon collisions. For
the most central bin, the suppression factor is ~2.5 at p_T = 2 GeV/c and
increases to ~4-5 at p_T ~= 4 GeV/c. At larger p_T, the suppression remains
constant within errors. The deficit is already apparent in semi-peripheral
reactions and increases smoothly with centrality.Comment: 326 authors, 6 pages text, RevTeX, 3 figures, 2 tables. Submitted to
PRL. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Transverse-energy distributions at midrapidity in , Au, and AuAu collisions at --200~GeV and implications for particle-production models
Measurements of the midrapidity transverse energy distribution, d\Et/d\eta,
are presented for , Au, and AuAu collisions at
GeV and additionally for AuAu collisions at
and 130 GeV. The d\Et/d\eta distributions are first
compared with the number of nucleon participants , number of
binary collisions , and number of constituent-quark participants
calculated from a Glauber model based on the nuclear geometry. For
AuAu, \mean{d\Et/d\eta}/N_{\rm part} increases with , while
\mean{d\Et/d\eta}/N_{qp} is approximately constant for all three energies.
This indicates that the two component ansatz, , which has been used to represent
distributions, is simply a proxy for , and that the term
does not represent a hard-scattering component in distributions. The
distributions of AuAu and Au are then calculated from
the measured distribution using two models that both reproduce
the AuAu data. However, while the number-of-constituent-quark-participant
model agrees well with the Au data, the additive-quark model does not.Comment: 391 authors, 24 pages, 19 figures, and 15 Tables. Submitted to Phys.
Rev. C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are publicly available at
http://www.phenix.bnl.gov/papers.htm
Scaling properties of proton and anti-proton production in sqrt(s_NN) = 200 GeV Au + Au collisions
We report on the yield of protons and anti-protons, as a function of
centrality and transverse momentum, in Au+Au collisions at sqrt(s_NN) = 200 GeV
measured at mid-rapidity by the PHENIX experiment at RHIC. In central
collisions at intermediate transverse momenta (1.5 < p_T < 4.5 GeV/c) a
significant fraction of all produced particles are protons and anti-protons.
They show a centrality-scaling behavior different from that of pions. The
p-bar/pion and p/pion ratios are enhanced compared to peripheral Au+Au, p+p,
and electron+positron collisions. This enhancement is limited to p_T < 5 GeV/c
as deduced from the ratio of charged hadrons to pi^0 measured in the range 1.5
< p_T < 9 GeV/c.Comment: 325 authors, 6 pages text, 4 figures, RevTeX 4. Minor changes to text
and figures to meet PRL length restrictions; no changes to figures;
resubmitted to PRL. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm
J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV
We present measurements of the J/psi invariant yields in sqrt(s_NN)=39 and
62.4 GeV Au+Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields
are presented as a function of both collision centrality and transverse
momentum. Nuclear modifications are obtained for central relative to peripheral
Au+Au collisions (R_CP) and for various centrality selections in Au+Au relative
to scaled p+p cross sections obtained from other measurements (R_AA). The
observed suppression patterns at 39 and 62.4 GeV are quite similar to those
previously measured at 200 GeV. This similar suppression presents a challenge
to theoretical models that contain various competing mechanisms with different
energy dependencies, some of which cause suppression and others enhancement.Comment: 365 authors, 10 pages, 11 figures, 4 tables. Submitted to Phys. Rev.
C. Plain text data tables for the points plotted in figures for this and
previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
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