343 research outputs found
Inclusive cross section and double helicity asymmetry for pi^0 production in p+p collisions at sqrt(s) = 62.4 GeV
The PHENIX experiment presents results from the RHIC 2006 run with polarized
proton collisions at sqrt(s) = 62.4 GeV for inclusive pi^0 production at
mid-rapidity. Unpolarized cross section results are measured for transverse
momenta p_T = 0.5 to 7 GeV/c. Next-to-leading order perturbative quantum
chromodynamics calculations are compared with the data, and while the
calculations are consistent with the measurements, next-to-leading logarithmic
corrections improve the agreement. Double helicity asymmetries A_LL are
presented for p_T = 1 to 4 GeV/c and probe the higher range of Bjorken_x of the
gluon (x_g) with better statistical precision than our previous measurements at
sqrt(s)=200 GeV. These measurements are sensitive to the gluon polarization in
the proton for 0.06 < x_g < 0.4.Comment: 387 authors from 63 institutions, 10 pages, 6 figures, 1 table.
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
Impairments in hearing and vision impact on mortality in older people: the AGES-Reykjavik Study.
To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files.
This article is open access.to examine the relationships between impairments in hearing and vision and mortality from all-causes and cardiovascular disease (CVD) among older people.population-based cohort study.the study population included 4,926 Icelandic individuals, aged ≥67 years, 43.4% male, who completed vision and hearing examinations between 2002 and 2006 in the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-RS) and were followed prospectively for mortality through 2009.participants were classified as having 'moderate or greater' degree of impairment for vision only (VI), hearing only (HI), and both vision and hearing (dual sensory impairment, DSI). Cox proportional hazard regression, with age as the time scale, was used to calculate hazard ratios (HR) associated with impairment and mortality due to all-causes and specifically CVD after a median follow-up of 5.3 years.the prevalence of HI, VI and DSI were 25.4, 9.2 and 7.0%, respectively. After adjusting for age, significantly (P < 0.01) increased mortality from all causes, and CVD was observed for HI and DSI, especially among men. After further adjustment for established mortality risk factors, people with HI remained at higher risk for CVD mortality [HR: 1.70 (1.27-2.27)], whereas people with DSI remained at higher risk of all-cause mortality [HR: 1.43 (1.11-1.85)] and CVD mortality [HR: 1.78 (1.18-2.69)]. Mortality rates were significantly higher in men with HI and DSI and were elevated, although not significantly, among women with HI.older men with HI or DSI had a greater risk of dying from any cause and particularly cardiovascular causes within a median 5-year follow-up. Women with hearing impairment had a non-significantly elevated risk. Vision impairment alone was not associated with increased mortality.National Institutes of Health, National Institute on Aging (NIA)
N01-AG-12100
NIA
Z01-AG007380
National Eye Institute (NEI)
ZIAEY000401
National Institute on Deafness and Other Communication Disorders (NIDCD) Division of Scientific Programs/IAA Y2-DC-1004-02
Hjartavernd (Icelandic Heart Association)
Althingi (Icelandic Parliament
A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay
We report a new measurement of electron antineutrino disappearance using the
fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight
antineutrino detectors were installed in the summer of 2012. Including the 404
days of data collected from October 2012 to November 2013 resulted in a total
exposure of 6.910 GW-ton-days, a 3.6 times increase over
our previous results. Improvements in energy calibration limited variations
between detectors to 0.2%. Removal of six Am-C radioactive
calibration sources reduced the background by a factor of two for the detectors
in the experimental hall furthest from the reactors. Direct prediction of the
antineutrino signal in the far detectors based on the measurements in the near
detectors explicitly minimized the dependence of the measurement on models of
reactor antineutrino emission. The uncertainties in our estimates of
and were halved as a result of these
improvements. Analysis of the relative antineutrino rates and energy spectra
between detectors gave and eV in the three-neutrino
framework.Comment: Updated to match final published versio
Measurement of higher cumulants of net-charge multiplicity distributions in AuAu collisions at GeV
We report the measurement of cumulants () of the net-charge
distributions measured within pseudorapidity () in AuAu
collisions at GeV with the PHENIX experiment at the
Relativistic Heavy Ion Collider. The ratios of cumulants (e.g. ,
) of the net-charge distributions, which can be related to volume
independent susceptibility ratios, are studied as a function of centrality and
energy. These quantities are important to understand the quantum-chromodynamics
phase diagram and possible existence of a critical end point. The measured
values are very well described by expectation from negative binomial
distributions. We do not observe any nonmonotonic behavior in the ratios of the
cumulants as a function of collision energy. The measured values of and can be directly compared to lattice
quantum-chromodynamics calculations and thus allow extraction of both the
chemical freeze-out temperature and the baryon chemical potential at each
center-of-mass energy.Comment: 512 authors, 8 pages, 4 figures, 1 table. v2 is version accepted for
publication in Phys. Rev. C as a Rapid Communication. 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
Systematic study of charged-pion and kaon femtoscopy in AuAu collisions at =200 GeV
We present a systematic study of charged pion and kaon interferometry in
AuAu collisions at =200 GeV. The kaon mean source radii
are found to be larger than pion radii in the outward and longitudinal
directions for the same transverse mass; this difference increases for more
central collisions. The azimuthal-angle dependence of the radii was measured
with respect to the second-order event plane and similar oscillations of the
source radii were found for pions and kaons. Hydrodynamic models qualitatively
describe the similar oscillations of the mean source radii for pions and kaons,
but they do not fully describe the transverse-mass dependence of the
oscillations.Comment: 499 authors, 27 pages, 13 figures, and 11 tables. v2 is the version
accepted for publication in 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
Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV
The energy dependence of the single-transverse-spin asymmetry, A_N, and the
cross section for neutron production at very forward angles were measured in
the PHENIX experiment at RHIC for polarized p+p collisions at sqrt(s)=200 GeV.
The neutrons were observed in forward detectors covering an angular range of up
to 2.2 mrad. We report results for neutrons with momentum fraction of x_F=0.45
to 1.0. The energy dependence of the measured cross sections were consistent
with x_F scaling, compared to measurements by an ISR experiment which measured
neutron production in unpolarized p+p collisions at sqrt(s)=30.6--62.7 GeV. The
cross sections for large x_F neutron production for p+p collisions, as well as
those in e+p collisions measured at HERA, are described by a pion exchange
mechanism. The observed forward neutron asymmetries were large, reaching
A_N=-0.08+/-0.02 for x_F=0.8; the measured backward asymmetries, for negative
x_F, were consistent with zero. The observed asymmetry for forward neutron
production is discussed within the pion exchange framework, with interference
between the spin-flip amplitude due to the pion exchange and nonflip amplitudes
from all Reggeon exchanges. Within the pion exchange description, the measured
neutron asymmetry is sensitive to the contribution of other Reggeon exchanges
even for small amplitudes.Comment: 383 authors, 16 pages, 18 figures, 6 tables. Submitted to Phys. Rev.
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
Cross sections and double-helicity asymmetries of midrapidity inclusive charged hadrons in p+p collisions at sqrt(s)=62.4 GeV
Unpolarized cross sections and double-helicity asymmetries of
single-inclusive positive and negative charged hadrons at midrapidity from p+p
collisions at sqrt(s)=62.4 GeV are presented. The PHENIX measurements for 1.0 <
p_T < 4.5 GeV/c are consistent with perturbative QCD calculations at
next-to-leading order in the strong coupling constant, alpha_s. Resummed pQCD
calculations including terms with next-to-leading-log accuracy, yielding
reduced theoretical uncertainties, also agree with the data. The
double-helicity asymmetry, sensitive at leading order to the gluon polarization
in a momentum-fraction range of 0.05 ~< x_gluon ~< 0.2, is consistent with
recent global parameterizations disfavoring large gluon polarization.Comment: PHENIX Collaboration. 447 authors, 12 pages, 5 figures, 5 tables.
Submitted to Physical Review
Observation of direct-photon collective flow in sqrt(s_NN)=200 GeV Au+Au collisions
The second Fourier component v_2 of the azimuthal anisotropy with respect to
the reaction plane was measured for direct photons at midrapidity and
transverse momentum (p_T) of 1--13 GeV/c in Au+Au collisions at sqr(s_NN)=200
GeV. Previous measurements of this quantity for hadrons with p_T < 6 GeV/c
indicate that the medium behaves like a nearly perfect fluid, while for p_T > 6
GeV/c a reduced anisotropy is interpreted in terms of a path-length dependence
for parton energy loss. In this measurement with the PHENIX detector at the
Relativistic Heavy Ion Collider we find that for p_T > 4 GeV/c the anisotropy
for direct photons is consistent with zero, as expected if the dominant source
of direct photons is initial hard scattering. However, in the p_T < 4 GeV/c
region dominated by thermal photons, we find a substantial direct photon v_2
comparable to that of hadrons, whereas model calculations for thermal photons
in this kinematic region significantly underpredict the observed v_2.Comment: 384 authors, 6 pages, 3 figures, and 1 table. Submitted to Phys. Rev.
Lett. v2 has minor changes to match the submission version. Plain text data
tables for the points plotted in the figures are publicly available at
http://www.phenix.bnl.gov/phenix/WWW/info/data/ppg126_data.htm
Azimuthal anisotropy of pi^0 and eta mesons in Au+Au collisions at sqrt(s_NN)=200 GeV
The azimuthal anisotropy coefficients v_2 and v_4 of pi^0 and eta mesons are
measured in Au+Au collisions at sqrt(s_NN)=200 GeV, as a function of transverse
momentum p_T (1-14 GeV/c) and centrality. The extracted v_2 coefficients are
found to be consistent between the two meson species over the measured p_T
range. The ratio of v_4/v_2^2 for pi^0 mesons is found to be independent of p_T
for 1-9 GeV/c, implying a lack of sensitivity of the ratio to the change of
underlying physics with p_T. Furthermore, the ratio of v_4/v_2^2 is
systematically larger in central collisions, which may reflect the combined
effects of fluctuations in the initial collision geometry and finite viscosity
in the evolving medium.Comment: 384 authors, 71 institutions, 11 pages, 9 figures, and 2 tables.
Submitted to Physical Review 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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