267 research outputs found
Development of acceptance criteria for batches of silane primer for external tank thermal protection system bonding applications
Concluding tests for the thermogravimetric and FTIR analyses of DC 1200 silane primers are discussed as well as methods for HPLC and GC analyses and for determining titanium and silicon by atomic absorption spectroscopy. Tables summarizes results obtained for residue, ash, titanium, silicone, Si/Ti ratio, OH-absorption, the lap-shear test, and the GC headspace for alcohols
Development of acceptance criteria for batches of silane primer for external tank thermal protection system bonding applications
Fourier transform infrared spectroscopy is currently the best technique for observing hydrolytic changes in DC 1200 silane the primers caused by moisture in the atmosphere. To further prove that FTIR can be used as a criterion test for acceptance of silane primer lots, intensities of the FTIR OH- band are being compared with primer adhesive bond strength using a mechanical test suggested by NASA. Results of tests for shear strength and Oh-absorption are tabulated and compared with FTIR absorption intensities in the OH-region
Development of acceptance criteria for batches of silane primer for external tank thermal protection system bonding applications
Silane primers for use as thermal protection on external tanks were subjected to various analytic techniques to determine the most effective testing method for silane lot evaluation. The analytic methods included high performance liquid chromatography, gas chromatography, thermogravimetry (TGA), and fourier transform infrared spectroscopy (FTIR). It is suggested that FTIR be used as the method for silane lot evaluation. Chromatograms, TGA profiles, bar graphs showing IR absorbances, and FTIR spectra are presented
Einstein metrics in projective geometry
It is well known that pseudo-Riemannian metrics in the projective class of a
given torsion free affine connection can be obtained from (and are equivalent
to) the solutions of a certain overdetermined projectively invariant
differential equation. This equation is a special case of a so-called first BGG
equation. The general theory of such equations singles out a subclass of
so-called normal solutions. We prove that non-degerate normal solutions are
equivalent to pseudo-Riemannian Einstein metrics in the projective class and
observe that this connects to natural projective extensions of the Einstein
condition.Comment: 10 pages. Adapted to published version. In addition corrected a minor
sign erro
Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter
Azimuthal angle \Delta\phi correlations are presented for charged hadrons
from dijets for 0.4 < p_T < 10 GeV/c in Au+Au collisions at sqrt(s_NN) = 200
GeV. With increasing p_T, the away-side distribution evolves from a broad to a
concave shape, then to a convex shape. Comparisons to p+p data suggest that the
away-side can be divided into a partially suppressed "head" region centered at
Delta\phi ~ \pi, and an enhanced "shoulder" region centered at Delta\phi ~ \pi
+/- 1.1. The p_T spectrum for the "head" region softens toward central
collisions, consistent with the onset of jet quenching. The spectral slope for
the "shoulder" region is independent of centrality and trigger p_T, which
offers constraints on energy transport mechanisms and suggests that the
"shoulder" region contains the medium response to energetic jets.Comment: 420 authors from 58 institutions, 6 pages, 4 figures. Submitted to
Physical Review Letters. 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
System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV
We present azimuthal angle correlations of intermediate transverse momentum
(1-4 GeV/c) hadrons from {dijets} in Cu+Cu and Au+Au collisions at sqrt(s_NN) =
62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is
broadened, non-Gaussian, and peaked away from \Delta\phi=\pi in central and
semi-central collisions in all the systems. The broadening and peak location
are found to depend upon the number of participants in the collision, but not
on the collision energy or beam nuclei. These results are consistent with sound
or shock wave models, but pose challenges to Cherenkov gluon radiation models.Comment: 464 authors from 60 institutions, 6 pages, 3 figures, 2 tables.
Submitted to Physical Review Letters. 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
Cold Nuclear Matter Effects on J/Psi as Constrained by Deuteron-Gold Measurements at sqrt(s_NN) = 200 GeV
We present a new analysis of J/psi production yields in deuteron-gold
collisions at sqrt(s_NN) = 200 GeV using data taken by the PHENIX experiment in
2003 and previously published in [S.S. Adler et al., Phys. Rev. Lett 96, 012304
(2006)]. The high statistics proton-proton J/psi data taken in 2005 is used to
improve the baseline measurement and thus construct updated cold nuclear matter
modification factors R_dAu. A suppression of J/psi in cold nuclear matter is
observed as one goes forward in rapidity (in the deuteron-going direction),
corresponding to a region more sensitive to initial state low-x gluons in the
gold nucleus. The measured nuclear modification factors are compared to
theoretical calculations of nuclear shadowing to which a J/psi (or precursor)
break-up cross-section is added. Breakup cross sections of sigma_breakup =
2.8^[+1.7_-1.4] (2.2^[+1.6_-1.5]) mb are obtained by fitting these calculations
to the data using two different models of nuclear shadowing. These breakup
cross section values are consistent within large uncertainties with the 4.2 +/-
0.5 mb determined at lower collision energies. Projecting this range of cold
nuclear matter effects to copper-copper and gold-gold collisions reveals that
the current constraints are not sufficient to firmly quantify the additional
hot nuclear matter effect.Comment: 453 authors from 59 institutions, 15 pages, 13 figures, 5 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
Cold Nuclear Matter Effects on J/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV
We present measurements of J/psi yields in d+Au collisions at sqrt(s_NN) =
200 GeV recorded by the PHENIX experiment and compare with yields in p+p
collisions at the same energy per nucleon-nucleon collision. The measurements
cover a large kinematic range in J/psi rapidity (-2.2 < y < 2.4) with high
statistical precision and are compared with two theoretical models: one with
nuclear shadowing combined with final state breakup and one with coherent gluon
saturation effects. To remove model dependent systematic uncertainties we also
compare the data to a simple geometric model. We find that calculations where
the nuclear modification is linear or exponential in the density weighted
longitudinal thickness are difficult to reconcile with the forward rapidity
data.Comment: 449 authors from 66 institutions, 6 pages, 3 figures. Submitted to
Physical Review Letters. 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 double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
The PHENIX experiment presents results from the RHIC 2005 run with polarized
proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at
mid-rapidity. Unpolarized cross section results are given for transverse
momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both
lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by
an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double
helicity asymmetries A_LL are presented based on a factor of five improvement
in uncertainties as compared to previously published results, due to both an
improved beam polarization of 50%, and to higher integrated luminosity. These
measurements are sensitive to the gluon polarization in the proton, and exclude
maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid
Communications. 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
Recommended from our members
Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV
The momentum distribution of electrons from semi-leptonic decays of charm and
bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is
measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC)
over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of
electrons from bottom to that from charm is presented. The ratio is determined
using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It
is found that the yield of electrons from bottom becomes significant above 4
GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative
quantum chromodynamics (pQCD) calculation agrees with the data within the
theoretical and experimental uncertainties. The extracted total bottom
production cross section at this energy is \sigma_{b\b^bar}= 3.2
^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. 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
- …