Measurements of the differential production of electrons from open-heavy-flavor hadrons with charm- and bottom-quark content in p+p collisions at s=200 GeV are presented. The measurements proceed ...through displaced-vertex analyses of electron tracks from the semileptonic decay of charm and bottom hadrons using the PHENIX silicon-vertex detector. The relative contribution of electrons from bottom decays to inclusive heavy-flavor-electron production is found to be consistent with fixed-order-plus-next-to-leading-log perturbative-QCD calculations within experimental and theoretical uncertainties. These new measurements in p+p collisions provide a precision baseline for comparable forthcoming measurements in A+A collisions.
The PHENIX experiment has measured the spin alignment for inclusive J=ψ → e+e− decays in protonproton collisions at √s = 510 GeV at midrapidity. The angular distributions have been measured in three ...different polarization frames, and the three decay angular coefficients have been extracted in a full two-dimensional analysis. Previously, PHENIX saw large longitudinal net polarization at forward rapidity at the same collision energy. This analysis at midrapidity, complementary to the previous PHENIX results, sees no sizable polarization in the measured transverse momentum range of 0.0 < pT < 10.0 GeV=c. The results are consistent with a previous one-dimensional analysis at midrapidity at √s = 200 GeV. The transverse-momentum-dependent cross section for midrapidity J=ψ production has additionally been measured, and after comparison to world data, a simple logarithmic dependence of the cross section on √s was found.
The yield of direct photons in Pb + Pb collisions at SpS and LHC energies is evaluated with emphasis on estimates of possible uncertainties. The possibility of experimental observation of direct ...photons at LHC is discussed. Predictions of several models at SpS energy are compared.
Performance of the ALICE photon spectrometer PHOS Conesa, G.; Delagrange, H.; Díaz, J. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
01/2005, Volume:
537, Issue:
1-2
Journal Article, Conference Proceeding
Peer reviewed
We present in this paper the measured characteristics of a 64 lead–tungstate crystal array designed to detect high-energy photons and neutral mesons with the ALICE photon spectrometer PHOS. The array ...has been tested with electron and charged pion secondary beams delivered by the CERN PS and SPS synchrotrons. Photon energy and π0 invariant mass resolutions are presented. The PHOS particle identification performance for data simulated with the AliRoot package is studied.
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