53 research outputs found
Direct Photon Production in Au+Au Collisions at RHIC-PHENIX Experiment
Direct photons have been measured with the PHENIX experiment in Au+Au
collisions at = 200 GeV. The direct photon result
obtained with PHENIX-EMCal up to 18 GeV/ is consistent with the NLO pQCD
calculation scaled by the nuclear overlap function. The measurement using
internal conversion of photons into shows the enhancement of the yield
comparing with NLO pQCD calculation.Comment: 4 pages, 5 figures. Contributed parallel talk at Hard Probes 2006,
Asilomar CA USA, Jun. 9-16, 200
Jet quenching and direct photon production
Jet quenching effect has been investigated in the direct photon production,
based on a realistic data-constrained (3+1) dimensional hydrodynamic
description of the expanding hot and dense matter, a reasonable treatment of
the propagation of partons and their energy loss in the fluid, and a systematic
study of the main sources of direct photons. Our resultant \pt spectra agree
with recent PHENIX data in a broad \pt range. Parton energy loss in the
plasma eventually effect significantly direct photon production from
fragmentation and jet photon conversion, similar to hadron suppression in
central heavy ion collisions. But this only causes about 40% decrease in the
total production of direct photons, due to the mixture with other direct photon
sources.Comment: 6 pages and 3 figures, To appear in the proceedings of the
International Conference on Strangeness in Quark matter (SQM2008), Beijing,
China, Oct 6-10, 200
Absolute Energy Measurements with Superconducting Transition-Edge Sensors for Muonic X-ray Spectroscopy at 44 keV
Superconducting transition-edge sensor (TES) microcalorimeters have great
utility in x-ray applications owing to their high energy resolution, good
collecting efficiency and the feasibility of being multiplexed into large
arrays. In this work, we develop hard x-ray TESs to measure the absolute
energies of muonic-argon (-Ar) transition lines around 44 keV and 20 keV.
TESs with sidecar absorbers of different heat capacities were fabricated and
characterized for their energy resolution and calibration uncertainty. We
achieved ~ 1 eV absolute energy measurement accuracy at 44 keV, and < 12 eV
energy resolution at 17.5 keV
Isomers in 128Pd and 126Pd: Evidence for a robust shell closure at the neutron magic number 82 in exotic palladium isotopes
Coulomb breakup reactions of 93,94 Zr in inverse kinematics
Coulomb breakup reactions of 93,94 Zr have been studied in inverse kinematics at incident beam energies of about 200 MeV/nucleon in order to evaluate neutron capture reaction methods. The 93 Zr(n,γ) 94 Zr reaction is particularly important as a candidate nuclear transmutation reaction for the long-lived fission product 93 Zr in nuclear power plants. One- and two-neutron removal cross sections on Pb and C targets were measured to deduce the inclusive Coulomb breakup cross sections, 375 ± 29 (stat.) ± 30 (syst.) and 403 ± 26 (stat.) ± 31 (syst.) mb for 93 Zr and 94 Zr, respectively. The results are compared with estimates using the standard Lorentzian model and microscopic calculations. The results reveal a possible contribution of the pygmy dipole resonance or giant quadrupole resonance in the Coulomb breakup reactions of 94 Zr
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