HeavyIonPhotons

Introduction

At this page you will find data on direct photons in Heavy Ion environment

Photon spectra

• The energy deposition in the strip layers around the direction of (upper left) a single photon, (upper middle) a single p0 and (upper right) a single eta as well as for (lower row) the identical particles embedded in a central (b = 2 fm) Pb+Pb event. The energy values are the reconstructed energies.

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• Fig. 8.3 from PPR: Distributions of shower-shape variables for single signal photons and for background clusters from single neutral mesons for the six variables listed in the text. The photons and mesons have |h| < 0.75 and 45 GeV< ET <70 GeV.

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• The isolation cuts. pdf

• Signal to background ratios
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• Direct photon spectra
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• Figure 8.4 from PPR: (left) Photon identification efficiency and (right) relative rejection factor for neutral hadrons for the loose cut set for single particles (open circles) and central (b = 2 fm, dNch/dh =2650) Pb+Pb collisions (filled triangles). These are averaged over the entire range |eta| < 2.4.

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• Figure 8.5 from PPR: (left) Photon identification efficiency and (right) relative rejection factor for neutral hadrons for the tight cut set for single particles (open circles) and central (b = 2 fm, dNch/dh = 2650) Pb+Pb collisions (filled triangles). These are averaged over the entire range |eta| < 2.4.

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• The photon efficiency and absolute rejection for background neutral hadrons for the isolation cuts (see Table. 8.1) as a function of energy in (left) p+p and (right) central Pb+Pb events.
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• Figure 8.6 from PPR: Angular resolution, (left) pseudo-rapidity and (right) azimuthal angle, vs. ET for single photons and single photons embedded in Pb+Pb HIJING events.

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• Figure 8.7 from PPR: Relative energy resolution vs. ET for reconstructed single photons and those embedded in Pb+Pb HIJING events.

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• Figure 8.10 from PPR: The performance of the shower shape cuts and isolation cuts on PYTHIA di-jets embedded into b = 2 fm Pb+Pb events. The spectra shown are for input jets (open circles), input p0 + h (solid square), remaining p0 + h (solid circles), expected direct g (solid line) and direct g

surviving all cuts (dashed line).
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• Figure 8.11 from PPR: The ratio of direct photons over background neutral hadrons passing the loose shower shape cuts only (solid squares), isolation cuts only (open circles) and combined cuts (solid circles) in central Pb+Pb events, assuming (left) no suppression for hadrons, and (right) a factor of 5 suppression for hadrons.

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• The ratio of direct photons over background neutral hadrons passing the loose shower shape cuts only (solid squares), isolation cuts only (open circles) and combined cuts (solid circles) for different occupancies under the assumption that the nuclear modification factor RAA = 1, for all centralities.

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gamma jet correlations

• Correlations in Dphi for g-jet pairs where both the photon and the jet have 40-60 GeV (left) and 60-80 GeV (right) in ET. Two different fake-jet-rejection cuts are used: tight (filled symbols) and loose (open symbols).

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• The resulting g-jet signal-to-background in the peak region for both sets of ET bins.

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Major updates:
-- AdamTrzupek - 07 Jul 2009

Responsible: AdamTrzupek
Last reviewed by: Never reviewed