481 research outputs found

    Direct photon interferometry

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    We consider recent developments in the theory of the two-photon interferometry in ultrarelativistic heavy ion collisions with emphasis on the difference between photon and hadron interferometry. We review the available experimental results and discuss possibilities of measurement of the photon Bose-Einstein correlations in ongoing and future experiments.Comment: 6 pages, prepared for the Proceedings of Workshop on Particle Correlations and Femtoscopy (WPCF), Kromeriz, Czech Republic, August 15-17, 2005. Ref. adde

    Photon Physics in ALICE

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    We give an overview of photon physics which will be studied by the ALICE experiment in proton-proton and heavy ion collisions at LHC. We compare properties of ALICE photon detectors and estimate their ability to measure neutral meson and direct photon spectra as well as gamma-hadron and gamma-jet correlations in pp and Pb+Pb collisions.Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

    Direct photons at low pTp_{T} measured in PHENIX

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    Direct photon spectra measured at small pTp_T in p+p, d+Au and Au+Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were applied and found to produce consistent results. The p+p and d+Au results are found to be in very good agreement with pQCD predictions over the entire pTp_T range. No excess of direct photons in Au+Au collisions with respect to binary scaled d+Au data is observed within systematic errors.Comment: 4 pages, 3 figures, proceedings for Quark Matter 200

    Photon emission in Pb+Pb collisions at SpS and LHC

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    Yield of direct photons in Pb+Pb collisions at SpS and LHC energy is evaluated with emphasis on estimate of possible uncertainty. Possibility of experimental observation of direct photons at LHC is discussed. Predictions of several models at SpS energy are compared with experimental data.Comment: 19 pages, 13 figure

    Bose-Einstein correlations of direct photons in Au+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV

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    The current status of the analysis of direct photon Bose-Einstein correlations in Au+Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV done by the PHENIX collaboration is summarized. All possible sources of distortion of the two-photon correlation function are discussed and methods to control them in the PHENIX experiment are presented.Comment: 6 pages, 3 figures, Proceedings of Poster Session, 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2006), November 14-20, 2006, Shanghai, P.R.Chin

    Interferometry of direct photons in Pb+Pb collisions at 158 AGeV

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    We present final results from the WA98 experiment which provide first measurements of Bose-Einstein correlations of direct photons in ultrarelativistic heavy ion collisions. Invariant interferometric radii were extracted in the range 100<KT<300100<K_T<300 MeV/c and compared to interferometric radii of charged pions. The yield of direct photons for 100<pT<300100<p_T<300 MeV/c was extracted from the correlation strength parameter and compared to the yield of direct photons measured in WA98 at higher pTp_T with the statistical subtraction method, and to predictions of a fireball model.Comment: 4 pages, 3 figures, proceedings for Quark Matter 200
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