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First ALICE photon papers

First ALICE photon papers. Yuri Kharlov PWG4 meeting on 24.08.2009. Titles of the first papers. The ALICE electromagnetic calorimeters (EMCAL+PHOS) can publish the following first physics results: Measurement of the inclusive  0 spectrum in midrapidity in pp collisions at s=7 TeV

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First ALICE photon papers

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  1. First ALICE photon papers Yuri Kharlov PWG4 meeting on 24.08.2009

  2. Titles of the first papers The ALICE electromagnetic calorimeters (EMCAL+PHOS) can publish the following first physics results: • Measurement of the inclusive 0spectrum in midrapidity in pp collisions at s=7 TeV • Measurement of the inclusive  spectrum in midrapidity in pp collisions at s=7 TeV • Measurement of the inclusive (782) spectrum in midrapidity in pp collisions at s=7 TeV • 0 production in pp collisions at s=7 TeV at high event multiplicity • Measurement of the total transverse energy in pp collisions at s=7 TeV Very likely that [1] and [2] will be combined into one paper. First ALICE photon papers

  3. Scope of the first papers • After the first 107 pp@7 TeV events PHOS and EMCAL will collect enough statistics to measure inclusive 0 spectra at pT<10 GeV/c • More accumulated statistics (108 pp events) will extend the measured spectra in PHOS and EMCAL up to pT<20 GeV/c • Even more accumulated statistics (>109 pp events) will extend the measured spectra in PHOS only up to pT<30-40 GeV/c • PHOS and EMCAL will measure other light neutral mesons,  and (782) till pT slightly lower than that for 0. • High charged track multiplicity can be triggered by SPD. The pT spectrum of 0 should change compared to inclusive spectrum: it is expected to reflect the thermalization in pp collisions. • Measurement of the photon transverse energy of neutral particles, as a rule, is the simplest analysis and provides the first tests of pQCD predictions. The total transverse energy could be obtained from the photon ET via unfolding. First ALICE photon papers

  4. Abstracts [1] The invariant cross section for inclusive 0 production has been measured in pp collisions at s=7 TeV at 1<pT<30 GeV/c by the ALICE experiment at LHC. The experimental result is compared with pQCD NLO predictions and sets the constraints on the proton structure functions and 0 fragmentation function. [2] The invariant cross section for inclusive  production and the ratio /0 have been measured in pp collisions at s=7 TeV at 1<pT<25 GeV/c by the ALICE experiment at LHC. The result is consistent with the pQCD predictions. [3] The (782) meson has been detected in the decay channels 0 and 0 by the ALICE experiment at LHC. The invariant cross section for inclusive  production and the ratio /0 have been measured in pp collisions at s=7 TeV at 3<pT<20 GeV/c The result is consistent with the pQCD predictions. [4] The semi-inclusive neutral meson production has been measured by the ALICE experiment in pp collisions at s=7 TeV at high event multiplicity. The pT spectrum is compared with that of inclusive production and the thermalization properties of high-multiplicity pp collisions are discussed. [5] The transverse energy spectrum of photons is measured in pp collisions at s=7 TeV over the range 5<ET<30 GeV. Reconstruction of the total ET is discussed. The experimental result is consistent with the pQCD predictions. First ALICE photon papers

  5. Detection rates in 3 PHOS modules Similar estimations are needed for 4 EMCAL modules: =40 <0.7, taking into account the EMCAL reconstruction efficiency (not ready yet). First ALICE photon papers

  6. Paper 1: List of Figures “Measurement of the inclusive 0spectrum in midrapidity in pp collisions at s=7 TeV” • Fig.1: Invariant mass spectrum of cluster pairs in PHOS and EMCAL in the range 0-300 MeV/c2 at pT ranges 1-2 GeV/c and 10-11 GeV/c. • Fig.2: Reconstruction and trigger efficiencies normalized per =2 and y<1 for 0vspT in PHOS and EMCAL • Fig.3: Invariant cross section for inclusive 0 production superposed by the pQCD NLO predictions; bands of systematic errors. First ALICE photon papers

  7. Paper 2: List of Figures “Measurement of the inclusive  spectrum in midrapidity in pp collisions at s=7 TeV” • Fig.1: Invariant mass spectrum of cluster pairs in PHOS and EMCAL in the range 200-700 MeV/c2 at pT ranges 2-3 GeV/c and 10-11 GeV/c. • Fig.2: Reconstruction and trigger efficiencies normalized per =2 and y<1 for vspT in PHOS and EMCAL • Fig.3: Invariant cross section for inclusive  production superposed by the pQCD LO predictions; bands of systematic errors. • Fig.4: Ratio of experimental invariant cross sections /0vspT superposed by the pQCD predictions. First ALICE photon papers

  8. Paper 3: List of Figures “Measurement of the inclusive (782) spectrum in midrapidity in pp collisions at s=7 TeV” • Fig.1: Invariant mass spectrum of 3 cluster in PHOS and EMCAL and that of 0 in PHOS+TPC and EMCAL+TPC in the range 500-1000 MeV/c2 at pT ranges 6-7 GeV/c. • Fig.2: Reconstruction and trigger efficiencies normalized per =2 and y<1 for 0 and 0vspT in PHOS and EMCAL • Fig.3: Invariant cross section for inclusive  production superposed by the pQCD LO predictions; bands of systematic errors. • Fig.4: Ratio of experimental invariant cross sections /0vspT superposed by the pQCD predictions. First ALICE photon papers

  9. Paper 4: List of Figures “0 production in pp collisions at s=7 TeV at high event multiplicity” • Fig.1: High-multiplicity trigger efficiency vs charged track multiplicity. • Fig.2: Invariant spectrum for 0 production as a function of pT and charged track multiplicity. First ALICE photon papers

  10. Paper 5: List of Figures “Measurement of the transverse energy of neutral particles in pp collisions at s=7 TeV” • Fig.1: The convolution spectra of ETvs sum of cell amplitudes and ETvs sum of cluster energies • Fig.2: The ET yield d/dET. The job is progress, Several people are interested. See http://indico.cern.ch/getFile.py/access?contribId=3&resId=0&materialId=slides&confId=47457 See ET presentation later at this PWG4 meeting. First ALICE photon papers

  11. Invariant mass spectra at different pT First ALICE photon papers

  12. 0,  and  efficiencies (acceptance) First ALICE photon papers

  13. Measured and theoretical invariant cross section pp0X ppX ppX First ALICE photon papers

  14. Layout of the papers 1, 2 and 3 • Introduction: • physics motivation, pQCD predictions, discussion on uncertainties in theoretical models. • Brief description of the ALICE setup. • Detailed description of the ALICE calorimeters PHOS and EMCAL: geometry, inner structure, amplitude measurement, FEE, DCS, DAQ. • Run conditions: beam energy, luminosity, diamond size, trigger • Analysis description: • Event selection (energy threshold, PID, energy asymmetry, bad channels), event characteristics • Calibration procedure: pre-calibration, on-line calibration, off-line calibration; show the accuracies of each calibration step. • invariant mass analysis, fitting of the mass spectra, combinatorial background subtraction (Fig.1). • Reconstruction efficiency: acceptance, trigger, correction for converted photons, correction for the smearing effect (Fig.2) • Reconstruction of the production invariant cross section (Fig.3a) • Systematic error from various sources: decalibration, PID, conversion, bad channels, boundary effects (Fig.3b) • Discussion and conclusion: comparison of the measured inclusive spectra with pQCD LO and NLO calculations First ALICE photon papers

  15. Additional text for the Paper 4 • Multiplicity measurement in ALICE with ITS: trigger on multiplicity, event selection • Dependence of the calorimeter event characteristics on the event multiplicity: cluster and cell multiplicity, cluster energy. • Dependence of the 0 spectrum on event multiplicity: comparison of slopes, 0 multiplicities. First ALICE photon papers

  16. Analysis readiness • Invariant mass spectrum of cluster pairs: basically ready, included to the Analysis Train, but needs extended functionality • Invariant mass spectrum of 3 clusters: the code is prepared, but is not in production; some technical errors are to be fixed • Reconstruction efficiency: basically ready, but a consolidated code is missing in aliroot. Special MC production is required but missing yet • Trigger efficiency: no progress • Luminosity measurements: to be provided by LHC and ALICE; common problem for any cross section measurement (who else in ALICE is going to measure cross section?) • Systematic errors: some sources of sys.errors were estimated, some others are still at the level of ideas First ALICE photon papers

  17. Organizational issues • Conveners: G.Conesa, Y.Kharlov, H.Torii • Contributors: L.Benhabib, D.Blau, F.Chuman, O.Djuvsland, A.Hiei, M.Huang, I.Ilkyv, T.Iwasaki, P.Kurashvili, Y.Mao, J.Mlynarz, D.Peressounko, B.Polishchuk, H.Qvigstad, K.Shigaki, R.Wan. • Joint working group with PHOS and EMCAL has been created. The new mailing list is opened: alice-calorimeter-analysis-forum@cern.ch First ALICE photon papers

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