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Status of Heavy Ion

Status of Heavy Ion. Sasha Milov. LHC run2010 with Pb+Pb. At the end of 2010 LHC took a very successful data with Pb+Pb @ √ s NN = 2.75 TeV Both LHC and ATLAS performances were beyond expectations. Chronologically Nov 2: end of p+p +2days: injecting Pb +2days: first collisions

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Status of Heavy Ion

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  1. Status of Heavy Ion Sasha Milov Sasha Milov ATLAS IL meeting Jan 03, 2011

  2. LHC run2010 with Pb+Pb At the end of 2010 LHC took a very successful data with Pb+Pb @ √sNN = 2.75 TeV Both LHC and ATLAS performances were beyond expectations. Chronologically Nov 2: end of p+p +2days: injecting Pb +2days: first collisions +2days: stable beams +2days: 4x4 bunches +2-3days 64x64bunches Nov 24: first PRL. 9.2ub-1 (7.7b cross section) Dec 24: J/psi & Z paper Sasha Milov ATLAS IL meeting Jan 03, 2011

  3. A HI event Sasha Milov ATLAS IL meeting Jan 03, 2011

  4. The HI event. Sasha Milov ATLAS IL meeting Jan 03, 2011

  5. A oicture needs to be expained Find a high-pT particle Look around it in p+p and find a jet Look at 180o and find its back-to-back partner The same in d+Au Find the near-side jet in A+A And no back-to-back partner Partners of the hard-scattered probes are absorbed in the media. Sasha Milov ATLAS IL meeting Jan 03, 2011

  6. Pictures which do not... Sasha Milov ATLAS IL meeting Jan 03, 2011

  7. The results p+p reference (open circles) the same in all plots. MC (yellow histogram) does not imply the media effects Small asymmetry di-jets reduce with centrality, large asymmetry di-jets increase with centrality. All jets peak at -π Possibly there is some broadening of the jets Sasha Milov ATLAS IL meeting Jan 03, 2011

  8. Multiplicity arXiv:1012.1657v1 ATLAS: analysis ongoing The most central bin well agrees With ALICE paper Better rapidity coverage Several independent methods arXiv:1011.3916v2 Sasha Milov ATLAS IL meeting Jan 03, 2011

  9. Multiplicity Use Pixel detector only: low occupancy, low pT cut, wide coverage. Method 1: Combine all hits and confirm B-layer hit with layer 1 hit. Method 2: Combine all hits then flip the detector and subtract the combinatorial Method 3: use standard pixel tracks with (in no field runs) Columbia U. Sasha Milov ATLAS IL meeting Jan 03, 2011

  10. Multiplicity Use Pixel detector only: low occupancy, low pT cut, wide coverage. Method 1: Combine all hits and confirm B-layer hit with layer 1 hit. Method 2: Combine all hits then flip the detector and subtract the combinatorial Method 3: use standard pixel tracks with (in no field runs) Sasha Milov ATLAS IL meeting Jan 03, 2011

  11. Flow Z Reaction plane Y X f Pz Py Px Nch yield The Fourier transform of azimuthal distribution There all odd coefficients especially important is v2 Known to be large at RHIC (scaled) Flow Krakow Multiplicity Sasha Milov ATLAS IL meeting Jan 03, 2011

  12. Flow 17 Nov: arXiv:1011.3914, acc. PRL STAR at RHIC Sasha Milov ATLAS IL meeting Jan 03, 2011 12

  13. Spectra. dNAA/dpT σpp<TAB> dNpp/dpT RAA= ~2008 -- 2010 Phys. Rev. Lett. 91, 072301 (2003) Sasha Milov ATLAS IL meeting Jan 03, 2011

  14. Spectra. ALICE 1012.1004v1 Approximately 20%of run statistics Central (0-10%) Peripheral (60-80)% Figure is 2 weeks old. There is lot more statistics BNL; WIS Sasha Milov ATLAS IL meeting Jan 03, 2011

  15. Data vs. MC (HIJING) Data and MC look different: Total number of tracks above pT=0.5 GeV is similar, but HIJING has lower pT (no flow). As a result the tracks with pT<0.5 produce more hits per track above the threshold Data MC Sasha Milov IDTCP meeting Dec 07, 2010

  16. Hit statistics in MinBias Per track hit statistics reflects the detector occupancy Pixel<SCT<TRT The effects are also consistent to what is expected from HIJING Sasha Milov IDTCP meeting Dec 07, 2010

  17. Hit statistics in  Data and MC look different: Total number of tracks above pT=0.5 GeV is similar, but HIJING has lower pT (no flow). As a result the tracks with pT<0.5 produce more hits per track above the threshold Sasha Milov IDTCP meeting Dec 07, 2010

  18. Hit statistics in centrality Sasha Milov IDTCP meeting Dec 07, 2010

  19. Vertex pointing in pT Selecting primary particles using the p+p cuts gives good results pT dependent Sasha Milov IDTCP meeting Dec 07, 2010

  20. Further optimization. Need to look at centrality and (may be) in charge. Sasha Milov IDTCP meeting Dec 07, 2010

  21. Further optimization. And in rapidity? Main questions: How to clean the secondaries? How far in pT can we go before being overwhelmed by feed-downs How to correct for efficiency? different cuts negpos Sasha Milov IDTCP meeting Dec 07, 2010

  22. Trigger and centrality WIS Sasha Milov ATLAS IL meeting Jan 03, 2011

  23. Trigger and centrality

  24. Two particle correlations SUNYSB (chem)

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