Federico Antinori (INFN Padova, Italy) on behalf of the ALICE Collaboration

Transcription

1 Federico Antinori (INFN Padova, Italy) on behalf of the ALICE Collaboration

2 ALICE run Detector performance First physics results A taste of other analyses in advanced stage Outlook / Conclusion 2

3 ITS, TPC, TOF, HMPID, MUON, V0, To, FMD, PMD, ZDC (100%) TRD (7/18) EMCAL (4/12) PHOS (3/5) at nominal T (-25 C) HLT (60%) 3

4 based on interaction trigger reading all detectors: SPD (min bias) or V0-A or V0-C at least one charged particle in 8 pseudorapidity units and single-muon trigger reading MUON, SPD, V0, FMD, ZDC : single muon, low-pt threshold, in the muon arm in coincidence with interaction trigger activated in coincidence with the BPTX beam pickups: bunch-crossing with bunches from both sides for control bunch-crossing with bunch from side A or C only for control bunch-crossing with no bunches a fraction of bunch-crossing trigger (no condition on trigger detectors) for control to measure relative fractions of single- and double-diffractive events HLT in Mode B (no event rejection) 4

5 2009 (0.9 and 2.36 TeV) ~10.3 µb (till 23/5) (0.9 and 7 TeV) ~ 2.2 nb -1 ~ 500 k min bias ~ 160 M min bias 5

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7 now calibrating for internal alignment non-linear effects due to E field distortions ( mm effects) p t resolution (from cosmics) e.g.: at 10 GeV/c ~ 7% (target value ~ 5%) see also: J. Alme et al. (ALICE TPC), arxiv: (subm. to NIM) 7

8 use conversions to study material budget e.g.: TPC inner field cage (~ 1% X 0 ) current description accurate to 5 15% target: ~ 1 % precision 8

9 SPD: initial alignment with cosmics see K. Aamodt et al. (ALICE), arxiv: (accepted by JINST) SPD: pp data (improvement on the sides) SSD: for now global alignment only Δx from ladder overlaps: σ ~ 25 µm SDD: alignment + drift velocity calib σ/ 2 ~ 18 µm ~ intrinsic resolution internal alignment from survey adequate 9

10 e.g.: shoulder in the impact parameter distribution data MC p T = GeV/c alignment with cosmics only due to residual misalignment on the sides data MC cosmics + pp ( = 0 and π) p T = GeV/c 10

11 Impact parameter to primary vertex with and without luminous region constraint 11

12 de/dx versus momentum: 12

13 time resolution already close to nominal σ TOF =σ/ 2 = 88 ps b 13

14 de/dx (SDD, SSD) vs momentum electrons visible! 14

15 TRD: 7 out of 18 supermodules installed installed supermodules aligned with tracks gain calibration with g e+e- K 0 s p+p- 15

16 PHOS 3 out 5 modules installed and working at operational temperature 25 C calibration in progress EMcal 4 out 12 modules installed calibration in progress 6 modules prepared for installation HMPID fully installed alignment and calibration in progress PMD 90% of channels operational Hits Distribution Preshower plane CPV plane p K p 16

17 fully installed alignment not finalized yet L0 trigger on p t > 0.5 GeV trigger track matching matching efficiency Federico Antinori - ALICE - INT 10-2A - Seattle May

18 arxiv: First proton--proton collisions at the LHC as observed with the ALICE detector: measurement of the charged particle pseudorapidity density at sqrt(s) = 900 GeV K Aamodt et al: EPJ C 65 (2010) 11 arxiv: Charged-particle multiplicity measurement in proton-proton collisions at sqrt(s) = 0.9 and 2.36 TeV with ALICE at LHC accepted by EPJ C arxiv: Charged-particle multiplicity measurement in proton-proton collisions at sqrt(s) = 7 TeV with ALICE at LHC accepted by EPJ C 18

19 dn ch /dη for η < 0.5 dn ch /dη vs η K. Aamodt et al. (ALICE), Eur. Phys. J C 65 (2010) 111 data collected 23 Nov, paper submitted 28 Nov 284 events (~ 3.7 authors per event) 19

20 TeV arxiv: Consistent with UA5 (only 900 GeV) Consistent with CMS (only NSD) does not include charged leptons ~1.5 % difference UA5: only stat. uncertainty shown 2.36 TeV arxiv:

21 TeV Pythia D6T and Perugia-0 match neither INEL, NSD or INEL>0 at any energy Pythia Atlas CSC and Phojet reasonably close with some deviations at 0.9 and 2.36 TeV Only Atlas CSC close at 7 TeV 0.9 TeV 7 TeV

22 arxiv: points at the same energy slightly shifted arxiv: Power law dependence fits well Significantly larger increase from 0.9 to 7 TeV than in MCs Increase in dn ch /dh in h < 1 for INEL > 0 arxiv: s ALICE (%) MCs (%) TeV 23.3 ± TeV 57.6 ±

23 h < 0.5 arxiv: Distributions in limited h-regions Consistent with UA5 Fits with one NBD work well in limited h-regions arxiv: Difference between INEL and NSD in low-multiplicity region 0.9 TeV 23

24 24 Fits with one NBD work also at 2.36 and 7 TeV 2.36 TeV 7 TeV arxiv: arxiv:

25 25 arxiv: Phojet provides a good description at 900 GeV fails at 2.36 and 7 TeV Pythia Atlas CSC fails at 0.9 TeV reasonably close at 2.36 and 7 TeV but deviations around Pythia D6T and Perugia-0 far from the distribution at all energies 0.9 TeV 2.36 TeV 2.36 TeV 7 TeV arxiv: Federico Antinori - ALICE - INT 10- arxiv: A - Seattle - 24 May 2010

26 Charged particle p T distribution Baryon-antibaryon asymmetry Bose-Einstein correlations Strangeness production (K 0, Λ, Ξ, Φ) Identified particles p T (π, K, p) 26

27 Tsallis fit vs generators 27

28 vs generators 28

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30 Hambury Brown Twiss correlation for identical bosons (π - ) full analysis ready, under internal approval vs charged particle multiplicity and K T 30

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33 decay angle v mother s p Red curve: upper lim. for K µ Blue curve: upper lim. for π µ ALICE Work in Progress 33

34 + - PDG: MeV 34

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36 J/ψ e + e - J/ψ µ + µ - 36

37 π 0, η c and b production J/ψ production high multiplicity jet correlations event shape underlying events reconstructed jets b-tagged jets and of course Pb-Pb!... but John will tell you about that. 37

38 38 FA - Visita stude nti - 21 The fun has just started!!!