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DPG Spring Meeting 2011, Münster (Germany) 1 Photons and Jets from the first year of ALICE A. Marin, for the ALICE Collaboration Photons.

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Presentation on theme: "DPG Spring Meeting 2011, Münster (Germany) 1 Photons and Jets from the first year of ALICE A. Marin, for the ALICE Collaboration Photons."— Presentation transcript:

1 DPG Spring Meeting 2011, Münster (Germany) 1 Photons and Jets from the first year of ALICE A. Marin, for the ALICE Collaboration Photons and Jets from the first year of ALICE A. Marin, for the ALICE Collaboration

2 DPG Spring meeting 2011, Münster (Germany) 2 Outline The ALICE experiment The 2010 data sample Physics results in pp Photon physics Jets First results in PbPb

3 DPG Spring meeting 2011, Münster (Germany) 3 3 Size: 16 x 26 meters Weight: 10,000 tons Detectors: 18 ALICE:The dedicated HI Experiment

4 DPG Spring meeting 2011, Münster (Germany) 4 ALICE Status Complete: ITS, TPC, TOF, HMPID, FMD, T0, V0, ZDC, Muon arm, Acorde PMD, DAQ Partial installation: PHOS(3/5) 7/18 TRD 2-4/6 EMCAL ~ 50% HLT ALICE Detector Installation P. Kuijer

5 DPG Spring meeting 2011, Münster (Germany) 5 The 2010 data sample >800M MB, >100M triggers, >25M high multiplicity ~30M nuclear collisions

6 DPG Spring meeting 2011, Münster (Germany) 6 LHC: Entering a new regime LHC: Entering a new regime Cross-sections of interesting probes expected to increase by factors ~ 10 ( cc ) to ~ 10 2 ( b b ) to ~ > 10 5 (very high p T jets) ; Hard probes of the medium accessible at LHC Direct photons are abundantly produced at LHC C W Fabjan 2008 J. Phys. G: Nucl. Part. Phys. 35,

7 DPG Spring meeting 2011, Münster (Germany) 7 Photon physics in ALICE Measurement of 0 and mesons in and Highest energy available in lab Test of pQCD cross section predictions Reference data for PbPb Main source of background in direct photon/heavy flavour electron measurement Measurement of Direct photons (not from decays) in and Highest energy available in lab Test of pQCD cross section predictions Reference data for PbPb PbPb: hard processes in QGP medium, thermal properties of early phase -Jet ( -hadron) Study quark energy loss in the medium Fragmentation function: E jet ~ E (HK 22.2, HK 22.3)

8 DPG Spring meeting 2011, Münster (Germany) 8 0 and reconstruction 0 and reconstruction e+e+ e-e- Y X pp 0 + X n e + e - e + e - (m 0 = GeV/c 2, BR = 0.988) pp + X n e + e - e + e - (m = GeV/c 2, BR = 0.393) run , event independent measurements: Conversions, PHOS, EMCAL

9 DPG Spring meeting 2011, Münster (Germany) 9 V 0 : Secondary vertex reconstruction Reconstruction of ( K 0 S, ) converted photons in material (Z) Z e + e - Z F or analysis: Package for fitting decay particles based on the Kalman Filter Specific energy loss in the TPC Strict cut for material studies -3 dE/dx 1GeV, dE/dx > dE/dx( ) m( )=0 constrain to vertex 2 ( ) < 30

10 DPG Spring meeting 2011, Münster (Germany) 10 Photons from pair conversions: -ray image of ALICE ALICE material budget (11.4% X 0 ) agrees within +3.4,-6% with its implementation in GEANT simulations converted photons in material (Z): Z e + e - Z

11 DPG Spring meeting 2011, Münster (Germany) 11 0 and 7TeV 0 and 7TeV 0

12 DPG Spring meeting 2011, Münster (Germany) 12 Data 7 TeV: 0 invariant mass in p t bins Combinatorial bck using mixed events M GeV/c 2 for normalization Very low p t reached with the conversion method

13 DPG Spring meeting 2011, Münster (Germany) 13 Data 7TeV invariant mass in p t bins M GeV/c 2 for normalization

14 DPG Spring meeting 2011, Münster (Germany) 14 Raw yields. Reconstruction efficiency With 9.5 x 10 7 Minimum Bias collisions: 0 measured in 0.4 GeV/c < pt < 7GeV/c measured in 0.6 GeV/c < pt< 6 GeV/c

15 DPG Spring meeting 2011, Münster (Germany) 15 Differential 0 invariant yield Differential 0 invariant yield measured in pp TeV

16 DPG Spring meeting 2011, Münster (Germany) 16 Comparsion to NLO NLO predictions from W. Vogelsang Method and calculations described in: [1] F. Aversa et al., Nucl. Phys. B327, 105 (1989). [2] B. Jäger et al., Phys. Rev. D67, (2003). [3] D. de Florian, Phys. Rev. D67, (2003). pp =70mb used New ALICE measurement pp = 62.3±0.4(stat) ±4.3(syst.) mb

17 DPG Spring meeting 2011, Münster (Germany) 17 / 0 ratio / 0 ratio The / 0 ratio is measured in pp for 0.6 GeV/c


18 DPG Spring meeting 2011, Münster (Germany) 18 Direct photons at RHIC PHENIX Coll.:Phys. Rev. Lett. 94, (2005)PHENIX Coll.:Phys. Rev. Lett. 104 (2010) Excess exponential in p T T=221± 23(stat)±18(sys) MeV pp consistent with NLO pQCD calculations AuAu larger than calculation for p T <3.5GeV/c

19 DPG Spring meeting 2011, Münster (Germany) 19 How many direct LHC? Measurement was done at RHIC... but more difficult at LHC 0 = 0,01-0,1 for p T > 20 GeV/c We need a good distinction direct/decay Cern Yellow Report , hep-ph/

20 DPG Spring meeting 2011, Münster (Germany) 20 Photon decay cocktail Work in progress

21 DPG Spring meeting 2011, Münster (Germany) 21 Jets HK 22.4, HK 22.5, HK 22.6, HK 22.7, HK 40.9

22 DPG Spring meeting 2011, Münster (Germany) 22 Jet properties from di-hadron correlations 'away' side 'near'side UE Trigger particle Near side (intra-jet): Single jet properties, fragmentation Away side (inter-jet): Di-jet, hard scattering, properties, K T effects

23 DPG Spring meeting 2011, Münster (Germany) 23 Correlation functions:s= 0.9 and 7 TeV Large statistics allows up to 30 GeV/c of the trigger particle

24 DPG Spring meeting 2011, Münster (Germany) 24 Jet properties from di-hadron correlations Measure of average transverse momentum of fragmentation products relative to jet axis All measurements agree within the errors Expected independence on trigger particle p T and s confirmed

25 DPG Spring meeting 2011, Münster (Germany) 25 Away side width and k T z t ˆ x h k T 2 1 x h p out 2 j Ty 2 (1 x h 2 ) partonic hadronic/measured ALICE preliminary ALICE preliminary Confirmed expected increase of momentum imbalance of parton pair ( /2)x

26 DPG Spring meeting 2011, Münster (Germany) 26 Full Jet reconstruction in ALICE in 2010 Using central tracking detectors Charged jet reconstruction only Different jet finders UA1 cone algorithm FASJET Suite (k T, anti-k T, SIScone) Cone size 0.4 Comparison to PbPb Maximum efficiency of central barrel | jet |<0.5 Jet finding in PbPb Low momentum cut off (150 MeV)

27 DPG Spring meeting 2011, Münster (Germany) 27 Raw Jet Spectrum: Jet spectrum with charged particles safely reconstructed out to 70 GeV Jets | |<0.5 Tracks | |<0.8

28 DPG Spring meeting 2011, Münster (Germany) 28 First PbPb collisions in ALICE 0-5% cent: dN ch /d ~ 1584 ± 4 (stat) ± 76 (syst)

29 DPG Spring meeting 2011, Münster (Germany) 29 "Jet quenching" from charged particle spectra Suppression of high pt particles ( ~ leading jet fragments) Rising with pt ! Accuracy limited by pp reference => need pp at 2.76 TeV ! ALICE, Phys. Lett. B 696 (2011) 30 HK22.1

30 DPG Spring meeting 2011, Münster (Germany) 30 ATeV: 0 invariant mass in p t bins 0 can be reconstructed from 0.4 GeV/c to 12 GeV/c

31 DPG Spring meeting 2011, Münster (Germany) 31 0 raw yield vs p t 0 raw yield vs p t First step towards 0 R AA

32 DPG Spring meeting 2011, Münster (Germany) 32 Jet quenching from High p T correlations Away side correlation in central Pb-Pb washed out up to p T,trig >10GeV Clear away side correlation in

33 DPG Spring meeting 2011, Münster (Germany) 33 Raw anti-k T Jet Spectrum in Pb+Pb Event-by-event background subtracted,not unfolded. Effect of background fluctuations/smearing apparent. Detailed correction currently prepared.

34 DPG Spring meeting 2011, Münster (Germany) 34 Conclusions and outlook ALICE took data succesfully during the 2010 run for pp and PbPb collisions 0 (and ) mesons differential yields measured in pp collisions at 7 TeV. Basic ingredients for a direct photon measurement Jet properties measured in pp collisions from di-hadron correlations Full jet reconstruction is done using different algorithms. Work is still ongoing to apply all corrections High pt suppresion of charged particles is observed in central PbPb collisions. Jet quenching at LHC Uncorrected 0 p t spectrum and jet p t spectrum have been shown. Work is ongoing to obtain R AA ( 0 ) and fully corrected jet pt spectrum

35 DPG Spring meeting 2011, Münster (Germany) 35 ALICE TALKS PV 5.1ALICE in Wonderland: first results from the ALICE experiment at the LHC Peter Braun-Munzinger HK 7.8Online Drift Velocity Calibration with the Laser System of the ALICE-TPC Mesut Arslandok HK 12.9Central diffractive meson production in p+p collisions at s=7 TeV at the ALICE experiment Xianguo Lu HK 14.8The SysMES Inventory Module in the ALICE HLT Cluster Jochen Ulrich, Camilo Lara, Stefan Böttger, Timo Breitner, Pierre Zelnicek, and Udo Kebschull HK 14.9Virtual Machine Scheduling in the ALICE HLT Stefan Boettger, Jochen Ulrich, Camilo Lara, Timo Breitner, Pierre Zelnicek, and Udo Kebschull HK 15.3Korrelationen von schweren Quarkteilchen in hochenergetischen Kern-Kern-Reaktionen Andre Mischke HK 15.4Performance Studies for the Measurement of ψ via the Decay Channel ψ J/ψ π+π e+e π+π with the ALICE Detector Moritz Pohl, Christoph Blume, and Frederick Kramer HK 15.6Messung von Dielektronen niedriger Masse mit dem ALICE Detektor in Proton-Proton und Blei-Blei Kollisionen Markus Konrad Köhler HK 20.5A Common Read-Out Receiver Card for ALICE DAQ and HLT Heiko Engel and Udo Kebschull HK 22.1Suppression of Charged Particle Production at Large Transverse Momentum in Central PbPb Collisions at sNN=2.76 TeV Jacek Otwinowski HK 22.2Rekonstruktion von π0 und η Mesonen mittels Photon Konversionen in ALICE in Proton Proton Kollisionen am CERN LHC Friederike Bock HK 22.3Rekonstruktion von π0-Mesonen mittels Photon-Konversionen mit ALICE in PbPb-Kollisionen am CERN LHC Radoslav Rusanov

36 DPG Spring meeting 2011, Münster (Germany) 36 ALICE TALKS HK 22.4Jet and High-pT Measurments with the ALICE Experiment at the LHC Bastian Bathen, Tom Dietel, and Christian Klein-Bösing HK 22.5Quark and gluon composition of jets in proton-proton collisions at s = 7 TeV with ALICE at the LHC Hermes Leon Vargas HK 22.6Two- and Three-Particle Jet-Like Correlations in the ALICE Experiment at the LHC Jason Glyndwr Ulery HK 22.7Charged Particle Momentum Distribution in Jets in ALICE Bastian Bathen, Oliver Busch, and Christian Klein-Bösing HK 22.8ALICE TRD GTU Online Tracking and Trigger Performance in pp and PbPb Collisions Felix Rettig, Stefan Kirsch, and Volker Lindenstruth HK 22.9Beauty and beauty-jet measurement via displaced vertices with ALICE in p+p collisions at s = 7 TeV MinJung Kweon HK 28.1Alice HLT TPC Tracking of PbPb-Events on GPU and CPU David Rohr and Sergey Gorbunov HK 28.2Development of a trigger system to test and calibrate ALICE-TRD super-modules Jonas Anielski HK 39.20Ein Driftgeschwindigkeitsmonitor für den ALICE TRD Friederike Poppenborg HK 39.57ALICE Grid Computing at the GridKa Tier-1 center Christopher Jung and Kilian Schwarz HK 40.1Measurement of transverse momentum spectra of identified hadrons from pp and PbPb collisions with the ALICE experiment Alexander Kalweit HK 40.2Neutral strange hadron reconstruction in pp and PbPb collisions at LHC energies Simone Schuchmann

37 DPG Spring meeting 2011, Münster (Germany) 37 ALICE TALKS HK 40.3Measurement of nuclei and antinuclei with the ALICE experiment at the LHC Nicole Martin and Alexander Kalweit HK 40.5Event-by-event fluctuations of mean transverse momentum in pp collisions at s = 900 GeV and 7 TeV measured by the ALICE experiment Stefan Heckel HK 40.6Analyse der Pionenquelle durch HBT-Interferometrie mit ALICE Johanna Gramling HK 40.7Analyse von Pseudorapiditäts-Dichtekorrelationen mittels Multiplizitätsverteilungen in pp- und PbPb-Kollisionen mit ALICE Maren Hellwig HK 40.8Mini-Jet Activity as Function of Charged Multiplicity Eva Sicking HK 40.9Underlying Event measurement in pp collisions with the ALICE detector Sara Vallero for the ALICE collaboration HK 40.10Results of the Quality Assurance for the High Level Trigger Applications for the ALICE TRD Theodor Rascanu HK 61.1vom ALICE Tier2 zum FAIR Tier0 - Computing at GSI Kilian Schwarz HK 63.2Photons and Jets from the First Year of ALICE Ana Marin HK 64.1Measurement of the J/ψ Production Cross Section in pp Collisions at s=7 TeV with ALICE at the LHC and Perspectives for PbPb Collisions Frederick Kramer, Ionut Arsene, Christoph Blume, Julian Book, Anton Andronic, WooJin J. Park, and Jens Wiechula HK 64.2Electrons from heavy flavour decays with the ALICE experiment in proton-proton collisions at s= 7TeV Raphaelle Bailhache HK 64.3Messung des Wirkungsquerschnitts von Hadronen mit schweren Quarks in Proton-Proton Kollisionen mit dem ALICE Experiment Fasel Markus

38 DPG Spring meeting 2011, Münster (Germany) 38 ALICE TALKS HK 64.4Messung der Produktion schwerer Quarks in Pb+Pb Kollisionen mit dem ALICE Detektorsystem Yvonne Pachmayer HK 64.5Reconstruction of open charm in the decay channel D0 Kπ+ with ALICE Robert Grajcarek HK 64.6Open charm production in the D*+ D0 π+ decay channel with ALICE Yifei Wang

39 DPG Spring meeting 2011, Münster (Germany) 39 ALICE COLLABORATION 39

40 DPG Spring meeting 2011, Münster (Germany) 40 Backup slides

41 DPG Spring meeting 2011, Münster (Germany) 41 Differential invariant cross section PHOS + Conversions

42 DPG Spring meeting 2011, Münster (Germany) 42 Background density Strong change within one centrality bin. Better correlation in multiplicity

43 DPG Spring meeting 2011, Münster (Germany) 43 Testing Background Fluctuations Embedding of single tracks: δ-probe for jet finding at random position Random Cones: Sum in circular area at random position (excluding the two leading jets)

44 DPG Spring meeting 2011, Münster (Germany) 44 Charged Jets Jet quenching jet E -> jet E (=E- E) + soft gluons ( E) 47 GeV 102 GeV 0-10% central 192 GeV 168 GeV 10-20% peripheral

45 DPG Spring meeting 2011, Münster (Germany) 45 Charged particle multiplicity density dN ch /d ~ 1584 ± 4 (stat) ± 76 (syst) somewhat on high side of expectations growth with s faster in AA than pp PRL 105, (2010)

46 DPG Spring meeting 2011, Münster (Germany) 46 Centrality dependence of Charged particle multiplicity density Centrality dependence of the multiplicity is found very similar at s NN =2.76 and s NN =0.2TeV. Scale different by a factor 2.1 PRL 106, (2011)

47 DPG Spring meeting 2011, Münster (Germany) 47 Un-triggered CF

48 DPG Spring meeting 2011, Münster (Germany) 48

49 DPG Spring meeting 2011, Münster (Germany) 49 Probing Hot QCD Matter with hard probes Hard Probes: highly penetrating observables (particles, radiation) used to explore properties of matter that cannot be viewed directly! High p T particles: 0,, direct Jets p+p collisions provide a baseline

50 DPG Spring meeting 2011, Münster (Germany) 50 Hard probes p+p: parton scattering fragmentation jet can be calculated in perturbative QCD collinear factorization A+A: partons traversing medium lose energy gluon radiation, elastic collisions energy loss different for g, light/heavy quarks (color factor, dead cone effect) X.-N. Wang, M. Gyulassy, Phys. Rev. Lett. 68 (1992) 1480 Goal: Use in-medium energy loss to measure medium properties leading particle a b c d hadrons Parton distribution functionMatrix elementFragmentation function measured in DIS initial state (saturation?) e + e - final state (energy loss?) pQCD

51 DPG Spring meeting 2011, Münster (Germany) 51 R AA for 0, and direct R AA for 0, and direct R AA ~=1 R AA 0, ~=0.2 The hadron spectra at RHIC from p+p, Au+Au and d+Au collisions establish existence of parton energy loss from strongly interacting, dense QCD matter in central Au-Au collisions = 4 – 13 GeV 2 / fm dN g /dy~ S. Bass et al. PRC79 (2009) ^ https://wiki.bnl.gov/TECHQM/index.php/Main_page Theory-Experiment Collaboration on Hot Quark Matter

52 DPG Spring meeting 2011, Münster (Germany) 52 If trigger and associated hadrons fragment independently: First approximation: arcsin(x)~x and because =2 : Two approximations follow: (1) ~1/ 2 (2) is taken from inclusive (rather than jet) spectrum j T systematics: formulae 52

53 DPG Spring meeting 2011, Münster (Germany) 53 Borghini,Wiedemann, hep-ph/ Why photon-tagged jets? Medium effects redistribute ( q L ) the parton energy, E jet, inside the hadron jet (multiplicity, j T ). If we measure E E jet ^ E jet. Redistribution can be best measured with the Fragmentation Function... If we know E jet. HI environment hinders precise reconstruction of E jet. Quenching increases low-p T particles Quenching reduces high-p T particles 1/N jet dN/d

54 DPG Spring meeting 2011, Münster (Germany) 54 Photon Detection in ALICE PHOS (100 0 x 0.24 in (PHOS/CentralBarrel=0.037) high resolution (energy and spatial) small coverage EMCAL larger coverage: 120 O x 1.4 in η (EMCAL/CentralBarrel=0.26) coarser spatial resolution than PHOS available in 2010 e + e - Z Conversions (Central Barrel) large coverage: 360 O x 1.8 (2.4) in (Conversion/CentralBarrel=0.08) low conversion probability : 8% (16%)

55 DPG Spring meeting 2011, Münster (Germany) 55 Interaction of photons with matter Photoelectric effect Compton scattering Pair production: E >1.02MeV Electromagnetic Calorimeters: The complete photon energy is deposited in the detector (electromagnetic shower) Photon measurement via pair conversions: Determine photon momentum and direction by measuring e + /e - from a single conversion in tracking detectors ALICE ( ITS+TPC+TRD)

56 DPG Spring meeting 2011, Münster (Germany) 56 Direct photon sources...in a large background from 0 and decays q qg γ q q g γ q q q q g g g γ γ qg Compton Scattering qq Annihilation Bremsstrahlung, fragmentation Thermal photons from QGP and hadron gas Photons from Jet re-interaction in the medium Why? Do not interact strongly. Carry information about the early state.

57 DPG Spring meeting 2011, Münster (Germany) 57 Photon Production: different sources Photons are abundantly produced at LHC Jet-photon conversion in the plasma dominates 8

20GeV at LHC Turbide, Gale, Jeon, and Moore PRC (2004)

58 DPG Spring meeting 2011, Münster (Germany) 58 Data 7 TeV: 0 invariant mass in p t bins Combinatorial bck using mixed events M GeV/c 2 for normalization Very low p t reached with the conversion method

59 DPG Spring meeting 2011, Münster (Germany) 59 Data 7TeV invariant mass in p t bins M GeV/c 2 for normalization

60 DPG Spring meeting 2011, Münster (Germany) 60 Raw yields. Reconstruction efficiency With 9.5 x 10 7 Minimum Bias collisions: 0 measured in 0.4 GeV/c < pt < 7GeV/c measured in 0.6 GeV/c < pt< 6 GeV/c

61 DPG Spring meeting 2011, Münster (Germany) 61 Differential 0 invariant yield Differential 0 invariant yield measured in pp TeV

62 DPG Spring meeting 2011, Münster (Germany) 62 / 0 ratio / 0 ratio The / 0 ratio is measured in pp for 0.6 GeV/c


63 DPG Spring meeting 2011, Münster (Germany) 63 ATeV: 0 invariant mass in p t bins 0 can be reconstructed from 0.4GeV/c to 12GeV/c

64 DPG Spring meeting 2011, Münster (Germany) 64 0 raw yield vs p t 0 raw yield vs p t First step towards 0 R AA


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