Presentation is loading. Please wait.

Presentation is loading. Please wait.

First identified particle studies at the CERN-LHC with the ALICE experiment Panos Christakoglou a,b for the ALICE Collaboration 26.03.2010

Published byTyrone Phillips Modified over 9 years ago

Similar presentations

Presentation on theme: "First identified particle studies at the CERN-LHC with the ALICE experiment Panos Christakoglou a,b for the ALICE Collaboration 26.03.2010"— Presentation transcript:

1 First identified particle studies at the CERN-LHC with the ALICE experiment Panos Christakoglou a,b for the ALICE Collaboration 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 1 a NIKHEF b Utrecht University

2 Outline  The ALICE experiment at LHC o Experimental setup o PID design performance  Commissioning of the PID detectors o Results from the ITS o Results from the TPC o Results from the TOF  First physics measurements o Identified particle spectra o Baryon number transport  Conclusion 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 2

3 Experimental setup 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 3

4 PID in ALICE  PID for hadrons in the central barrel (|η| < 0.9) o ITS: Excellent (3σ) separation from ~50 MeV/c for π o TPC: π from 200 MeV/c, Κ from 300 MeV/c o TOF: K up to 2.5 GeV/c, p up to 3.5 GeV/c o HMPID: intermediate to high momenta  Photons with the dedicated spectrometer (PHOS)  Electrons in the central barrel: o ITS + TPC for low momentum o TRD from P ~ 1GeV/c (beauty measurements feasible even @1GeV/c!)  Muons reconstructed in the forward region (muon arm: -4 < η < -2.4) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 4 PID – momentum reach

5 ITS commissioning 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 5  Design goals o Optimal resolution for primary vertex and track impact parameter  Minimize distance of innermost layer from beam axis ( ≈ 3.9 cm) and material budget o Maximum occupancy (central PbPb) < few % o dE/dx information in the 4 outermost layers for particle ID in 1/β 2 region  Installed in 2007.  Successfully commissioned during the cosmics runs in 2008 and 2009. LayerDet. Type Radius (cm) Length (cm) Resolution (  m)PbPb dN/dy=6000 rr ZPart./cm 2 Occupancy (%) 1SPD3.928.212100352.1 2SPD7.628.212100120.6 3SDD15.044.4352532.5 4SDD23.959.435251.51.0 5SSD38.086.2208300.64.0 6SSD43.097.8208300.453.3

6 ITS alignment 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 6  First order alignment with cosmics using the SPD trigger o Coincidence between top outer SPD layer and bottom outer SPD layer (rate: 0.18 Hz)  Preliminary results show: o Space point resolution for the SPD of ~14 μm in rφ (matching between upper and lower part of a track). o Residual misalignment spread of the SSD modules on the ladders of ~5μm  Outlook: o Inclusion of the SDD o Alignment with magnetic field with beams (p t dependence). ALICE collaboration 2010 JINST 5 P03003

7 ITS calibration and PID (SDD + SSD) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 7  Charge distribution measured on all the SDD modules o ~95% of the detector included in the readout during data taking  Charge distribution measured on all the SSD modules o 90% of the detector active in 2009 o <1.5% bad strips o S/N ~40 dE/dx resolution ~ 13%

8  Main TPC characteristics o Cylindrical in shape, with an active volume that has an inner radius of about 85 cm, an outer radius of about 250 cm, and an overall length along the beam direction of 500 cm (largest TPC ever built) o Cylindrical field cage filled with ~90 m 3 of Ne/CO 2 /N 2 gas mixture (90:10:5) o Drift time of ~90 μs o Many (>90) 3D points (+dE/dx) per track  Since August 2009 more than 750 million events (cosmics, krypton, and laser) recorded, with and without B- field. o First round of calibrations (dE/dx, momentum, alignment, gain) completed before collisions. TPC commissioning 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 8

9 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 9 J. Alme et al. (ALICE TPC), arXiv:1001.1950 (subm. to NIM) TPC particle identification dE/dx resolution ~ 5% September 2009 December 2009

10 TOF 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 10  18 sectors, 2π covering in |η| < 0.9  Granularity: 2.5x3.5 cm2 at ∼ 3.7 m from the primary vertex;  Resolution at present ∼ 130 ps (calibration only from cosmic rays)

11 Analysis details 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 11 Event Selection Online TriggerYes Offline TriggerYes |V z |<1 0 |V x |<1 |V y |<1 Track Selection – Primary like cuts dca0.2 - 2.0 cm Track Selection – Quality cuts Number of TPC clusters80 Number of TPC clusters (dE/dx)80 x 2 /N TPCclusters 3.5 Number of ITS clusters2 Hit on SPD1 || SPD2Yes Analysis of the p+p events collected during the first LHC run in December Accepted events: 250K

12 Hadron spectra – π, Κ, p 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 12  Subtract measured signal (dE/dx or tof) from the expected one for each p t bin  Yields extracted from a fit with a convolution of three Gaussians  Compare results with a simple 3σ cut ITS TPC TOF

13 Hadron spectra - π, Κ, p (cont). 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 13  ITS points to be added: new reconstruction pass based on the latest calibration constants (SDD)  Excellent agreement between TPC and TOF in the overlap regions: max. difference of 6%

14 K ± from Kinks 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 14 π- kinks M. Spyropoulou-Stassinaki, P. Ganoti, A. Belogianni, F. Roukoutakis  Preliminary results in good agreement with the K ± spectra obtained from the dE/dx and TOF PID

15 Baryon number transport – Motivation 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 15  Who is the carrier of the baryon number? o Valence quarks: G.C. Rossi and G. Veneziano, Nucl. Phys B123 (1977) 507. o Gluonic field: B.Z. Kopeliovich and B. Zakharov, Z. Phys. C43 (1989) 241.  Different approaches based on theory: o QGSM considers the baryon as a bound quark-diquark state. BN transport implies breaking the diquark pair. o Gluonic mechanism aka String Junction (SJ). BN transport implies the stopping of the SJ. u u d u u d Conventional approach - QGSM Within QGSM one expects an asymmetry ~0 at LHC energies  No BN transported at mid-rapidity from the fragmentation region du u SJ String Junction BN transport even at large rapidity gaps (large energies).  Veneziano: Probability exponentially suppressed (a J : SJ intercept – model dependent)  Kopeliovich: Probability constant with rapidity LHC’s large rapidity gap between the incoming protons (y p = ±9.6) will give us the opportunity to distinguish between the different models.

16 Baryon number transport – Experimental results 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 16 BRAHMS: Phys. Lett. B607 (2005) 42 p+p - Au+Au @√s = 200GeV p+p Au+Au 20% central PYTHIA HIJING-B STAR: Phys.Rev.Lett.86 (2001) 4778 Lessons from RHIC A. Falkiewicz: DIS2008, London Lessons from HERA  Proton excess at mid- rapidity can be attributed to the BN transport from the beam at RHIC energies  No sign of any rapidity or p t dependence  PYTHIA systematically overestimates the proton ratio  HIJING-B describes the experimental data  Initially reported an asymmetry of ~8% for Δy ~ 7. o Results never published due to large systematic uncertainties caused by the high beam-gas rate.  Results reported at the DIS2008 are compatible with an asymmetry for Λs ~0

17 Baryon number transport – Corrections (I) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 17  Apply corrections that don’t cancel out in the ratio: o Absorption o Cross section in transport codes o Secondaries (mainly protons) Absorption  Extract corrections based on MC sample  Rely on the proper description of the material in the simulation  Rely on the interaction cross-section used in the transport code (GEANT3)

18 Baryon number transport – Corrections (II) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 18 Bendiscioli and Kharzeev, Riv.Nuovo Cim.17N6, 1-142 (1994) Detailed study published in 2008: ALICE-INT-2008-010.v1  Scaling factor for the absorption corrections defined as ε GEANT /ε FLUKA  ~2.5% decrease of the absorption correction

19 Baryon number transport – Corrections (III) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 19  Fit the dca distributions of primary antiprotons which are background free.  Use the same function and fit the primary protons scaled by the ratio (free parameter).  Fit the dca distributions of secondaries (protons coming from the interaction of particles with the material).  Use the same fitting functions to fit the dca distributions from real data.

20 Baryon number transport – Results (I) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 20 Fully corrected ratio: stat. error – lines, syst. error – shaded are around data points  Preliminary results show no sign of any rapidity or p t dependence.  Experimental points are compared with different model predictions that include variation of BN transport mechanisms: o HIJING-B clearly underestimates the y dependence, whereas it predicts a decrease of the ratio with increasing p t not seen in p+p collisions. o QGSM’s (only y information) version with a SJ ≠ 0 is systematically below the data points o The different PYTHIA tunes describe the data well.

21 Baryon number transport – Results (II) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 21  Mid-rapidity ratio for ALICE extracted by fitting the y dependence plot at |y| < 0.5.  Preliminary results show still a small excess of baryons over antibaryons (asymmetry of ~1.9%) at √s = 900 GeV/c.

22 ALICE is up and running!!! 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 22 THANK YOU FOR YOUR ATTENTION

23 BACKUP 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 23

24 Strangeness (K s 0 ) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 24

25 Strangeness (Λ) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 25

26 Cascades (Ξ) 26.03.2010 Panos.Christakoglou@cern.ch - XXVIII Workshop on Recent Advances in Particle Physics and Cosmology,Thessaloniki 26

Download ppt "First identified particle studies at the CERN-LHC with the ALICE experiment Panos Christakoglou a,b for the ALICE Collaboration 26.03.2010"

Similar presentations

Systematic Error Related to the Transport Model Systematic Error Introduced by the Material Budget Uncertainties Using Geant3 interface (GHEISHA) to transport.

Systematic Error Related to the Transport Model Systematic Error Introduced by the Material Budget Uncertainties Using Geant3 interface (GHEISHA) to transport.
Strangeness analysis in ALICE o genuine p+p physics o PbPb physics o analysis status, studies in PPR2 o prospects K0s and hyperons Ludovic Gaudichet, INFN.

Strangeness analysis in ALICE o genuine p+p physics o PbPb physics o analysis status, studies in PPR2 o prospects K0s and hyperons Ludovic Gaudichet, INFN.
A Very High Momentum Particle Identification Detector for the ALICE experiment at the LHC. Dorado del mar Puerto Rico, April 8, 2012 Edmundo García Chicago.

A Very High Momentum Particle Identification Detector for the ALICE experiment at the LHC. Dorado del mar Puerto Rico, April 8, 2012 Edmundo García Chicago.
Heavy flavor measurements with high-p T electrons in the ALICE EMCal Mark Heinz (for the ALICE Collaboration) Yale University 26 th Winter Workshop on.

Heavy flavor measurements with high-p T electrons in the ALICE EMCal Mark Heinz (for the ALICE Collaboration) Yale University 26 th Winter Workshop on.
Bingchu Huang, USTC/BNL 1 Bingchu Huang (for STAR Collaboration) University of Science and Technology of China (USTC) Brookhaven National Laboratory (BNL)

Bingchu Huang, USTC/BNL 1 Bingchu Huang (for STAR Collaboration) University of Science and Technology of China (USTC) Brookhaven National Laboratory (BNL)
23-09-2004M.Mevius Open and hidden beauty production in 920 GeV proton –nucleus collisions at HERA-B M.Mevius DESY.

M.Mevius Open and hidden beauty production in 920 GeV proton –nucleus collisions at HERA-B M.Mevius DESY.
Particle Production in p + p Reactions at GeV K. Hagel Cyclotron Institute Texas A & M University for the BRAHMS Collaboration.

Particle Production in p + p Reactions at GeV K. Hagel Cyclotron Institute Texas A & M University for the BRAHMS Collaboration.
Source Dynamics from Deuteron and Anti-deuteron Measurements in 200 GeV Au+Au Collisions Hugo E Valle Vanderbilt University (For the PHENIX Collaboration)

Source Dynamics from Deuteron and Anti-deuteron Measurements in 200 GeV Au+Au Collisions Hugo E Valle Vanderbilt University (For the PHENIX Collaboration)
STAR Strangeness production in jets from p+p 200 GeV collisions Anthony Timmins for the STAR Collaboration  Motivation  Analysis  Results  Summary.

STAR Strangeness production in jets from p+p 200 GeV collisions Anthony Timmins for the STAR Collaboration  Motivation  Analysis  Results  Summary.
SQM2006, 03/27/2006Haibin Zhang1 Heavy Flavor Measurements at STAR Haibin Zhang Brookhaven National Laboratory for the STAR Collaboration.

SQM2006, 03/27/2006Haibin Zhang1 Heavy Flavor Measurements at STAR Haibin Zhang Brookhaven National Laboratory for the STAR Collaboration.
THE PHYSICS OF THE ALICE INNER TRACKING SYSTEM Elena Bruna, for the ALICE Collaboration Yale University 24 th Winter Workshop on Nuclear Dynamics, South.

THE PHYSICS OF THE ALICE INNER TRACKING SYSTEM Elena Bruna, for the ALICE Collaboration Yale University 24 th Winter Workshop on Nuclear Dynamics, South.
1 The Study of D and B Meson Semi- leptonic Decay Contributions to the Non-photonic Electrons Xiaoyan Lin CCNU, China/UCLA for the STAR Collaboration 22.

1 The Study of D and B Meson Semi- leptonic Decay Contributions to the Non-photonic Electrons Xiaoyan Lin CCNU, China/UCLA for the STAR Collaboration 22.
Quarkonium and heavy flavour physics with ALICE at the LHC M. Gagliardi (INFN Torino) for the ALICE collaboration 1 Workshop on discovery physics at the.

Quarkonium and heavy flavour physics with ALICE at the LHC M. Gagliardi (INFN Torino) for the ALICE collaboration 1 Workshop on discovery physics at the.
1 OPEN HEAVY FLAVOUR PRODUCTION IN pp COLLISIONS WITH AT LHC Rosa Romita ( ) for the ALICE Collaboration.

1 OPEN HEAVY FLAVOUR PRODUCTION IN pp COLLISIONS WITH AT LHC Rosa Romita ( ) for the ALICE Collaboration.
Sevil Salur for STAR Collaboration, Yale University WHAT IS A PENTAQUARK? STAR at RHIC, BNL measures charged particles via Time Projection Chamber. Due.

Sevil Salur for STAR Collaboration, Yale University WHAT IS A PENTAQUARK? STAR at RHIC, BNL measures charged particles via Time Projection Chamber. Due.
HFT + TOF: Heavy Flavor Physics Yifei Zhang University of Science & Technology of China Lawrence Berkeley National Lab TOF Workshop, Hangzhou, 26-29 April,

HFT + TOF: Heavy Flavor Physics Yifei Zhang University of Science & Technology of China Lawrence Berkeley National Lab TOF Workshop, Hangzhou, April,
Nov2,2001High P T Workshop, BNL Julia Velkovska High pt Hadrons from  sNN = 130 GeV Au-Au collisions measured in PHENIX Julia Velkovska (BNL) for PHENIX.

Nov2,2001High P T Workshop, BNL Julia Velkovska High pt Hadrons from  sNN = 130 GeV Au-Au collisions measured in PHENIX Julia Velkovska (BNL) for PHENIX.
Measurement of J/ψ production in p+p collisions at √s = 500 GeV at STAR experiment Rongrong Ma (BNL) Hard Probes 2015 McGill University, Montreal, Canada.

Measurement of J/ψ production in p+p collisions at √s = 500 GeV at STAR experiment Rongrong Ma (BNL) Hard Probes 2015 McGill University, Montreal, Canada.
ALICE Physics Week, Muenster, 13.02.07 Andrea Dainese 1 Status of B analysis via single electrons Andrea Dainese INFN – Legnaro based on work with: F.Antinori,

ALICE Physics Week, Muenster, Andrea Dainese 1 Status of B analysis via single electrons Andrea Dainese INFN – Legnaro based on work with: F.Antinori,
D 0 Measurement in Cu+Cu Collisions at √s=200GeV at STAR using the Silicon Inner Tracker (SVT+SSD) Sarah LaPointe Wayne State University For the STAR Collaboration.

D 0 Measurement in Cu+Cu Collisions at √s=200GeV at STAR using the Silicon Inner Tracker (SVT+SSD) Sarah LaPointe Wayne State University For the STAR Collaboration.

Similar presentations

Ads by Google