Particle Identification with TRD Prashant Shukla Institute of Physics University of Heidelberg Presentation at International Workshop on TRD 27 th September 2005 at Cheile Gradistei, Romania.

Summary of 1. Implementation of TRD particle ID in reconstruction. 2. Identification of protons and kaons. 3. Particle ID from test beam New methods for improvements in PID. 5. Preparation for analysis of TRD events in Physics Data Challenge Outline

1. Each particle track is assigned with dE/dx signals and position of maximum charge from all 6 planes of TRD. 2. Class AliTRDprobdist contains Detector response or Distributions of dE/dx and MaxTimeBin for electron, pions, muons, kaons and protons between 0.5 GeV to 6 GeV momentum. 3. Probability for a track to be electron or pion or any other particle is assigned to each ESDtrack. Implementaion of TRD PID:

Modification Scheme of ESD and TRD track AliRoot V and v4-02-Release

The dE/dx distribution and the Time Bin of max. Cluster distribution AliRoot V4-02-Release (Modified) electrons (red) and pions (blue) P =2 GeV

Particle probabilities with ESDtrack The combined probability P over all layers is obtained as With ESD track the probabilities are as follows: P[0] for e = Pe/(Pe+Ppi+Pmu+Pk+Pp) p[1] for mu p[2] for pi p[3] for K p[4] for p

Liklihood and efficiency AliRoot V4-02-Release electrons (red) and pions (blue) P=2 GeV L- QX

V4-02-Release (Modified) Pion efficiency vs Momentum

dE/dx dist for Pions, Electrons, kaons and protons Minimum Ionizing Pions (p=560 MeV/c) Truncated Mean (Cluster aplitudes between 5 % and 70%) over all six layers p=560 MeV/c

PID for pions, kaons and protons generated with equal probabilities Submitted for PPR Volume II Chapter 5

V4-02-Release (Modified) TRD signals (p=2 GeV) with beam data 2002 Digits Vs. Data Reconstructed Vs. Data With Tail Cancellation

MACROS for test and generation of Detector response Generating response functions: 1. Run job.sh: Runs AliRoot (sem.C+rec.C) 50 times for Config.C, for 200 pions and 200 electrons. Repeat it all momenta. 2. Run Set5.C to generate files for response functions for electrons and pions. Repeat it at all momenta. 3. Run handata.C to create the function AliTRDprobdist::FillData(). 4. Cut and paste it to the AliTRDprobdist.cxx file at the end.

MACROS for test and generation of Detector response Comparing Digits and beam data: 1. Run digits.sh: Runs Aliroot (sem.C+rec.C) 5 times each for Configpi.C and Config.C. 2. Run TRDDigits00.C to get energy loss distribution histograms for electrons and pions. 3. Run plotdigits1.C to plot Digits and the experimental Data. 4. Run plotdigits2.C to plot Digits and the Reconstructed data. Comparing Reconstructed and beam data: 1. Run job.sh: Runs AliRoot (sem.C+rec.C) 50 times for Config.C, for 200 pions and 200 electrons. 2. Run Set5.C to get energy loss distribution histograms for electrons and pions. 3. Run rplot.C to plot Digits and the experimental Data.

HEAD (25 July) TRD signals (p=2 GeV) with beam data 2002 TRD Digits Reconstructed signals

HEAD (25 July) Number of Clusters per track

Test Beam: Old (2002) and New Data (2004) (4, 6 GeV)

Beam test 2004 : Time Bin of Maximum Charge (p=6 GeV)

Pulse Shape Descrimination Test Beam Data 2004 (p=6 GeV)

Pulse Shape Test Beam Data 2004 (p=6 GeV) Electrons

Pulse Shape Test Beam Data 2004 (p=6 GeV) pions

Pulse slope distribution Test Beam Data 2004 (p=6 GeV)

Pulse shape discriminationTest Beam Data 2004 (p=6 GeV)

Principal Component Analysis Test Beam Data 2004 (p=6 GeV)

Physics Data Challenge : TRD Signal events 10 ( J/  ’) ---->  e- + e+ 10 ( Y, Y’, Y”) ---->  e- + e+ 10 ( Ds and Dbars) ---->  e- + e+ 10 ( Bs and Bbars) ---->  e- + e+ 10 ( Bs and Bbars) -->  J/  --> e- + e+ 10  ---->  e- + e+ 10 Omega  ---->  e- + e+ These are the parameterizations of Ramona Vogt results Given in AliGenMUONlib Underlying Events: Hijingcent1 --> b (0, 5) Hijingper1 -->  b (5, 8.6)

Physics Data Challenge : TRD Signal events 1. Total 5000 X 20 = events will be produced 2. With the aim to Study the efficiencies and resolutions for physics signals after full reconstruction. Aliroot v4-02-Release 1. Ramona Vogt parameterization for J/psi does not work any more ---> Use CDF scaled. 2. J/psi, Upsilon Pt values does not differ from event to event 3. There is new tracking code (impoved) after this version

Cross sections and yields of Quarkonia:  dir /nucleon pair (  b) PbPb 5.5 GeV Calculated by NLO J/  ’   dir /nucleon pair (  b) Y/evt (5% Centrality) e pairs/evt *10^(-3) Y Y’ Y”   dir /nucleon pair (  b) Y/evt (5% Centrality) e pairs/evt L = cm -2 s -1 = 1 mb -1 s - 1

Yields for open charm mesons Pb–Pb collisions at √s NN = 5.5 TeV centrality selection of 5% These values correspond to the average of the result obtained with MRST HO and CTEQ 5M1 parton distribution functions. EKS98 parameterization of nuclear shadowing. D+ D0 Ds+ Lc+  dir /nucleon pair (  b) Total= 45 barn Y/evt (5% Centrality) e pairs/evt (10.18)

Yields for open beauty mesons Pb–Pb collisions at √s NN = 5.5 TeV centrality selection of 5% These values correspond to the average of the result obtained with MRST HO and CTEQ 5M1 parton distribution functions. EKS98 parameterization of nuclear shadowing. B0 B+ Bs0 Lb0  dir /nucleon pair (  b) Total=1.79 barn Y/evt (5% Centrality) e pairs/evt (0.47) B/evt 4.6 B->J/psi / evt e pairs/evt

CDF scaled J/  and Upsilon Pt Distribution: Upsilon Pt Distribution: J/  Pt Distribution:

Invariant Mass of electron pairs: HEAD 25 July Ccbar Bbbar

Invariant Mass of electron pairs: HEAD July 25 Ccbar Bbbar No pt Cut pt Cut = 1 GeV

Summary and Future Outlook 1. Implementation of TRD particle ID in reconstruction. 2. Study of TRD Identification of other particles protons and kaons submitted to PPR Volume II 3. Particle ID from test beam Pulse Shape method gives upto 4 times improvement in pion efficiency. Next: Implement it in Aliroot TRD Reconstruction. 5. TRD events in Physics Data Challenge: v4-02-Release Next: Tag a new version with improved tracking