Particle Identification with TRD
Prashant Shukla
Institute of Physics
University of Heidelberg
Presentation at International Workshop on TRD 27th September
2005 at Cheile Gradistei, Romania.
Outline
Summary of
1. Implementation of TRD particle ID in reconstruction.
2. Identification of protons and kaons.
3. Particle ID from test beam 2004.
4. New methods for improvements in PID.
5. Preparation for analysis of TRD events in Physics Data
Challenge
Implementaion of TRD PID:
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.
Modification Scheme of ESD and TRD track
AliRoot V4-02-09 and v4-02-Release
The dE/dx distribution and the Time Bin of max. Cluster
distribution AliRoot V4-02-Release (Modified)
P =2 GeV
electrons (red) and pions (blue)
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)
L- QX
P=2 GeV
V4-02-Release (Modified)
Pion efficiency vs Momentum
dE/dx dist for Pions, Electrons, kaons and protons
p=560 MeV/c
Minimum Ionizing Pions (p=560 MeV/c)
Truncated Mean (Cluster aplitudes between
5 % and 70%) over all six layers
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
Reconstructed Vs. Data
With Tail Cancellation
Digits Vs. Data
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 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.
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.
HEAD (25 July)
TRD signals (p=2 GeV) with beam data 2002
Reconstructed
signals
TRD Digits
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)
Pulse shape discrimination Test 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 f
---->
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 = 100000 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)
11.7
Y/evt (5% Centrality)
e pairs/evt
0.005*10^(-3)
Y”
0.31
0.02
Y
2.65
0.07
Y’
dir/nucleon pair (b)
0.057
0.15
0.094
Y/evt (5% Centrality)
0.0015
0.004
0.0025
e pairs/evt
L = 1027 cm-2 s-1 = 1 mb-1 s-
0.0001 1
0.000034
Yields for open charm mesons
Pb–Pb collisions at √sNN = 5.5 TeV centrality selection of
5%
D+
D0
Ds+
Lc+
dir/nucleon pair (b)
Total= 45 barn
Y/evt (5% Centrality)
e pairs/evt (10.18)
0.405
22.3
3.8
70.4
4.9
13.4
1.07
These values correspond to the average of the result
obtained with MRST HO and CTEQ 5M1 parton distribution
functions. EKS98 parameterization of nuclear shadowing.
9.0
Yields for open beauty mesons
Pb–Pb collisions at √sNN = 5.5 TeV centrality selection of
5%
B0
B+
Bs0
Lb0
dir/nucleon pair (b)
Y/evt (5% Centrality)
0.34
e pairs/evt (0.47)
0.034
B/evt
B->J/psi / evt
e pairs/evt
1.83
0.19
Total=1.79 barn
1.82
0.19
0.53
0.056
4.6
0.046
0.0030
These values correspond to the average of the result
obtained with MRST HO and CTEQ 5M1 parton distribution
functions. EKS98 parameterization of nuclear shadowing.
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
pt Cut = 1 GeV
No pt Cut
Ccbar
Bbbar
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 2004.
4. 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