BNDMarcelRaas - TU Dresden · 2009. 9. 15. · 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05...
12
9/15/09 1 Muon Identification in the ATLAS calorimeters
Transcript of BNDMarcelRaas - TU Dresden · 2009. 9. 15. · 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05...
9/15/09
1 Muon Identification in the ATLAS calorimeters
Why? ATLAS muon system has a
gap at η~ 0.
Calorimeter has coverage there.
Possibility to merge calorimeter muons with spectrometer muons to get better efficiency.
Important for 4μ final states like H->4μ analysis.
9/15/09 Muon Identification in the ATLAS calorimeters
2
Why? ATLAS muon system has a
gap at η~ 0.
Calorimeter has coverage there.
Possibility to merge calorimeter muons with spectrometer muons to get better efficiency.
Important for 4μ final states like H->4μ analysis.
9/15/09 Muon Identification in the ATLAS calorimeters
3
How? Take a track from the inner
detector.
Extrapolate to different calorimeter surfaces and gather the corresponding cells (deposits).
Two ways to tag a muon: 1. Define cuts on deposits. 2. Construct likelihood ratio.
Impose isolation criteria: this kills many fakes.
9/15/09 Muon Identification in the ATLAS calorimeters
4
central calorimeter extended calorimeter
endcap calorimeter
Muon deposits
9/15/09 Muon Identification in the ATLAS calorimeters
5
hMuEMB0
Entries 2915
Mean 12.38
RMS 19.16
0 100 200 300 400 5000
100
200
300
400
500
hMuEMB0
Entries 2915
Mean 12.38
RMS 19.16
hMuEMB0
hMuEMB1
Entries 2870
Mean 108.8
RMS 77.42
0 100 200 300 400 5000
20
40
60
80
100
120
140
hMuEMB1
Entries 2870
Mean 108.8
RMS 77.42
hMuEMB1
hMuEMB2
Entries 2803
Mean 25.09
RMS 41.78
0 100 200 300 400 5000
50
100
150
200
250
300
hMuEMB2
Entries 2803
Mean 25.09
RMS 41.78
hMuEMB2
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
350
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
hMuTileBar0
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
0 1000 2000 3000 4000 50000
20
40
60
80
100
120
140
160
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
hMuTileBar1
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
hMuTileBar2
EM1 HAD1
EM2 HAD2
EM3 HAD3
MS
Cut-based tagging First of all we should find a
signal above some noise threshold. Veto on last layer that track passes through.
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
350
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
hMuTileBar0
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
0 1000 2000 3000 4000 50000
20
40
60
80
100
120
140
160
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
hMuTileBar1
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
hMuTileBar2
9/15/09 Muon Identification in the ATLAS calorimeters
6
Cut-based tagging First of all we should find a
signal above some noise threshold. Veto on last layer that track passes through.
The deposits must not exceed predefined cuts. These are optimized per layer.
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
350
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
hMuTileBar0
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
0 1000 2000 3000 4000 50000
20
40
60
80
100
120
140
160
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
hMuTileBar1
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
hMuTileBar2
9/15/09 Muon Identification in the ATLAS calorimeters
7
Cut-based tagging First of all we should find a
signal above some noise threshold. Veto on last layer that track passes through.
The deposits must not exceed predefined cuts. These are optimized per layer.
Upper cuts are also imposed on the electromagnetic calorimeter to kill punch through electrons.
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
350
hMuTileBar0
Entries 2721
Mean 446.5
RMS 328.8
hMuTileBar0
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
0 1000 2000 3000 4000 50000
20
40
60
80
100
120
140
160
hMuTileBar1
Entries 2642
Mean 1174
RMS 595.4
hMuTileBar1
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
0 1000 2000 3000 4000 50000
50
100
150
200
250
300
hMuTileBar2
Entries 2591
Mean 691.5
RMS 455.3
hMuTileBar2
9/15/09 Muon Identification in the ATLAS calorimeters
8
Other selection criteria
9/15/09 Muon Identification in the ATLAS calorimeters
9
d0/σ(d0)
10 log(pisot /pt) < 0.7
Eisot < 15 GeV
10 log(Eisot /pt) < 0.4
Track quality is guaranteed by:
#SCT + pixel hits > 7,
Pt > 4 GeV,
< 7 (w.r.t. primary vertex).
Track isolation criteria:
Energy isolation:
Results on cosmics Minimal track selection to
assure two hits with η information.
Lower efficiency at large η is an acceptance effect.
!-2 -1.5 -1 -0.5 0 0.5 1 1.5 2
efficiency
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1Simulation
Data
9/15/09 Muon Identification in the ATLAS calorimeters
10
Results on MC Tagging efficiency:
Does not involve efficiency loss due to track selection criteria.
-3 -2 -1 0 1 2 30
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
ttbar (105200)
Fa
ke
s/E
ve
nt
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
0.05
9/15/09 Muon Identification in the ATLAS calorimeters
11
Outlook & conclusions
9/15/09 Muon Identification in the ATLAS calorimeters
12
Calorimeter-based muon tagging can recover muons otherwise lost due to gaps in the muon system.
Ongoing work:
Dress muon with quality flag (../Loose/Medium/(Tight))
When there’s beam:
Will look for successful identifications.
Tune cuts, determine efficiency (although very physics channel dependent).
