Raiders of the lost photons

1
Raiders of the lost photons

• Elisabetta Bissaldi
• University INFN Trieste, Italy
• SLAC, USA

2
Outline

• Introduction
• Photon selection with MC algorithm
• Results from cosmic ray data for integrated
• 2, 4 and 6 towers configurations
• Study of vertex topologies
• Summary

3
g Topologies for Dummies

• Photons
• 2 tracks VERTEX

• Muons
• NO VERTEX ?

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m
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SI
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e-
In TkrRecon 1 track VERTEX
4
g Topologies in real life

• Often one of the 2 tracks is missing!
• No Si hits No Si hits (edge)
• Narrow separation Short track
  Compton
• angle
  scattering

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5
Original idea...

• Bill Atwoods talk presented at the 3rd IA
  Workshop
• in march 2005

• Develop g finding algorithm
• Classification trees
• Monte Carlo samples
• AllGamma
• Surface Muons
• Cosmic ray data sample
• Test RUN 140001338
• for single tower
• ? g candidates sample
• (5 of triggers)

6
BB Challenge

• MC for 1 tower configuration
• Developed Initial selection cuts
• Defined 2 g topologies
• Developed algorithm
• classification trees
• Applied algorithm in data

• MC for 2, 4, 6 towers
• configurations
• Same
• Used only 1 g topology
• Searched for simple cuts using main variables
• Applied cuts in data
• Studied vertex topologies

BILL
BETTA
More details in the next slides...
7
Initial selections

• Same
• Focus on first g topology
• VtxAngle gt 0.
• VERTEX
• Same

• Initial conditions
• TkrNumTracks gt 0
• CalEnergySum gt 10 MeV
• Definition of 2 g topologies
• 3. VtxAngle gt 0. VtxAngle 0.
• VERTEX 1TRACK
• Tkr1ToTFirst gt 1 MIP

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Additional variables

• Tkr1SSDVeto gt 1
• Use Tracker in self Veto Mode to replace ACD
• At least one hit plane before start of track

• same

9
Bills Classification Trees

• Variables used to select g
• Tkr1ToTTrAve
• Tkr1Chisq
• Tkr1SSDVeto
• Tkr1TotFirst
• Tkr2Chisq
• Tkr2FirstChisq
• CalEnergySum

VERTEX TOPOLOGY

From Bills talk
10
Bettas MC/DATA samples

• MC AllGamma
• 1 x 106 events
• 33341 trig. events
• Isotropic
• 18 MeV 18 GeV
• v5r0608p7

• MC Surface Muons
• 4 x 106 events
• 219322 trig. events
• Isotropic
• PDG formula and low energy extension
• v5r0608p7

• DATA Cosmic Rays
• 2 Towers RUN 135002134 (462678 trig. events)
• v5r0608p6
• 4 Towers RUN 135002778 (61996 trig. events)
• v4r060302p23
• 6 Towers RUN 135004075 (390035 trig. events)
• v5r0608p6

11
Tkr1SSDVeto
MC Muons
MC All Gamma
no cuts
no cuts
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt1
Tkr1SSDVetogt2 ?
12
Tkr1SSDVeto
MC Muons
MC All Gamma
no cuts
no cuts
We lose 10 of photons and 70 of muons
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt2
13
Tkr1SSDVeto
MC All Gamma
DATA
no cuts
no cuts
We lose 10 of cosmic ray data
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt2
14
Tkr1ToTTrAve
MC All Gamma
MC Muons
no cuts
no cuts
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt2
Tkr1ToTTrAvegt1.3?
15
Tkr1ToTTrAve
MC Muons
MC All Gamma
no cuts
no cuts
We lose 5 of photons and 70 of muons
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt1 Tkr1ToTTrAvegt1.3
16
Tkr1ToTTrAve
MC All Gamma
DATA
no cuts
no cuts
We lose 20 of cosmic ray data
all cuts
all cuts
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt1 Tkr1ToTTrAvegt1.3
17
2 Towers Results
MC AllGamma MC AllGamma MC Surface muons MC Surface muons DATA Cosmic rays DATA Cosmic rays
STEPS N events N events N events
No cuts 33341 100 219322 100 462676 100
1 47 98 97
2 19 33 32
3 9 1.5 3
4 5.7 0.05 1.6
5 5.3 0.03 1.3
6 1672 5.0 25 0.01 4715 1.0
Similar results were obtained for 4 and 6
towers! (ask me later)
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt2 Tkr1ToTTrAvegt1.3
Cuts are cumulative!
18
2 Towers Results
100 10 1 0.1 0.01
MC AllGamma
5
MC Muons
1
VtxAnglegt0.
DATA
Tkr1SSDVetogt2
Tkr1ToTTrAvegt1.3
0.01
STEPS 1 2 3 4
5 6
Cuts are cumulative!
19
g candidates with Event Display
g dir
hit
tracks
20
g candidates with Event Display
g dir
tracks
21
g candidates with Event Display
g dir
Different Vertex Topologies
tracks
22
Topologies à la carte
g dir
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SI
SI
tracks
?
DOCA Distance Of Closest Approach
23
VtxStatus

• Vertexing Variable in the Merit Ntuple
• Summary of track composition and topology

MC All Gamma 2 Towers
no cuts
?
24
VtxStatus bit pattern
Single track vertex 2 tracks vertex More than 2 tracks in vertex Vertex position set by DOCA point Vertex tracks share first hit Vertex tracks start in different planes DOCA point lies inside track hits VtxStatus Values
0 1 2 3 4 5 6 7 VtxStatus Values
0
1 1
1 16
1 1 34
1 64
1 1 80
1 128
1 1 1 162
1 1 192
1 1 1 208
21 25 27 162
1true
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VtxStatus Distributions
MC AllGamma 2 Towers
all cuts
no cuts
162
0 and 1
2.7 of initial triggers!
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...and with DATA
DATA Cosmic rays 2 Towers
no cuts
all cuts
162
0 and 1
0.6 of initial triggers!
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My friend 162
g dir
g dir
hit
W
hit
SI
SI
tracks
tracks
VtxStatus 162 2 tracks vertex, vertex tracks
share first hit and DOCA point lies inside track
hits
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Energy distribution
DATA 2 Towers
MC AllGamma 2 Towers
all cuts VtxStatus162
all cuts VtxStatus162
TkrNumTracksgt0 CalEnergySumgt10. VtxAnglegt0.
Tkr1TotFirstgt1 Tkr1SSDVetogt1 Tkr1ToTTrAvegt1.3 Vtx
Status162
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Summary

• Developed a simple algorithm to select g in
  cosmic ray data using Bills analysis as a
  starting point
• Learned about how different the g topologies are
  from the simple picture from pair conversion
• Future Work
• ? Possibility to use the selected g sample to
  study the behaviour of the detector with
  different register configurations
• ? Depending on the physics analysis, we may be
  more interested in selected vertex topologies
• Explore this further in my thesis
• Analysis of reprocessed 4, 6 and 8 towers in
  progress...

30
GRAZIE...

• Eduardo
• Bill
• Francesco
• Anders
• Leon
• Eric
• Luis
• ...all other italian summer students
• and people I met at SLAC!

31
Backup slides
32
6 Towers Results
AllGamma AllGamma Surface muons Surface muons Cosmic Data 75 Cosmic Data 75 Cosmic Data 77 Cosmic Data 77
STEPS N events N events N events N events
Recon 89638 100 558757 100 390033 100 389690 100
1 57 98 92 92
2 31 51 45 45
3 15 2 5 5
4 13 0.3 2 2
5 10335 11.5 983 0.18 7588 1.9 7499 1.9
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6 Towers Results
Cosmic Data RUN 135004075 Cosmic Data RUN 135004075 Cosmic Data RUN 135004077 Cosmic Data RUN 135004077
Applied cuts N events N events
Recon 390033 100 389690 100
1. 92.4 92.4
2. 45.5 45.4
3. 10.6 10.7
4. 28.2 28.1
5. 62.9 63.1
1.2. 44.7 44.6
1.2.3. 4.6 4.6
1.2.3.4. 2.4 2.3
1.2.3.4.5. 7588 1.9 7499 1.9
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4 Towers Results
AllGamma AllGamma Surface muons Surface muons
Applied cuts N events N events
Recon 62070 100 391538 100
1. 54.2 97.2
2. 71.2 48.6
3. 28.1 4.9
4. 43.9 6.9
5. 46.6 63.8
1.2. 27.2 45.9
1.2.3. 14.0 2.1
1.2.3.4. 10.1 0.2
1.2.3.4.5. 6171 9.9 608 0.1
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4 Towers Results
Cosmic Data RUN 135002778 Cosmic Data RUN 135002778
Applied cuts N events
Recon 61994 100
1. 97.0
2. 43.4
3. 14.7
4. 31.2
5. 67.6
1.2. 42.7
1.2.3. 6.3
1.2.3.4. 3.1
1.2.3.4.5. 1533 2.5
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6 Towers Results
100 10 1 0.1
AllGamma
Muons
11.5
Data 75 Data 77
1.9
0.18
STEPS 1 2 3
4 5
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4 Towers Results
100 10 1 0.1
AllGamma
9.9
Muons
Data
2.5
0.1
STEPS 1 2 3
4 5
38
Same with MC Muons...
MC Surface Muons
no cuts
0 and 1
1 0
92 3