fgt layout simulation results
DESCRIPTION
=1.0. =1.5. =2.0. 1 2 3 4 5 6 FGT disks. e+ shower E T =40 GeV. FGT Layout Simulation Results. Detector requirements Optimal location *) Ability of e+/e- separation Simu GEM response Strip layout *) , occupancy e/h discrimination To-do list - PowerPoint PPT PresentationTRANSCRIPT
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Jan Balewski, MITFGT Project ReviewJanuary 7-8, 2008
1 2 3 4 5 6 FGT disks
=1.0
=1.5
=2.0 e+ shower ET=40 GeV
*) still being finalized
• Detector requirements• Optimal location *)• Ability of e+/e- separation • Simu GEM response• Strip layout *), occupancy• e/h discrimination• To-do list• Summary
FGT Layout Simulation Results
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2FGT Layout and SimulationsJan Balewski, MIT
FGT Requirements
1. Reconstruct charge of e+, e- from W decay for PT up to 40 GeV/c
2. Aid electrons / hadrons discrimination
• Allow for uniform performance for z-vertex spread over [-30,+30] cm
• Fit in geometrical envelope vacated by the West Forward TPC
• Benefit from other ‘central’ trackers: IST, SSD
• Relay on vertex reconstruction and Endcap shower-max hit
• Relay on Endcap towers for energy reconstruction
• Minimize amount of material on the path of tracks
• Align FGT segmentation with TPC sector boundaries and Endcap halves
• Assure relative alignment vs. TPC is double with real particles
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3FGT Layout and SimulationsJan Balewski, MIT
Optimization of FGT Disks Location in Z
Used TPC volumenHits>=5
SSDIST1,2beam
Zvertex=+30cm
Zvertex=0cm
1 2 3 4 5 6 R-‘unconstrained’ FGT disks
1 2 3 4 5 6 1 2 3 4 5 6
a)
b) c)Zvertex=-30cm
=1.0
=1.5
=2.0
En
dca
pE
MC
Barrel EMC
• 5 hits required for helix reco
• FGT sustains tracking if TPC provides below 5 hits
• use TPC, SSD,IST for Zvertex <~0 and <~1.3
• displaced -30< Z_vertex < +30 cm
FGT disks geometry: Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm
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4FGT Layout and SimulationsJan Balewski, MIT
Optimization of FGT Disk Radii Rxy – Z representation
TPCIf nHit>5 EndcapSMD
IST1,2
SSD
FGT 1 2 3 4 5 6
=1.
7
Rxy – representation
Used TPC volume
nHits>=5
=1.
0=
1.5
=2.0
En
dca
p
Zver=0cm
1 2 3 4 5 6 FGT
trac
k = 1
.7
Optimization Criteria
•Each track must cross the vertex and Endcap EMC
•6 FGT disk are needed to provide enough hits for tracks at all and all z-vertex
•Single track crosses less than 6 FGT disks
•Relay on TPC & SSD at ~1
Vertex
‘generous’ FGT disks geometry : Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm
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5FGT Layout and SimulationsJan Balewski, MIT
Revised Compact FGTevery disk plays a role
Critical FGT coverage depends on Z-vertex
Rin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm
Rxy
(cm
)
track
ZVERTEX=-30cm ZVERTEX= 0cm ZVERTEX=+30cm
En
dcap
FGT
Vertex
TP
C
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6FGT Layout and SimulationsJan Balewski, MIT
1 of reco track
FGT Enables Reco of Sign of e+,e-
2mm
Sag
itta
(cm
)
100cm
Y/cm
40cm
20cm
X/mm
1.0Vertex=200m
Endcap SMDhit =1.5mm
reco track
Lim
it fo
r p T
tra
ck
3 FGT hits=70m
0
Sag
itta
(cm
)2mm
2.0 mm
Sagitta=2mm
Wrong Q-signGood Q-sign
Tracks uniform in and pT
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7FGT Layout and SimulationsJan Balewski, MIT
Track & Charge Sign Reco EfficiencyFGT geometry: Rin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm
N0 – thrown electrons, ET=30 GeV
N1 – reco tracks (<3 mrad) N2 – reco tracks w/ correct charge sign(pT from 2D circle fit, ET constrain not used, 1 track/event)
•Track reco efficiency >~80% for up to 2.0• Wrong charge reco <~20% only for > 1.5
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8FGT Layout and SimulationsJan Balewski, MIT
W- PT>20 GeV/c
2008 ConfigurationTPC+vertex+ESMD low efficiency
Large A(W-) for >1.5, FGT EssentialCharge Reco Efficiency Using:
TPC+vertex+ESMD+SSD+IST+FGT *)
*) geometry : Rin=7.5cm, Rout=41cm, Z1…Z6=60…150cm, Z=18cm
Reasonableyield
Largest A
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9FGT Layout and SimulationsJan Balewski, MIT
Detailed Simulation of GEM Response1. ionization and charge amplification2. spatial quantization on GEM foil grid3. charge collection by strip planes4. 1D cluster reconstruction5. Add: time dependence pileup simu
phi-axis strip1 mm
R-a
xis
strip
2 m
m
(R* 40m
1D Cluster finder resolution similar to Ferm-Lab test beam results
Realistic MIP charge profile collected by R- and -strips
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10FGT Layout and SimulationsJan Balewski, MIT
FGT Strip Layout *)Top -layer949 -stripspitch 600m
x
y
Xz 15 deg
Endcap halves
y
x
*) close to final
Essential for PT reco
~ 50% transparency
needed for 3D track recognition, resolving ambiguities
FGT quadrant boundariesmatch to Endcap
segmentation
326
R-s
trip
s
Bottom R-layerpitch 800m
Compact FGTRin=18cm, Rout=37.6cm, Z1=70cm, …,Z6=120cm, Z=10 cm
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11FGT Layout and SimulationsJan Balewski, MIT
Estimation of Strip Occupancy
Track rate per strip for minB PYTHIA events @ s500 GeVBased on FGT geometry: Rin=15cm, Rout=41cm
R-strips45 deg long
2
0
1
trac
ks
R=41cm R=15cm =0 deg =90
1 track/strip
per 1000
minB events
trac
ks
0.8
0
0.4
1
-strips 400 m pitch
• pileup from minB events dominates•1.5 minB interactions/RHIC bXing• 300nsec response of APV 3 bXings pile up
Total pileup of 5 minB events per trigger event
• 1 track per FGT quadrant per minB event (scaled from simu below)
• Cluster size: 1mm along , 2mm along R
• Cluster occupancy per triggered event per quadrant • -strips (span ~43cm) 1.2% occupancy• R-strips (span 25cm) 4% occupancy(uncertainty factor of 2)
minB PYTHIA event @ s=500 GeV
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12FGT Layout and SimulationsJan Balewski, MIT
e/h Discrimination : PYTHIA Events
Hadrons from PYTHIA M-CQCD events
e+, e- from PYTHIA M-C
W-events
Isolation & missing-PT cutssuppress hadrons by ~100
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13FGT Layout and SimulationsJan Balewski, MIT
GeV
e/h Endcap EMC additional factor of 10
Projective tower
PreShowers
PostShower
ShowerMax
Shower from electron
E=30 GeV
=2.0
=1.08
Simu of Endcap response toElectrons (black) & charge pions (red) with ET of 30 GeV
Endcap+
e+
30 GeV0
+ e+
GeV
+
e+
~15 GeVE T Trigger
threshold
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14FGT Layout and SimulationsJan Balewski, MIT
e+, e-
M
IP
TPC 6<P<8 GeV/c
e+, e-
MIP
TPC 10<P<14 GeV/c
Endcap-based cuts Identified e+,e- in p+p 2006
Real Electrons Reconstructed in Endcap proof of principle
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15FGT Layout and SimulationsJan Balewski, MIT
To-do List
• completion of detailed (a.k.a. ‘slow’) simulator for GEM response
• develop 3D tracking with pattern recognition, integrate w/ STAR tracking
• include pileup from 3 events in reco of physics events
• implement and optimize full array of e/h discrimination techniques
• completion of full W event simulation and comparison to full hadronic QCD
events simulation
• determine background contribution from Z0 and heavy flavor processes, above
pT>20 GeV/c
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16FGT Layout and SimulationsJan Balewski, MIT
FGT Simulation Summary
1. Will be able to reconstruct charge of e+, e- from W decay for PT up to 40
GeV/c with efficiency above 80%
2. There is enough information recorded to discriminate electrons against hadrons
• Allow for uniform performance for z-vertex spread over [-30,+30] cm, OK• Will fit in geometrical space• Will use hits from IST, SSD• Will relay on vertex reconstruction and Endcap shower-max hit & energy• FGT quadrants are aligned with TPC sector boundaries and Endcap halves• FGT disks 1 & 2 overlap with TPC allowing relative calibration
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17FGT Layout and SimulationsJan Balewski, MIT
BACKUP
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18FGT Layout and SimulationsJan Balewski, MIT
Track Reco Strategy1. Select EMC cluster with large energy (ET>15 GeV)
2. Find Endcap SMD cluster location ( x~y~5cm)
3. Find transverse vertex position (x~y~0.2mm)
4. Eliminate all FGT hits outside the cone: vertex SMD hit
5. Resolve remaining ambiguities (if any) by
comparing R vs. charge
1 2 3 4 5 6 FGT
1
3
5
2
4xx
x
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19FGT Layout and SimulationsJan Balewski, MIT
TPC reco with 5 points
‘regular’ tracking5-hits tracking
‘regular’ tracking5-hits tracking
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20FGT Layout and SimulationsJan Balewski, MIT
Alternative Snow-flake Strip Layout
As in Proposal
12-fold localCartesianref frame
326
R-s
trip
sTop -layer949 -stripspitch 600m
Bottom R-layerpitch 800m
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21FGT Layout and SimulationsJan Balewski, MIT
FGT Material budget UPGR13, maxR=45 cm
Z vert= - 30cm Z vert= 0cm Z vert= + 30cm
0
0.5*Xo
0
Non-FGTmaterial upfront
Non-FGTmaterial upfront
Non-FGTmaterial upfront
0.5*Xo
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22FGT Layout and SimulationsJan Balewski, MIT
Study of stability of efficiency
Studied variations of efficiency (shown in proposal):
- degraded FGT cluster resolution (80m 120m, OK)
- reduced # of FGT planes (6 4 , bad, too few hits/track)
- degraded transverse vertex accuracy (200m 500m, OK)
- FGT cluster finding efficiency (100% 90%, OK , details)
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23FGT Layout and SimulationsJan Balewski, MIT
Detailed Simulation of GEM Response (1)1. ionization and charge amplification2. spatial quantization on GEM grid3. charge collection by strip planes4. 1D cluster reconstruction
Primaryionization
Amplified signal is displaced
Hole in GEM foil amplifies charge
cloud
phi-axis strippitch=600m
R-a
xis
strip
Pitc
h=80
0m
x hit
Latice attractorsspaced 130 m
Charge from this hexagon is attracted by the hole
best
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24FGT Layout and SimulationsJan Balewski, MIT
Simulated FGT Response (2)
22 eV/pair
(760 eV/ track)14 prim pairs/track
32 any pairs/track
22 eV/pair 14 prim pairs/track
R=122mR*=40m
GE
M r
esp
on
se1D
Clu
ster
fin
der
res
olu
tio
n Test beam data