d. elia, infn barialice offline week - june 20041 recent results from spd beam test d. elia, r....
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D. Elia, INFN Bari ALICE Offline Week - June 2004 1
Recent results Recent results from SPD beam from SPD beam
testtest
D. Elia, R. SantoroINFN Bari
ALICE Collaboration - SPD Group
D. Elia, INFN Bari ALICE Offline Week - June 2004 2
SPD beam test in 2003 (I)
Table
MWPCQuartz Scintillators
Mini bus 0
Pb-Target
Table: 150 cm
beamMini bus 1
Middle plane
Half stave
158 A GeV/c In beam (104 ions/spill, 15 days)
4 mm thick Pb target
3 days with 120 GeV/c proton/pion beam
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Target: 4 mm Pb Trigger: quartz counter (beam) + 2 cm x 2 cm scintillator (interactions) Mini bus 0, 1: 2 single chips/mini bus mounted in crossed way Middle plane: single chip under study Half-stave: read out through MCM including optical module
2.8 GB of data collected
Half-stave
TargetMini bus 0
Mini bus 1
Middle plane
SPD beam test in 2003 (II)
D. Elia, INFN Bari ALICE Offline Week - June 2004 4
SPD beam test in 2003 (III)
Used for this analysis: proton/pion beam data (detailed understanding of detector behaviour)
D. Elia, INFN Bari ALICE Offline Week - June 2004 5
SPD beam test in 2003 (III)
Minibus 0
Minibus 1
Test chip
Main studies:- alignments, residuals and resolution- cluster analysis- detection efficiency
425 m
50 m
256 rows
32 columns
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SPD beam test in 2003 (III)
Minibus 0
Minibus 1
Test chip
Available samples:- focussed and wide beam data- full scan of threshold settings- tilt angle scan (inclined tracks)
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Alignments
Fine tuning of the alignment for the test plane:- track prediction residuals centering
Alignment of the minibuses and track reconstruction
rms(x) = 117 m(y) = 14.9 m
All cluster tupes:
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Residuals and resolution (I)
Single pixel-clusters:
rms(x) = 121 m(y) = 14.9 m
(x) = 12.6 m(y) = 13.6 m
Double-pixel clusters:
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Residuals and resolution (II)
Residuals for singlepixel clusters:
rms(x) = 121 m(y) = 14.9 m
Spatial precision of the telescope (simulation): telescope 10 m
pixel(x) = 121 m pixel(y) = 11 m
@ VTH = 200
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Impacts vs cluster size
Single-pixel cluster
Double-x-pixel cluster
Double-y-pixel cluster
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X-impacts vs cluster size
Single-pixel cluster
@ VTH = 200
Double-x-pixel cluster
D. Elia, INFN Bari ALICE Offline Week - June 2004 12
X-impacts vs cluster size
@ VTH = 200
= 15 m
D. Elia, INFN Bari ALICE Offline Week - June 2004 13
Y-impacts vs cluster size
Single-pixel cluster
Double-y-pixel cluster
D. Elia, INFN Bari ALICE Offline Week - June 2004 14
Residuals vs threshold (I)
@ VTH=80
(y) = 16.6 m
@ VTH=120
(y) = 17.9 m
@ VTH=200
(y) = 14.9 m
@ VTH=214
(y) = 13.8 m
Single-pixel clusters
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Residuals vs threshold (II)
Double-y-pixel clusters
@ VTH=80
(y) = 21.0 m
@ VTH=120
(y) = 14.1 m
@ VTH=200
(y) = 13.6 m
@ VTH=214
(y) = 15.8 m
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Cluster type studies (I)
1 32 4 5
7
6
9 108
12
11
13
Following classification implemented:
14 = all other types
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Cluster type studies (II)
1 32 4 57
8
VTH = 200
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Cluster type studies (III)
1 32 4 57
8
910
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Cluster type studies (III)
6 11
12
13
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Cluster type studies (IV)
VTH=214
VTH=200
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Cluster type studies (V)
1 32 4 57
8
VTH = 214
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Cluster type studies (VI)
VTH=200
VTH=180
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Cluster type studies (VII)
VTH=140
VTH=120
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Cluster size vs threshold (I)
@ VTH=214 @ VTH=200 @ VTH=160 @ VTH=90
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Cluster size vs threshold (II)
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Efficiency study Event selection:
- 1 cluster on each of the tracking planes
- track crossing the test plane (acceptance limits)
@ VTH>150:
- efficiency 99.9%
Threshold scan study: