Transcript sts - JINR

STS simulations:
Layout, digitizers, performance
Radoslaw Karabowicz
GSI
STS detector
Tracking detector:
- low-mass detector
- full azimuthal angle coverage
- polar angle coverage:
from 2.5° to 25°
- high track density in the
inner-most region
- high collision rate
- vertical magnetic field
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STS design
Silicon Tracking System:
8 stations (at 30, 35, 40, 50, 60, 75, 90 and 100cm
away from the target)
build from micro-strip double-sided silicon
sensors
(~300mm thick, 6cm wide, 2÷6 cm high)
with narrow strips (60mm):
vertically oriented on the front side and
slightly rotated on the back side (by 15°)
readout electronics located in the bottom and top
parts outside of defined acceptance
sensor readout ensured by low-mass microcables
small sensors in the inner region to reduce the
occupancy, outer regions covered by larger
sensors, or even chained sensors, to minimize 3
number of channels
Module
FEB
FEB
with
with
n-XY
8 n-XY
8
s s
TERTER
2-6cm
Cable
Cable
Silicon
sensor
~6cm
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Overlaps
vs gaps
gaps
Example realizations of the
station #3 at z=40cm
overlaps
intermediate
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39.65
40
40.35
Overlaps vs gaps – tracking efficiency
Overlap geometry
Gap geometry
Traversing overlaps does not overall efficiency Traversing gaps does
1 gap, 2 gaps
change tracking efficiency
change tracking efficiency
1 overlap, 2 overlaps
Work done by the GSI
Summer Student
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Maksym Zyzak from
National University, Kyiv
Overlaps vs gaps – momentum resolution
Overlap geometry
Gap geometry
Traversing overlaps does not overall resolution Traversing gaps does
change momentum resolution 1 gap, 2 gaps
change momentum resolution
1 overlap, 2 overlaps
Work done by the GSI
Summer Student
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Maksym Zyzak from
National University, Kyiv
Realistic detector response
Ideal response:
Realistic response:
The hit is determined by the track
position in the center of the
silicon detector
Physical processes:
-charge smearing
-collection efficiency
-Lorentz angle due to magnetic
field
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Realistic response - models
CMS @ LHC
w/2 p/2
transverse tracks
CBM:
|B| = 1T
Holes:
Q = 1.5°, Dx = 8mm
Electrons: Q = 7.5°, Dx = 40mm
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Ideal
Realistic
Hit
density
0-35 hits/cm2
0-31 hits/cm2
Strip
occupancy
0-5.8%
0-11%
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Ideal
Realistic
Cluster
length
1 strip from
definition of ideal
response
1.4-2.3 strips
Hit finding
efficiency
<eff> = 98.6%
94-100%
<eff> = 91.9%
54-99%
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Realistic response - results
Ideal response:
Realistic response:
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Ideal
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Realistic
Detector X-ray
station 5 (z = 60cm)
x/x0
y[cm]
Radiation length thickness
6 million 10 GeV/c pions in Geant
x/x0
STS detector
x[cm]
- silicon detector thickness:
currently 0.3%
x0 (300mm)
- station with cables and support
structure: up to 1%
x0
-total vertex/tracking system: <
15% x0
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Summary
Realistic geometry that matches recent
discussions on construction possibilities
available (thanks to Sergey Belogurov)
The geometry has been tested by Irina
Rostovtseva, Maksym Zyzak and me
More discussion with engineers needed
(more)
The realistic digitizer and cluster finder
ready
Detector response study essential
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Deltas – expected behavior
Station 1
0.3 e- / beam particle
Station 4
0.12 e- / beam particle
Station 5
0.08 e- / beam particle
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Deltas – surprising feature
Station 6
0.15 e- / beam particle
0.05 – 0.1
Station 7
0.15 e- / beam particle
Station 8
0.03 e- / beam particle
0.03 – 0.12
HEAR MORE ABOUT THIS FROM YOURI’s PRESENTATION
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Delta electrons study by Iouri Vassiliev
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Left-right asymmetry
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Ideal
Realistic
Hit
density
0-35 hits/cm2
0-31 hits/cm2
Strip
occupancy
0-5.8%
0-11%
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Ideal
Realistic
Cluster
length
1 strip from
definition of ideal
response
1.4-2.3 strips
Hit finding
efficiency
<eff> = 98.6%
94-100%
<eff> = 91.9%
54-99%
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STS test beam early results
Radoslaw Karabowicz
GSI
Silicon
sensor
Test beam setup
Silicon
sensor
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yield
First signals from beta source 90Sr
source
source
Time in epochs
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yield
First signals from beta source 90Sr
Noise
Beta source
ADC channels
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yield
Beam in Cave C!!!
Screams: Do we have beam??
Playing with
threshold
Time in epochs
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Beam bunches
Hits
Beam counter
Yield
time [a.u.]
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Vertical strips
on detector 1
channel number
Horizontal strips
on detector 2
Channel number correlations
Horizontal strips
on detector 1
Vertical strips
on detector 2
channel number
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beam detector time – hit time [a.u.]
Time correlations
channel number on roc1 (n side)
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Time correlations
Run020
Run015
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Summary
Conclusions
LOTS TO DO!!!
to analyze and understand the data
to prepare for next beam time
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