STS simulations:Layout, digitizers, performance

Radoslaw Karabowicz

GSI

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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 designSilicon 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 (~300m thick, 6cm wide, 2÷6 cm high)with narrow strips (60m): 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 acceptancesensor readout ensured by low-mass microcablessmall sensors in the inner region to reduce the occupancy, outer regions covered by larger sensors, or even chained sensors, to minimize number of channels

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n-XYTER

FEB with8 s

Module

Siliconsensor

Cable

n-XYTER

FEB with8 s

Cable

~6cm

2-6c

m

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Overlaps vs gaps

39.65 40 40.35

Example realizations of the station #3 at z=40cm

gaps

overlapsintermediate

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Overlaps vs gaps – tracking efficiency

Overlap geometry Gap geometry

overall efficiency1 gap, 2 gaps1 overlap, 2 overlaps

Traversing overlaps does notchange tracking efficiency

Traversing gaps doeschange tracking efficiency

Work done by the GSISummer StudentMaksym Zyzak fromNational University, Kyiv

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Overlaps vs gaps – momentum resolution

Overlap geometry Gap geometry

overall resolution1 gap, 2 gaps1 overlap, 2 overlaps

Traversing overlaps does notchange momentum resolution

Traversing gaps doeschange momentum resolution

Work done by the GSISummer StudentMaksym Zyzak fromNational University, Kyiv

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Realistic detector response

The hit is determined by the track position in the center of the silicon detector

Ideal response:

Physical processes:-charge smearing-collection efficiency-Lorentz angle due to magnetic field

Realistic response:

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Realistic response - models

w/2 p/2 transverse tracksCMS @ LHC

CBM: |B| = 1THoles: = 1.5°, x = 8mElectrons: = 7.5°, x = 40m

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Hit density

0-35 hits/cm2 0-31 hits/cm2

0-5.8% 0-11%

Strip occupancy

Ideal Realistic

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<eff> = 98.6%94-100%

<eff> = 91.9%54-99%

1.4-2.3 strips

Cluster length

Hit finding efficiency

Ideal Realistic

1 strip from definition of ideal response

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Realistic response - results

Ideal response: Realistic response:

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Idea

l

14

Rea

listic

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Detector X-ray

x[cm]

y[c

m]

- silicon detector thickness:

currently 0.3% x0 (300m)

- station with cables and support

structure: up to 1% x0

-total vertex/tracking system: < 15% x0

x/x0

x/x0

Radiation length thicknessstation 5 (z = 60cm)

STS detector

6 million 10 GeV/c pions in Geant

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Summary

(more)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 meMore discussion with engineers needed

The realistic digitizer and cluster finder readyDetector response study essential

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Deltas – expected behavior

Station 10.3 e- / beam particle

Station 40.12 e- / beam particle

Station 50.08 e- / beam particle

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Deltas – surprising feature

HEAR MORE ABOUT THIS FROM YOURI’s PRESENTATION

Station 80.03 e- / beam particle

Station 60.15 e- / beam particle

0.05 – 0.1

Station 70.15 e- / beam particle

0.03 – 0.12

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Delta electrons study by Iouri Vassiliev

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Left-right asymmetry

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Hit density

0-35 hits/cm2 0-31 hits/cm2

0-5.8% 0-11%

Strip occupancy

Ideal Realistic

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<eff> = 98.6%94-100%

<eff> = 91.9%54-99%

1.4-2.3 strips

Cluster length

Hit finding efficiency

Ideal Realistic

1 strip from definition of ideal response

STS test beam early results

Radoslaw Karabowicz

GSI

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Sil

ico

nse

nso

r

Test beam setup

Siliconsensor

n-XY

TERFEB w

ith

n-XY

TERFEB with

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First signals from beta source 90Sr

Time in epochs

yiel

d

source source

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First signals from beta source 90Sr

ADC channels

yiel

d

Noise Beta source

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Beam in Cave C!!!

Time in epochs

yiel

d

Playing with threshold

Screams: Do we have beam??

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Beam bunches

time [a.u.] .

HitsBeam counter

Yield

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Channel number correlations

Horizontal strips Vertical strips channel numberon detector 1 on detector 2

ch

anne

l num

ber

Ver

tical

str

ips

Hor

izon

tal s

trip

s

on d

etec

tor

1

on d

etec

tor

2

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Time correlationsbe

am d

etec

tor

time

– hi

t tim

e [a

.u.]

channel number on roc1 (n side)

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Time correlations

Run020

Run015

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Summary

LOTS TO DO!!!to analyze and understand the data

to prepare for next beam time

Conclusions