Progress and status of the ssd
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Progress and status of the SSD. Jörg Reinnarth - SUBATECH STAR Collaboration Meeting Warschaw, Poland August 2005. What is the SSD. SSD. SVT. SSD = Silicon Strip Detector Proposed and designed to enhance the STAR tracking capabilities in the central region

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Progress and status of the ssd

Progress and status of the SSD

Jörg Reinnarth - SUBATECH

STAR Collaboration Meeting

Warschaw, Poland

August 2005


What is the ssd

What is the SSD

SSD

SVT

  • SSD = Silicon Strip Detector

  • Proposed and designed to enhance the STAR tracking capabilities in the central region

  • Improve reconstruction efficiency

    short-lived particles such as Λ and Ω

  • 20 ladders x 16 modules = 320 modules

  • Double-sided silicon, 20m in r, 700m in z, -1< η< 1

TPC


Ssd one year ago

SSD one year ago

  • One year ago…

    • All 20 ladders installed at STAR

    • Ladders were tested

    • Noise problems reduced

    • Complete MC-Geometry done

    • SSD added to online histogramms

    • Since Jan 2005 SSD in the run

+

=


Ssd in run 05

SSD in Run ‘05


Ssd in run 051

SSD in Run ‘05

  • During Cu+Cu runs SSD worked very well

  • 74 millionCu+Cu200 TPC events; 57 million with TPC+SSD

  • 77% of all TPC events include the SSD; 67% SSD+SVT

  • 90% of the SSD were working properly (2 ladder off)

  • 93% of all CuCu62 TPC events include SSD; 90% SSD+SVT

  • Then in pp problems started to occur:

  • First: Low voltage problems on power supply side

  • Next: While working the SSD slowed down whole system

  • Air compressor was frequently infault

  • Finally:Major CAEN problem, no high voltage

  • Since middle of June the SSD is no longer in the runs

  • 41 million p+p events with SSD; 24% of all p+p TPC events


Ssd hits with svt and tpc

SSD hits with SVT and TPC

pp

CuCu200

CuCu62

CuCu200 MinBias

CuCu62 MinBias

pp MinBias

pp

CuCu200

CuCu200 HighTower

ppProduction


Pedestal noise in run 05

Pedestal & noise in Run ‘05

Cu+Cu 62

p+p

Cu+Cu 200

CuCu200

Noise higher than in Run `04

Finer study to be done

Cu+Cu 200

Cu+Cu 62

p+p


Software progress

Software progress


Progress and status of the ssd

Data analysis with SSD

Soon future

Still needed:

Alignment

Tracking real data

PointMaker

Ready, ntuple & histo outputs

MySQL database connection

DbMaker DaqMaker StSsdUtil

No more direct connection

Simulation chain

Code completed

Simulated data exist

Tracking

Works, first tests,

tuning on simulated data

alignment needed

Alignment

Histos and fits created

Simulated data help align

Calibration

Pedestal, noise, gain done

Dead strip list needed

T

O

D

A

Y

T

O

D

A

Y

PointMaker

Incorrect Clusterfinding

No MySQL database connection

DbMaker DaqMaker StSsdUtil

direct database connection

Simulation chain

Old and incomplete code

Tracking

Never used, Code not usable

Tracking not tuned

Alignment

Data behave strange

Calibration

No gain calib., no mapping

F

E

B

0

5

F

E

B

0

5


Progress in detail results obtained so far

Progressin detail+Resultsobtained so far


Ssd chip calibration

SSD chip calibration

  • Calibration needed for:

  • particle identification (dE/dx)

  • cluster matching

H

L

X

X

  • Cluster matching

  • Package algorithm works

  • 70% cluster (1 or 2 strips)

  • 80% of case: package 1-n

  • 20% ambiguos hits

  • Cluster matching works

  • but: needs calibration

X

X

X

X

X

H

L


Ssd landau distribution for real data

SSD (Landau distribution for real data)

Max = 0.78

Max = 0.9

Different individual

Landau distributions

Overall gain calibration

needed


Calibration through pulser runs

Calibration through pulser runs

4 Channel per ladder pulsed

Pulser not working


Ssd calibration

SSD calibration


Ssd ittf tracking with ssd

SSD (ITTF tracking with SSD)


Ssd alignment

SSD Alignment

  • Alignment needed to get correct SSD position

  • Installation and ladder exchange move the ladder and wafer from their measured positions

  • Alignment software is ready

  • Technique: Plot residuals in x, y against , z, etc.

    (e.g. Residual in x:

    Local x track position on wafer – local x hit position = Δx)

    → Residual in x, y expected to be distributed around zero

    → SSD shift in one direction: residual → sinus distribution

    → Rotation: x-residual constantly shifted

    Alignment needed for tracking

Δx

Δy


Ssd alignment1

SSD Alignment

φ

Δx

φ

Global alignment

after correction


Ladder alignment through simulation

Ladder alignment through simulation

Δx

Δx

z

z

MC with Δy = 0.2 → Slope

Real data: No slope but Δx shift

→ Shift ladder with Δx = 0.043

Negative slope

→ Shift ladder with Δy = -0.5

Δx

z


Different data sets same parameters

Different data sets, same parameters

Primary tracks: field data

Primary tracks: reversed field

Global tracks: no field

Not consistent data !


Alignment not completely from scratch

Alignment not completely from scratch

dX

dY


Ssd outlook

SSD Outlook

  • Alignment has to be finished

  • Calibration table will be implemented

  • Tracking will be persued

    When SSD alignment and calibration is complete:

  • Request for the SSD in the next production

  • Tracking efficiency will be determined

  • Impact on the detection efficiency will be evaluated


Ssd for upcoming runs

SSD for upcoming runs

  • In August/September ´05 a team will be at BNL

  • Low voltage problems

  • High voltage problems (exchange CAEN)

  • Ladder 8 (permanent high voltage problem)

  • Ladder 7 pedestal setting problem (board?)

  • Overall noise has to be reduced (like run ´04)

  • SSD will be opened at the EAST plattform


Alignment problem

Alignment problem

  • Did global alignment

  • Do ladder by ladder alignment

  • Plot and fit histogramms and compare to simulated behavior

  • Correct shifts and rotations like predicted from simulated data

This does not work. Data do not behave like predicted


Ssd number of clusters

SSD (Number of clusters)

P side

N side


Ssd pedestal noise distribution

SSD pedestal & noise distribution

Pedestal per Chip

Mean noise per chip

/128!

/128!


Simulate the alignment

Simulate the alignment

Δx

Δx

φ

z

Move whole barrel Δy = 0.2

φ

Δx

Δx

z

φ


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