Roberto ChiericiRoberto Chierici - CERN- CERN

Preliminary results from Preliminary results from test beam datatest beam data

Aim and experimental setup Aim and experimental setup Event reconstructionEvent reconstruction

Pedestal, common mode and noise evaluationPedestal, common mode and noise evaluationCluster findingCluster finding

Module performanceModule performanceS/N, stability, cluster characteristicsS/N, stability, cluster characteristics

Latency scansLatency scansPeak and deconvolution modes: features and Peak and deconvolution modes: features and

observations observations Efficiencies and delay curves Efficiencies and delay curves

Conclusions (still preliminary)Conclusions (still preliminary)

On behalf of the CMS tracker collaborationOn behalf of the CMS tracker collaboration

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Experimental setup Experimental setup

Pitch=183 Pitch=183 mm

w/p~0.25w/p~0.25

Sensor width=500 Sensor width=500 mm

V=300 VV=300 V

25 ns bunch spacing

1 2 3 4 5 6

100 mrad

Non irradiated TOB modules

120 GeV ,

Almost final DAQ setup

25-Oct-2001/3-Nov-200125-Oct-2001/3-Nov-2001

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Event ReconstructionEvent Reconstruction Rough pedestal pedRough pedestal ped00 (n (n00 events) events)

<ADC<ADCii> in time > in time

Refined pedestals and first common mode noise (nRefined pedestals and first common mode noise (n11 events)events)

<ADC<ADCii>, >, ADCADC in time removing strips with pol×(ADC in time removing strips with pol×(ADCii-ped-ped00)>threshold)>threshold

CMNCMN00=<ADC=<ADCii-ped-pedii>> over stripsover strips

Noise determination and better pedestals/CMN (nNoise determination and better pedestals/CMN (n22 events) events) Exclude those strips for which pol×(ADCExclude those strips for which pol×(ADCii-ped-pedii)>K)>KADCADC

CMN=<ADCCMN=<ADCii-ped-pedii>> over strips; pedover strips; pedii= <ADC= <ADCii-CMN> in time-CMN> in time nnii

22= <ADC= <ADCii-ped-pedii-CMN>-CMN>22 in time in time

Loop over eventsLoop over events Remove bad events, determine noisy/dead stripsRemove bad events, determine noisy/dead strips Recalculate CMN; update pedestals and noise after nRecalculate CMN; update pedestals and noise after n00+n+n11+n+n22 events events

Cluster findingCluster finding ssii=ADC=ADCii-ped-pedii-CMN-CMNii consider only those for which s consider only those for which sii/n/nii>2>2 Good clusters if nGood clusters if nstripstrip>0, S>0, Sclcl

11/N/Nclcl11>5>5

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PedestalsPedestalsModule 1

Module 2

Module 3

Module 4

Module 5

Module 6

Plots from G. PásztorPlots from G. PásztorAPV 1APV 1 APV 2APV 2 APV 3APV 3 APV 4APV 4

Module 2

d

eco

nvolu

tion

deco

nvolu

tion

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NoiseNoise

Noise < 3 ADC countsNoise < 3 ADC counts

N N depends upondepends upon

the updatingthe updating

Very stable in Very stable in

space space and and timetime

Module #2: noise for twoModule #2: noise for two

different updating windowsdifferent updating windows

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Corrected dataCorrected data ssii=ADC=ADCii-ped-pedii-CMN-CMNi i ( (CMNCMN~0.3~0.3noise)noise) pedestal runs tell us we correctly estimate our noisepedestal runs tell us we correctly estimate our noise

deviation of a factor 2 only outside 4deviation of a factor 2 only outside 4 regionregion

Pedestal runPedestal run

=1.04=1.04

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Cluster characteristicsCluster characteristics

Unexpectedly large number of strips per cluster !Unexpectedly large number of strips per cluster ! Confirmed by different analyses (Pisa)Confirmed by different analyses (Pisa) Effect not present in July 2000 beam test Effect not present in July 2000 beam test

(but very different settings)(but very different settings)

APV 1APV 1 APV 2APV 2 APV 3APV 3 APV 4APV 4

Module #2Module #2

From Pisa groupFrom Pisa group

S/NS/Nclustercluster~20~20

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Latency scans Latency scans

Detectors 1-2-5-6 kept at optimal latency valueDetectors 1-2-5-6 kept at optimal latency value Latency scans for detectors 3-4 Latency scans for detectors 3-4

Excellent way for studying delay curves and efficiencyExcellent way for studying delay curves and efficiency

Preliminary 1D trackingPreliminary 1D tracking Use 15k muons for alignment of modules (fits to residuals)Use 15k muons for alignment of modules (fits to residuals) Modules 3-5 (4-6) aligned with respect to 1 (2)Modules 3-5 (4-6) aligned with respect to 1 (2) Look for coincident clusters in modules 1-5 (2-6) and build a Look for coincident clusters in modules 1-5 (2-6) and build a

“track” :)“track” :) Look what happens around the intercept (Look what happens around the intercept (10 strips) in modules 3 10 strips) in modules 3

and 4and 4

Averaging over eventsAveraging over events

Scans of all APVs.Scans of all APVs. Alignment procedure as aboveAlignment procedure as above Tracking gives worse performance: use the highest strip in moduleTracking gives worse performance: use the highest strip in module

Runs in deconvolution mode

Runs in peak mode

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Delay curvesDelay curves

deconvolution

undershoot...

Non-ideal APV parameters(VFS=70, Isha=90) asymmetry too efficient 25 ns off peak undershoots

q in 10 strips from theintercepts in modules 3,4 no cluster finding

dependence

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Amplitudes in timeAmplitudes in timeDeconvolution Peak

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Strips in clusterStrips in cluster

Peak

Q

q

q

Cb

Cint

Cint

Cb

Cb

CAC

preampl. shaper

C

L

R

Mode

latency

Symmetric charge sharing (Y)

Asymmetric diffusion (X)

q1 q2

Diffusive component ~ 20% of the total

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Delay curves per strip Delay curves per strip (peak)(peak)

Test beam data ‘faster’ curve for adjacent strips signal propagating on 2 closest strips

X-checked by lab calibration very similar peak ratios

|L-R|/(L+R+T)<0.2

Cal. channel

1

2

(L. Mirabito)(L. Mirabito)

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Delay curve per strip Delay curve per strip (deco)(deco)

Reasonable shape of the hit strip deconvolution nicely tuned

Different output for the neighboring: result of the different pulse shape(input to the deco not anymore a CRRC 50 ns) deconvolution enhances q1/q0

|L-R|/(L+R+T)<0.2

Possible explanation given by the behaviour of the amplifier as R at high frequency: +Cint=h.p. filter to adjacent strips

The shape is expected to be APVparameter dependent !

Consequences for the tracker: position resolution cluster reconstruction two track separation data volume studies going on...

=delay curve

Delay (ns)Delay (ns)

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Cluster finding efficiencyCluster finding efficiency

Excellent efficiency at 75 ns (mod. 3) not too sensitive to the position of the maximum cluster finding much more efficient than charge integral

~99.5%

Still too efficient at 25 ns better tuning of APV parameters

Cluster finding cuts to be optimized… efficiency curve can be adjusted the efficiency ‘plateau’ can be considerably smaller

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Response functionResponse function

Diffusive regionsDiffusive regions

The response function can be The response function can be determined by assuming a uniform determined by assuming a uniform beam intensity beam intensity over the strip:over the strip: diffusion regiondiffusion region position resolutionposition resolution(work is going on…)(work is going on…)

Charge sharingCharge sharing

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ConclusionsConclusions The 25 Oct - 3 Nov test beam on 25 ns beam was a successThe 25 Oct - 3 Nov test beam on 25 ns beam was a success

6 TOB modules tested on a 25 ns beam with the next-to-final DAQ setup6 TOB modules tested on a 25 ns beam with the next-to-final DAQ setup excellent quality of the collected dataexcellent quality of the collected data

Several configurations triedSeveral configurations tried latency scans in peak and deconvolutionlatency scans in peak and deconvolution latency scans with different APV parameterslatency scans with different APV parameters special triggersspecial triggers

Preliminary results very interestingPreliminary results very interesting S/N of clusters ~ 20 (deco, non irradiated detectors), noise as expectedS/N of clusters ~ 20 (deco, non irradiated detectors), noise as expected work going on for optimizing delay curves. Excellent track efficiencywork going on for optimizing delay curves. Excellent track efficiency CCintintAPV at high frequency may cause undesired features (not dramatic)APV at high frequency may cause undesired features (not dramatic)

A lot of things to do...A lot of things to do... Huge amount of data (340 GB on castor) to analyzeHuge amount of data (340 GB on castor) to analyze optimize/distribute common tools for data analysisoptimize/distribute common tools for data analysis further investigations + lab tests to be continuedfurther investigations + lab tests to be continued

Everyone very welcome to join !

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Further infoFurther info

Module #2Module #2

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Two eventsTwo events Zero suppressed infoZero suppressed info

Module tilting visibleModule tilting visible

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Deconvolution...Deconvolution...

22=100 ns=100 ns

22=50 ns=50 ns

22=25 ns=25 ns

CR-RC(CR-RC(11))RC(RC(22)) deconvolutiondeconvolution

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DAQ setupDAQ setup

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Shape vs amplitudeShape vs amplitude Pulse height ratios are stable for different input amplitudes.Pulse height ratios are stable for different input amplitudes.

AmplitudeAmplitude

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Diffusion and sharingDiffusion and sharingDeconvolution Peak

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Some (nice) picture...Some (nice) picture...

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Charge asymmetry in Charge asymmetry in timetime

Deconvolution Peak

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Charge sharing in timeCharge sharing in timeDeconvolution Peak

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AimAim Experimental setup (hardware and software)Experimental setup (hardware and software) Event reconstructionEvent reconstruction

Pedestal and common modePedestal and common mode Noise evaluationNoise evaluation Cluster findingCluster finding

Module performanceModule performance S/N and stabilityS/N and stability Cluster characteristicsCluster characteristics

Latency scansLatency scans Peak and deconvolution mode: features Peak and deconvolution mode: features Efficiency and delay curves per strip Efficiency and delay curves per strip New observationsNew observations Resolution curveResolution curve

Conclusions (preliminary!)Conclusions (preliminary!)

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From Pisa groupFrom Pisa group

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7 entries per track7 entries per track

From Pisa groupFrom Pisa group

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Special runsSpecial runs Trigger changed from 1001 to Trigger changed from 1001 to 00110011

another way to study efficiency off peakanother way to study efficiency off peak

<n>~1.86 <n>~1.552nd cluster

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Further crosschecks Further crosschecks (Pisa)(Pisa)

July 2000July 2000

November 2001November 2001

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S/N in clusterS/N in cluster Pisa resultsPisa results