Pixel Results from CRAFT09

U. Langenegger (PSI), G. Giurgiu (JHU)

Pixel General MeetingNovember 10, 2009

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CRAFT09 Analyses

- Gain calibration + Validation – R. Rougny (Antwerpen), U. Langenegger (PSI)

- Pixel hit efficiency - L. Mucibello, R. Rougny, N. van Remortel (Antwerpen)

- Pixel hit resolution – K. Ulmer (Colorado)

- BPIX Lorentz angle – M. Ivova, V. Chiochia (Zurich)

- FPIX Lorentz angle – A. Kumar, A. Godshalk, A. Kharchilava (Buffalo)

- Data/MC comparison – A. Jaeger, V. Chiochia (Zurich), M.Swartz (JHU)

- All analyses done with most recent CRAFT09 reprocessing /Cosmics/CRAFT09-TrackingPointing-CRAFT09_R_V4_CosmicsSeq_v1/RAW-RECO

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Gain Calibration R. Rougny (Antwerpen), U. Langenegger (PSI)

- Pixel thresholds minimized before CRAFT09 → procedure led to significant fraction of negative BPIX pedestals

- After CRAFT09, detector settings changed to fix negative pedestals (Ben Kreis, D. Kotlinski) → new gain calibration taken (run 117680) → fraction of negative pedestals indeed negligible in new calibration:

BPIX FPIX

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Gain Calibration Validation U. Langenegger (PSI), R.Rougny (Antwerpen)

- Analyze post-CRAFT09 data to validate new gain calibration

CRAFT09 data

- Fraction of post-CRAFT09 data

- No problems seen

Runs119226119094119090119088119079119022119017118969118878118762118621

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In http://www.phys.ethz.ch/~ursl/cms/091110/ you can find a higherstatistics version of the CRAFT09-II gain calibration validation. This is still without the SP skim.

CRAFT09-II----------cluster charge: http://www.phys.ethz.ch/~ursl/cms/091110/craft09-II-clusterCharge.psBPIX Landau+Gauss: http://www.phys.ethz.ch/~ursl/cms/091110/craft09-II-bpix.psFPIX Landau+Gauss: http://www.phys.ethz.ch/~ursl/cms/091110/craft09-II-fpix.ps

reprocessed CRAFT09 SP skim---------------------------cluster charge: http://www.phys.ethz.ch/~ursl/cms/091110/reprocessed-sp-data-clusterCharge.psBPIX Landau+Gauss: http://www.phys.ethz.ch/~ursl/cms/091110/reprocessed-sp-data-bpix.psFPIX Landau+Gauss: http://www.phys.ethz.ch/~ursl/cms/091110/reprocessed-sp-data-fpix.ps

The MPV have come down a bit in both BPIX and FPIX, the effect of the slightly lowered gains, visible in the overlayed offline payload comparison for the new and previous gain calibration runs

http://www.phys.ethz.ch/~ursl/cms/091110/gains-108062-117680.png

The relative width has decreased (increased) slightly for the BPIX (FPIX).

The gain calibration looks good

Gain Calibration Validation U. Langenegger (PSI)

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Data / MC Comparison A. Jaeger, V. Chiochia (Zurich)

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Data / MC Comparison – Cluster Charge A. Jaeger, V. Chiochia (Zurich)

- Fair agreement between data and MC- Disagreement at low charge could be explained by lower thresholds in MC than in data- Andreas will produce MC with higher thresholds which match data

barrel barrel

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Data / MC Comparison – Pixel Charrge A. Jaeger, V. Chiochia (Zurich)

barrelbarrel

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Data / MC Comparison – Pixel Hit Probability A. Jaeger, V. Chiochia (Zurich)

- Pixel hit probability calculated as chi2 probability of the matching between the observed cluster shape and the expected template- Fair qualitative agreement between data and MC

→ important test since we plan to use pixel probability to improve tracking (remove bad hits, split merged clusters…)

- Work in progress- re-digitize MC with higher thresholds to match MC- optimize phase space to emulate collisions better

(~4000 electrons)

barrel

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Pixel Hit Efficiency L. Mucibello, R. Rougny, N. van Remortel (Antwerpen)

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Pixel Hit Efficiency L. Mucibello, R. Rougny, N. van Remortel (Antwerpen)

Layer 1 Layer 2 Layer 3

White boxes = known bad modules

low statistics

Eff = Nvalid / (Nvalid + Nmissing)

Pixel sensor efficiency ~ 98.3 – 98.5%

- Will investigate pixel efficiency with strip seeded tracks to avoid biases in efficiency

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Pixel Hit ResolutionK. Ulmer (Colorado)

- Pixel hit resolution measured in CRAFT09 using the “double difference” method- Compare measured resolution with predicted errors from template based cluster parameter

estimator (CPETemplate)

- Resolution in microns : reprocessed original processing measured predicted measured predicted X 18 ± 1 15 ± 1 19 ± 3 15 ± 1 Y 26 ± 1 23 ± 1 32 ± 2 25 ± 2

- Measured resolution about 10-20% worse than predicted by CPE- Will repeat measurements with much better statistics with collisions- Will correct CPE predicted errors to match observed resolution

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BPIX Lorentz Angle – Cluster Size Method M. Ivova, V. Chiochia (Zurich)

E

- Good agreement LA measured in latest and first processing as well as with the PIXELAV Simulation

cot()min = -0.408 +/- 0.002 – latest CRAFT09 reprocessingcot()min = -0.405 +/- 0.003 – first CRAFT09 processingcot()min = -0.397 +/- 0.003 – PIXELAV simulation (M. Swartz)

B field ON B field OFF

LA consistent with zero within 2Lorentz ≈ 22°

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FPIX Lorentz Angle – Cluster Size Method A. Kumar, A. Godshalk, A. Kharchilava (Buffalo)

- Good agreement LA measured in latest and first processing as well as with the PIXELAV Simulation

cot()min = -0.084 +/- 0.008 – first CRAFT09 reprocessingcot()min = -0.080 +/- 0.005 – latest CRAFT09 processingcot()min = -0.081 +/- 0.003 – PIXELAV simulation (M. Swartz)

Lorentz ≈ 5°

LA consistent with zero

B field ON B field OFF

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FPIX Lorentz Angle – Grazing Angle Method A. Kumar, A. Godshalk, A. Kharchilava (Buffalo)

- Buffalo group also measured FPIX LA using grazing angle method in CRAFT08 and got

good agreement with cluster size method

→ nice proof of principle

3.75° ± 0.41° - grazing angle

3.95° ± 0.39° - cluster size

- This is important since with collisions

cluster size method is not adequate

- With collisions grazing angle method

will be used for BPIX

- For FPIX neither grazing angle nor

cluster size are optimal with collision tracks

→ might have to rely on cosmics

only Depth (m)

Avg.

Drift

(mm

)

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Conclusion

- Gain calibration in place and validated with post CRAFT09 data

- Lorentz angles measured and in agreement with previous processing and with PIXELAV simulation

- Pixel sensor efficiency ~98.5%- Next step: use strip seeded tracks to avoid biases

- Reasonable data/MC agreement when collision like cosmic tracksselected but some cosmic specific effects not simulated

- Pixel hit resolution within 10-20% from expectation- Will repeat with collisions and adjust predicted errors if needed

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Backup Slides

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Gain Calibration Validation U. Langenegger (PSI), R.Rougny (Antverpen)

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CRAFT09 data

- Fraction of post-CRAFT09 data

- No problems seen

Gain Calibration Validation U. Langenegger (PSI), R.Rougny (Antverpen)

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