Pixel Results from CRAFT09
U. Langenegger (PSI), G. Giurgiu (JHU)
Pixel General MeetingNovember 10, 2009
2
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
3
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
4
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
5
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)
6
Data / MC Comparison A. Jaeger, V. Chiochia (Zurich)
7
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
8
Data / MC Comparison – Pixel Charrge A. Jaeger, V. Chiochia (Zurich)
barrelbarrel
9
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
10
Pixel Hit Efficiency L. Mucibello, R. Rougny, N. van Remortel (Antwerpen)
11
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
12
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
13
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°
14
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
15
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
)
16
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
17
Backup Slides
18
Gain Calibration Validation U. Langenegger (PSI), R.Rougny (Antverpen)
19
CRAFT09 data
- Fraction of post-CRAFT09 data
- No problems seen
Gain Calibration Validation U. Langenegger (PSI), R.Rougny (Antverpen)
20
Top Related