Far Detector Performance and Calibration

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Far Detector Performance and Calibration

J. Musser

Indiana University

Minneapolis, July 2002

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Summary

• roughly 200 ‘plane trigger’ runs available for analysis in March-July time period.

• A small number of cabling errors have been ‘fixed’ in the plex, reprocessing complete (at IU)

– Improvement in time resolution: ~ 5% velocity resolution now observed.

• Primary Data Analysis/Reconstruction Activities

– Calibration Constant Refinement/Stability Studies

– Demultiplexing Optimization

– Detector Aligmment Studies

– Up-going Muon Searches

– Contained Event Analyses

• The Future

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Calibrations (1) Timing

• T0s: Independent determination by Lee, Musser, Rebel,Tardiff.

• Timewalk: Independent determination by Lee, Musser.

• Studies indicate that calibrations hold at better than 1 ns over the March-July time period.

• Calibration quality is sufficiently good at this time to consider batch data processing and production of DSTs.

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T0 Calibration

T0s vs Channel-15 ns < T0 < 15 ns

Strip MeantimeTiming Residualns

L/R strip timing vs track positionpredicts 2.2 ns.

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TimeWalk Calibration

Pulse-height dependent tail on time residuals - correctableby time walk correction.

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Time Walk CorrectionM

ean

Tim

e R

esid

ual (

ns)

ADC

T' = T - C1/(C2+ADC^1.2)

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T0 Stability

T0 differences between two data setsseparated by 2 months.

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T0 Stability (2)

Stability is better than 1 ns over this period. However, some statistically significant differences are seen.

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Velocity Resolution/Stability

Average muon 1/vs run, from March to the present. Average is stable to much better than 1%.

Average 1/ RMS vs run, from March to the present. RMS is stableat 8%

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Calibrations (2) Pulse Height

• Strip Attenuation (mapper data)

• Inter-strip Normalization Using Muons

• Stopping Muons Inter-Detector Normalization

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Muon Pulse Height Distribution

Blue: RawGreen: Clear Fiber Atten.Yellow: Strip Atten.Red: Path Length.Black: Inter-Strip Norm.

Far Detector Data - Single End

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Inter-Strip Normalization

# Events Usedin Calibration vs Plane

Inter-StripNormalizationFactorDistribution

(23% strip-stripgain variations)

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Inter-Strip Normalization

Mean Resp.vs Plane

Raw

Mean Resp.vs Plane

Corrected

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Time Stability of Strip Response*PMT Gain

Restricted to first 120 planes (those planes instrumentedfor entire period under consideration (March 15-July 1)

Response is stable to better than 1%

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Stopping Muon Calibration

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Demuxing Optimization

• Optimization of ‘IU’ demuxer is ongoing, all pathological events sent to B. Rebel.

• UMN group is working on an alternative demuxer, based on ‘global’ event analysis (rather than event swimming, as in IU code) Status will be reported in this meeting.

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Detector Alignment

• SM1 will be energized in the near future. This makes detector alignment studies very timely. There is now a group of people actively working on this. Results will be presented by Nelson, Lee, Boehnlein, Becker, and Viren at this meeting.

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Alignment Using Muons (Post Nicolai)

Work Presented in 6/02 by R. Lee

Single Strip Tracking Uncertainty is ~ 2.3 mm.

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Alignment (2)

Residual vs Plane - Outlier Planes Identified (some associated with cabling errors)

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Upgoing Muons

• Searches for upgoing muons being conducted by Rebel, Musser, Lee, and Tardiff.

• ~ 6 candidate events (in my analysis)

• Data from March to July 1 now processed.

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Muon Velocity Distribution

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Candidate Events

Run Snarl # PlanesUsed

x (m) L (m)

3281(Roy)

2621 15 0.45 0.34 3.0

4408 1804 35 0.56 0.39 3.4

4428 4007 36 0.97 0.35 2.7

4434 1809 14 0.36 0.25 3.4

4436(Brian 1)

424 42 0.39 0.29 5.5

5378(Brian 2)

14383 108 0.70 0.41 9.5

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Horizontal Muon

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Fully ContainedUp-going Event

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Contained Events

• Most of this work is being conducted by Roy in conjunction with veto shield study.

• Expect ~ 0.7 fully contained, reconstructed events in this data set.

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Contained Event Candidate

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Contained Event Candidate 2

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Angular Distributions - Signal & Background

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The Future

• The state of calibrations and reconstruction is consistent with moving towards batch processing of data, and generation of DSTs.

• Broader participation in reconstruction and analysis is highly desirable. The following steps will be taken to assist in this - thoughts on how we can do better are appreciated:

– Maintainance of a ‘needed task list’ on MINOS web site.

– Improve documentation for reconstruction software.

– Begin batch data processing, making DSTs available to general users.