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Far Detector Performance and Calibration

This report summarizes the performance and calibration activities for the Far Detector during the March-July 2002 period, detailing the analysis of roughly 200 ‘plane trigger’ runs, resolution improvements, and calibration studies. Key activities included timing calibration, timewalk correction, and pulse height normalization using muons. Stability assessments indicate calibrations hold to better than 1 ns, enabling batch data processing and DST production. The report highlights ongoing optimization efforts, detector alignment work, and plans for future analysis, emphasizing the need for broader participation in reconstruction tasks.

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Far Detector Performance and Calibration

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  1. Far Detector Performance and Calibration J. Musser Indiana University Minneapolis, July 2002

  2. 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

  3. 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.

  4. T0 Calibration T0s vs Channel -15 ns < T0 < 15 ns Strip Meantime Timing Residual s= 2.5 ns L/R strip timing vs track position predicts 2.2 ns.

  5. TimeWalk Calibration Pulse-height dependent tail on time residuals - correctable by time walk correction.

  6. Time Walk Correction Mean Time Residual (ns) T' = T - C1/(C2+ADC^1.2) ADC

  7. T0 Stability T0 differences between two data sets separated by 2 months.

  8. T0 Stability (2) Stability is better than 1 ns over this period. However, some statistically significant differences are seen.

  9. Velocity Resolution/Stability Average 1/b RMS vs run, from March to the present. RMS is stable at 8% Average muon 1/b vs run, from March to the present. Average is stable to much better than 1%.

  10. Calibrations (2) Pulse Height • Strip Attenuation (mapper data) • Inter-strip Normalization Using Muons • Stopping Muons Inter-Detector Normalization

  11. Muon Pulse Height Distribution Far Detector Data - Single End Blue: Raw Green: Clear Fiber Atten. Yellow: Strip Atten. Red: Path Length. Black: Inter-Strip Norm.

  12. Inter-Strip Normalization # Events Used in Calibration vs Plane Inter-Strip Normalization Factor Distribution (23% strip-strip gain variations)

  13. Inter-Strip Normalization Mean Resp. vs Plane Raw Mean Resp. vs Plane Corrected

  14. Time Stability of Strip Response*PMT Gain Restricted to first 120 planes (those planes instrumented for entire period under consideration (March 15-July 1) Response is stable to better than 1%

  15. Stopping Muon Calibration

  16. 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.

  17. 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.

  18. Alignment Using Muons (Post Nicolai) Work Presented in 6/02 by R. Lee Single Strip Tracking Uncertainty is ~ 2.3 mm.

  19. Alignment (2) Residual vs Plane - Outlier Planes Identified (some associated with cabling errors)

  20. 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.

  21. Muon Velocity Distribution

  22. Candidate Events

  23. Horizontal Muon

  24. Fully ContainedUp-going Event

  25. 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.

  26. Contained Event Candidate

  27. Contained Event Candidate 2

  28. Angular Distributions - Signal & Background

  29. 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.

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