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Preliminary Data Analysis of Cosmic Ray Tracks for Enhanced Angular Resolution

This report presents preliminary data analysis on cosmic ray tracks using CatTrk software, which has been adapted from existing Maverick code. The analysis, conducted at The Ohio State University on March 14, 2006, focuses on 2003 test beam data and newly sourced cosmic ray data, highlighting the efficiency of the modified algorithms in tracking cosmic events. Key findings include issues with track resolution due to chamber voltage settings and the need for improved pulse timing and angular resolution across multiple chambers. Calibration constants and Gatti fits are also discussed.

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Preliminary Data Analysis of Cosmic Ray Tracks for Enhanced Angular Resolution

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  1. Slice Test: Preliminary Data Analysis S. Durkin The Ohio State University CSC ME/1/1 Meeting March 14, 2006

  2. CatTrk Software • Existing Maverick Code used, modified, and check by many people • written to analyze 2003 test beam data • recently converted to CMSSW (only track finding/fitting working) • very fast – 100 cosmic events/second (AMD Sempron 2.5GHz) • Package Includes: • Anode/Cathode Multi-Track Finding Calman Filters • Gatti fits with cross-talk and Auto-Correlation Matrix (3 time X 3 charge bins) • 3-D Track finding to Gatti points using Gatti Error matrix • Track Error Matrix to Determine position/angle uncertainty • Chi-square of Gatti Fits and Line Fits reasonable • Fitting Constants: (averages used for this analysis) • Full Calibration Constants now available thanks to Oana & Nicole • Added to CatTrk software last Friday • Gain, Cross-Talk, AutoCorrelation Matrices in Oracle Data Base • see http://cmsdoc.cern.ch/cms/CSC/CERN/db.html

  3. Cosmic Ray Data • Data with ~ ten live chambers available since September • Few have even touched these data sets • Data obviously not as clean as Test Beam • Low Momentum tracks • Resolution may be effect by multiple scattering • Some very messy cosmic showers interspersed • (in January a DDU error state was tracked to hundreds • of shower tracks arriving within 40sec time period) A Root Event Display was written in to Debug Tracking (following event displays from first two events in September Run 10010)

  4. Black point a knock-on eliminated from line fit.

  5. Poor Track: Angle of line does not match 2 other tracks. Last two points at very edge of Chamber only fit 2 strips.

  6. Large Angle Problem For Cathode Track Angles >30 degrees, hit resolution seen to degrade Gatti Fit Chi-Square 5 D.O.F. <20o Resolutions for hits within 1mm of strip edge Mean ChiSquare Hit pos. – line (strips) >30o Cathode Angle (degrees) Hit pos. – line (strips) Maybe not so surprising. At 30 degrees charge is deposited along ~0.57 cm of wire.

  7. Gatti-Fit Hit Resolution Strip Noise 3.2 ADC Counts • Require > 4 hits on track • Cathode Track Angle < 25 degrees Near Center (poor) (ADC Counts) Very poor – half strip Resolution is 1400 m ME2/2/27 Resolution Estimated From width ignoring tails Charge 4.5 86.0 5.5 Error 71% 3% 60% Sigma (hit pos – trk pos)(m) Between Strips (ADC Counts) Charge -1.0 46.0 41.5 Error - 7% 8% Strip Position

  8. Is 3600V High Enough? 3600V is the average chamber’s plateau knee History: Test Beam Voltages raised to 3650V, 3600V deemed too low! Landau peaks below design: peaks ~(80-110 ADC Counts) Design specs: peak 200 ADC Counts (12 bit ADC – 4096 ADC counts) Need to account for gain variations – within chamber and chamber to chamber… But Must Keep Voltage Low to Insure Long Chamber Life

  9. HV Scan on ME2/2/27 Present trigger does not allow reasonable coverage of all chambers due to complex geometry. Arbitrarily choose one chamber. Many chambers peak even lower. Feb 24, 2006: take data at 3600V, 3650V, 3700V Sum 3 Adjacent Strips (ADC Counts)

  10. Gatti Hit Resolution 100 V increase yields a result much closer to Test Beam ME2/2/27 Sigma (hit pos – trk pos)(m) Rule of Thumb: 150V  2X gain Strip Position

  11. Gain Variation within Chamber Even with Gain constant Resolution is a Strong Function of Strip Width ME2/2/27 3600V Track with Anode Hits in Lower ¼ of Chamber (hit within 1mm Strip Center) Track with Anode Hits in Upper ¼ of Chamber (hit within 1mm Strip Center) • = 0.1 strips • = 1400 m • = 0.042 strips • = 440 m Hit Pos – Line Pos (cm) Hit Pos – Line Pos (cm)

  12. Conclusion • We have 20 chambers live. We do little more than check their data unpacks • without errors. • Presently there is no official CMSSW software beyond data unpacking • We must monitor pulse timing, Landau peaks, layer efficiency … • This NEEDs to Be Done…Now! • Chamber Voltage was set to Lowest Average Plateau Value • Voltages must be increase to get fine enough angular resolution • Average resolution is not good enough • Track resolution must be adequate in full chamber.

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