1. Slice Test: Preliminary Data Analysis The Ohio State University
S. Durkin
The Ohio State University
CSC ME/1/1 Meeting March 14, 2006
S. Durkin, ME1/1 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
S. Durkin, ME1/1 Meeting March 14, 2006

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)
S. Durkin, ME1/1 Meeting March 14, 2006

4. S. Durkin, ME1/1 Meeting March 14, 2006

5. eliminated from line fit.
Black point a knock-on
eliminated from line fit.
S. Durkin, ME1/1 Meeting March 14, 2006

6. Angle of line does not match 2 other
Poor Track:
Angle of line does not match 2 other
tracks. Last two points at very edge of
Chamber only fit 2 strips.
S. Durkin, ME1/1 Meeting March 14, 2006

7. S. Durkin, ME1/1 Meeting March 14, 2006

8. 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.
S. Durkin, ME1/1 Meeting March 14, 2006

9. Gatti-Fit Hit Resolution
Require > 4 hits on track
Cathode Track Angle < 25 degrees
Strip Noise 3.2 ADC Counts
Near Center (poor)
(ADC Counts)
Very poor – half strip
Resolution is 1400 m
ME2/2/27
Resolution Estimated
From width ignoring
tails
Charge
Error % % %
Sigma (hit pos – trk pos)(m)
Between Strips
(ADC Counts)
Charge
Error % %
Strip Position
S. Durkin, ME1/1 Meeting March 14, 2006

10. 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 ~( 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
S. Durkin, ME1/1 Meeting March 14, 2006

11. 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)
S. Durkin, ME1/1 Meeting March 14, 2006

12. Gatti Hit Resolution 100 V increase yields a result much closer to
Test Beam
Sigma (hit pos – trk pos)(m)
ME2/2/27
Rule of Thumb:
150V  2X gain
Strip Position
S. Durkin, ME1/1 Meeting March 14, 2006

13. Gain Variation within Chamber
Even with Gain constant Resolution is a Strong Function of Strip Width
ME2/2/ V
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
= strips
= 440 m
Hit Pos – Line Pos (cm)
Hit Pos – Line Pos (cm)
S. Durkin, ME1/1 Meeting March 14, 2006

14. 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.
S. Durkin, ME1/1 Meeting March 14, 2006