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2 Oct 2003 UCL 2nd Year Talk 1 Crosstalk Removal to Improve Muon dE/dX Measurements Leo Jenner, UCL

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2 Oct 2003 UCL 2nd Year Talk 2 In brief Crosstalk removal algorithm Comparison of Tracking + Crosstalking to MC truth Some hitches… Preliminary comparison of MC to data

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2 Oct 2003 UCL 2nd Year Talk 3 A Cosmic Ray Muon Crosstalk removal helps with Tracking and is also important for correcting muon dE/dX for relative calibration of the MINOS detectors.

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2 Oct 2003 UCL 2nd Year Talk 4 CrossTalk Algorithm Work through all the hits in a given pair of planes and look at the 8 pixel window around each ‘test’ hit Sum the charge and identify the largest hit in the window The test hit is flagged as crosstalk if its charge is less than the sum of the pixels around it, multiplied by a user definable factor. This is usually set to 1 for beam/cosmic muons since low energy deposition combined with photon statistics can lead to crosstalk with very comparable energy to real hits The Crosstalker currently runs as a module before the CalDet muon tracking code Testing is taking place on Crosstalking Monte Carlo

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2 Oct 2003 UCL 2nd Year Talk 5 Number of Crosstalk hits: Truth vs Tracked The crosstalker finds about 82% of the crosstalk hits as I’ve opted for a high purity (>90%)

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2 Oct 2003 UCL 2nd Year Talk 6 dE/dX from Monte Carlo (Truth and Tracked)

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2 Oct 2003 UCL 2nd Year Talk 7 Comparison of MC truth to MC+Tracking For the most part there is good agreement…

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2 Oct 2003 UCL 2nd Year Talk 8 Number of Hits: Tracked/Truth A close up of the last few planes shows the discrepancy increasing But only 0.32% of events go to plane 54 or more…

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2 Oct 2003 UCL 2nd Year Talk 9 Last Plane Hit Some of the hits at the end of the track seem to go missing after tracking…

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2 Oct 2003 UCL 2nd Year Talk 10 Very curvy muons In the third plot along the two blue hits at the end of the track are genuine track hits Maybe the muon curves sharply to the left and travels in the air gap between planes The tracker doesn’t nominally find the last hit because it falls outside of the search window Noise also creates spurious hits at the end of the track

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2 Oct 2003 UCL 2nd Year Talk 11 Preliminary comparison to data Quite low statistics but it still looks a bit odd

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2 Oct 2003 UCL 2nd Year Talk 12 Data - Last Plane Hit Even with cut: 10

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2 Oct 2003 UCL 2nd Year Talk 13 Conclusion More work to do to optimise Tracking and Crosstalk removal using Monte Carlo Fold crosstalk back into real hits to further improve MC dE/dX Apply crosstalk removal to data

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2 Oct 2003 UCL 2nd Year Talk 14

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2 Oct 2003 UCL 2nd Year Talk 15 Anomalies Entry: 2340943 Record: 3107 End: A Plane: 48 Strip: 8 HitBit: 786432 PE: 5.86536 TrackEnd: B Plane: 48 Strip: 8 HitBit: 786432 PE: 7.3501 Entry: 2340944 Record: 3107 eventnum: 3107 Entry: 2340945 Record: 3107 eventnum: 3107 : End: B Plane: 54 Strip: 10 HitBit: 0 PE: 0.935773 Entry: 2340946 Record: 3107 eventnum: 3107 There is an unphysical hit of nearly 1pe… it’s ignored by the truth (see above) but the tracker finds it

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2 Oct 2003 UCL 2nd Year Talk 16 Number of Hits Truth vs Tracked

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