1. Crosstalk Removal to Improve dE/dX measurements Leo Jenner, UCL

2. In brief Crosstalk removal algorithm Comparison of MC truth to Tracking + Crosstalking Some hitches… Preliminary comparison of MC to data

3. A Cosmic Ray Muon Crosstalk removal helps with Tracking And is also important for correcting dE/dX For relative calibration of the detectors

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 it 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 eneryg deposition combined with photon statistics can lead to crosstalk with very comparable energy to real hits The Crosstalker currently runs as a module in Chris Smith’s CalDetTracker muon tracking code Testing is taking place on Mike Kordosky’s Crosstalking Monte Carlo

5. Number of Crosstalk hits: Truth vs Tracked The crosstalker finds about 82% of the crosstalks hits as I’ve opted for a high purity (>90%)

6. Comparison of MC truth to MC+Tracking For the most part there is good agreement…

7. Number of Hits: Tracked/Truth But only 0.32% of events go to plane 54 or more A close up of the last few planes Shows the discrepancy increasing

8. Last Plane Hit Some of the hits at the end of the track seem to go missing after tracking…

9. 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

10. 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 HitBit: 0Entry: 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

11. Preliminary comparison to data Quite low statistics but it still looks a bit odd

12. Data - Last Plane Hit Even with cut: 10<first strip hit <13 PS Muons, Other off momentum muons coming down the beampipe

13. Conclusion More work to do to optimise Tracking and Crosstalk removal using Monte Carlo Fold crosstalk back into real hits to furter improve MC dE/dX Apply crosstalk removal to data