The Ohio State University CSC Detector Performance Group Quick Study of Knock-on Electrons Can we remove them ? S. Durkin The Ohio State University CSC Detector Performance Group Feb. 15, 2007 S. Durkin, CSC DPG, Feb. 15, 2007
Knock-on Electrons -PDG Scale factor needed Shape similar Is the dE/dx for testbeam same as MTCC ? Analysis will get more difficult MTCC LHC Rays strongly peaked at low kinetic energy S. Durkin, CSC DPG, Feb. 15, 2007
Can we remove Knock-on Electrons? Will concentrate on Knock-on electronics nearly contained within one wire group or strip Leave the energetic ones to Ingo Today analysis use ME1/1 HV data sample (clean) dE/dx – Charge on Strip: A mess to implement Need to know Landau Peak for each chamber e Expect rays in tail S. Durkin, CSC DPG, Feb. 15, 2007
Can we remove Knock-on Electrons? (cont) Anode Width – 2 Adjacent Hits: e # 2 wire groups dy/dz Completely Hopeless at MTCC Dominates S. Durkin, CSC DPG, Feb. 15, 2007
Can we remove Knock-on Electrons? (cont) Cathode Width – Gatti Chi-Square: Knock-on increases Gatti width Chi-square has to be properly tuned Tuning has been done for ME1/1 and ME3/2 Not included in CMSSW Poor Chi-Square Depends on Angle ! e Typical Bad Chi-Square Event chi-square = 667 charge = 7478 Note: Fast Algorithm can calculate Chi-Square or Width Data Fit 573 589 216 1145 1664 481 884 1535 387 442 625 50 1153 1670 83 1023 1566 33 S. Durkin, CSC DPG, Feb. 15, 2007
Investigation of the Tails red points: Residual > 350m black points: Residual < 350m ME1/1 =120m Cut line: 4500-Q-100*2<0 S. Durkin, CSC DPG, Feb. 15, 2007
Removal of Knock-on Electrons Cut removes 1460/24974= 6% Tail Details (truncated) initial sample initial sample events cut events cuts Cut Remove ~ 50% of Residual Tail S. Durkin, CSC DPG, Feb. 15, 2007
Conclusion We can identify 50% of Knock-on Electrons and Remove them Difficult to implement (Landau peak, tuned 2 (or width)) Must remove remaining Knock-on Electrons with “Outlier” Cuts Standard Statisics theory S. Durkin, CSC DPG, Feb. 15, 2007