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Jet Note 8 Meeting 7 th June 2007

Jet Note 8 Meeting 7 th June 2007. N. Davidson. E/p minimum bias update with Athena 12.0.6. 12.0.6 Data. Looked at 12.0.6.1 mc (with 1mm problem) 400k minbias events: trig1_misal1_csc11.005001.pythia_minbias.recon.AOD.v12000601 25k single pions with et=1GeV

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Jet Note 8 Meeting 7 th June 2007

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  1. Jet Note 8 Meeting 7th June 2007 N. Davidson E/p minimum bias update with Athena 12.0.6

  2. 12.0.6 Data • Looked at 12.0.6.1 mc (with 1mm problem) • 400k minbias events: • trig1_misal1_csc11.005001.pythia_minbias.recon.AOD.v12000601 • 25k single pions with et=1GeV • trig1_misal1_mc12.007421.singlepart_singlepi_et1.recon.AOD.v12000601 • 15k single pions with et=10GeV • trig1_misal1_mc12.007422.singlepart_singlepi_et10.recon.AOD.v12000601 • Will repeat with 30 micron samples and compare.

  3. Athena 11 vs 12 AODs • Number of tracks • Track Resolution

  4. Selection of isolated pions (et=1GeV) • Cuts made to remove bias in 11: • Based on tracks: • Number of tracks in event < 15 • ΔR track isolation >0.8 • >=1 B Layer Hit • Based on clusters • Cluster Multiplicity < 4 • Energy difference in cones ΔR=1.0 and Δ R=0.4 < 200MeV • Energy fraction in cone ΔR=0.2 > 0.7xEnergy in cone ΔR=0.4 • Approx. 1 track in 200 survive. (or 1 per 10 events) • For version 12: Can make harder cuts since there are more statistics • Changes: • Removed cut on number of tracks as this was ineffectual • ΔR track isolation >1.0 • magnitude of energy difference in cones ΔR=1.0 and Δ R=0.4 < 100MeV • Approx. same number of tracks surviving • E taken as the sum of caloTopoCluster energies (calibrated to EM scale only) in cone. • Cone size of ΔRcone=0.4 found to be optimal • Track extrapolated to 2nd layer of EM Calorimeter must match at least one cluster within ΔRmatch<0.05 • Require clusters and tracks in |eta|<2.4

  5. Results • An improvement to the E/p bias can be made using a smaller cone size of 0.2 • By requiring an isolated 0.2 cone get E/p comparable to 0.4 cone for the single sample SampleE/p meanRMS -minimum 0.668 0.441 bias -single pion 0.645 0.401 (after cuts) -single pion 0.631 0.409 (before cuts) Error: ±0.007 For Cone 0.2: SampleE/p meanRMS -minimum 0.647 0.441 bias (0.2) -single pion 0.645 0.401 cone 0.4 -single pion 0.639 0.401 cone 0.2 Error: ±0.007

  6. Pions with et=10GeV • approx 1/100 events have a track with 8GeV<pt<12GeV • ¾ with matching cluster within R < 0.05 • ¾ with matching 0.4 Cone Jet within R < 0.2 • Cluster based E/p before cuts • mean = 2.054 (cf. 0.861 single pion) • RMS = 1.592 (cf 0.193 single pion) • Jet based E/p before cuts • mean = 2.78 (cf 1.11 single pion) • RMS = 1.759 (cf 0.213 single pion) • Track isolation cut kills minimum bias tracks • 3k events (out of 400k -> 100 events) • More stats & work needed on this

  7. Pile-up • First look at pile-up sample (from mark) • 5.6 events • Bias to E/p scales with the sum of energy in the event. • Difficult to find events with energy sum similar to single event • Method of cuts to find isolated pion probably not possible • Will need to use some kind of background subtraction

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