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Data/MC comparisons

Data/MC comparisons. David Ward Have previously reported on comparison of Feb’05 DESY data with Geant4 Monte Carlos. Issues with upstream material and tracking cutoffs in G4. Here give an update using latest modifications in Geant4 and Mokka. Recent changes to codes .

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Data/MC comparisons

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  1. Data/MC comparisons David Ward Have previously reported on comparison of Feb’05 DESY data with Geant4 Monte Carlos. Issues with upstream material and tracking cutoffs in G4. Here give an update using latest modifications in Geant4 and Mokka. D.R. Ward

  2. Recent changes to codes • Geant4.8.0 – changes to e/m processes to reduce dependence on tracking cutoffs. Find there is no sensitivity to cutoffs in terms of performance and little effect on speed. • Bertini model for Kaons implemented. Need to set G4BERTINI_KAON before comiliation of Geant4 (needed for LCPhys physics list). • Mokka 5.4 is NOT compatible with GEANT4.8.0. Recently received from Paulo a test version “Mokka_G4.8.0” which is. Mokka 5.5 released last night – not yet tested. • Mokka now contains a realistic representation of upstream detectors (scintillators, drift chambers) thanks to Fabrizio Salvatore (~10%X0 of material) D.R. Ward

  3. Hit energy /MIPS All plots 1 GeV electron data / MC Clearly better, but not perfect D.R. Ward

  4. Hit energy - tail D.R. Ward

  5. Total ECAL energy Still 2-3% discrepancy, but much better D.R. Ward

  6. No. hits (0.6 MIP threshold) 3% low D.R. Ward

  7. Energy vs plane Showering a bit late? Upstream material? D.R. Ward

  8. Energy in first layer /MIP ~10% X0 ~15% X0 D.R. Ward

  9. Shower barycentre x /mm Start 1 GeV beam @ z=-10m as a pencil beam. Beam width generated by multiple scattering. Almost correctly. However, for 2, 3 GeV beam, need 5mm spread @ -10m to generate observed width. D.R. Ward

  10. Shower barycentre – y /mm D.R. Ward

  11. Effect on 10 GeV π- showers? • Random angles (isotropic) • Reconstruct clusters using Alex Raspereza’s “TrackwiseClustering” (MAGIC gives similar trends). Energy scaled by truth. • Compare LHEP (G4/Mokka default) with LCPhys (favoured?) hadronic physics list • Geant 4.8.0 has the improved electromagnetic tracking favoured by CALICE data. • Typically see effects of 15-25% varying versions/options. D.R. Ward

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