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Data/ Monte Carlo comparisons for the EMC

Data/ Monte Carlo comparisons for the EMC. Katharine Schofield October 27th 2004. The Task. To make a systematic study of the performance of the EMC Monte Carlo simulation Identify areas where MC can be improved, and where it can be trusted

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Data/ Monte Carlo comparisons for the EMC

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  1. Data/ Monte Carlo comparisons for the EMC Katharine Schofield October 27th 2004

  2. The Task • To make a systematic study of the performance of the EMC Monte Carlo simulation • Identify areas where MC can be improved, and where it can be trusted • Perform data/MC comparisons for different particles: e, µ, γ, π, K…. • Kinematic quantities, event-based quantities (eg Number of crystals with energy deposition), shower shape variables

  3. Radiative Bhabhas • Using BetaPidCalib Package to select a pure sample of radiative Bhabha events • Same selection run on Data and MC • Selection code is in BetaPidCalib/BtaEmcRadBhabhaSample.cc • Looking at neutral clusters (photons) in EMC associated with these events

  4. Data Monte Carlo Kinematic quantities (I) Raw Energy • Shape of raw energy distribution? • Selection effect? • Gamma conversion : mostly Bremsstrahlung, i.e. an e from an ordinary Bhabha event emits a photon due to interaction with the detector material • Difference due to poor modelling of the detector material in the MC?

  5. Kinematic Quantities (II) Theta Theta Ratio • Disagreement of theta at top and bottom of range? • Angular range in MC sample (SP-2400) is 17.9o<<131.1o • Angular cut imposed by BetaPidCalib selection is 15.8o<<140.8o • Tried cutting at 20.9o<<120.3o and re-plotting Eraw (& other variables), but this did not cure any discrepancies between Data/MC – ie, cutting on the range where  DOES agree does not seem to improve agreement in other variables

  6. Raw Energy / Theta (I) ! !

  7. Raw Energy/ Theta (II) • Mismatch of Data/MC looks worst in range 0.25<<0.75 (14.3o<<43.0o), but OK elsewhere • Next thing to try is restricting range even further to 0.75<<2.25 (43o <<128o) to try and get agreement in the raw energy distribution

  8. Data/MC Ratios (I) Raw Energy Theta Phi

  9. Data/MC Ratios (II) ! Lateral Moment E/p No. Crystals

  10. Data/MC Ratios (III) s9s25 Second Moment s1s9

  11. Data/MC Ratios (IV) Zernike20 Zernike42

  12. Conclusions • The root of the discrepancy in Eraw and theta is still not obvious • See if restricting theta to 0.75<<2.25 improves the agreement of Eraw and other variables • LAT discrepancy particularly bad • Need to look at more basic quantities before drawing conclusions on ‘higher level’ shower shape variables

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