2015 ECAL detector performance plots

Abstract: Collection of plots summarizing the ECAL performance on 2015 data. General update of 2012 performance plots available in CMS-DP-2013/007.

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Figure Caption
  ECAL supercluster energy

The two plots show the improvements to the Z→e+e− energy scale and resolution from the incorporation of more sophisticated clustering and cluster correction algorithms (energy sum over the seed 5x5 crystal matrix, bremsstrahlung recovery using supercluster, inclusion of preshower (ES) energy, energy correction using a multivariate algorithm). The invariant mass of the two electrons is reconstructed using all of the 2015 Run 2 ECAL data at B=3.8 T. The energy sum over the seed 5x5 crystal matrix is shown. In general not all of the energy from showering electrons is collected within this region, particularly where there is significant dead material in front of the ECAL. In the barrel, the long tail to lower values of the E5x5 is due to the high fraction of showering electrons in the high-material region at abs(η)>1. The resolution is improved by using the supercluster algorithm, that dynamically includes cluster spread, especially in the 𝜙 direction, for showering electrons. For the endcaps, the energy scale is improved by adding the energy deposited in the preshower to the energy deposited in the crystals. The supercluster estimate is finally corrected by applying a multivariate algorithm which makes use of many ECAL variables, such as the cluster shape of the seed cluster and the characteristics of the most energetic sub-clusters of the supercluster.

-- EmanueleDiMarco - 2015-12-14

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Topic revision: r1 - 2015-12-14 - EmanueleDiMarco
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