Tests of a Particle Flow Algorithm with CALICE test beam data

The studies presented in this paper provide a first experimental test of the Particle Flow Algorithm (PFA) concept using data recorded in high granularity calorimeters. Pairs of overlaid pion showers from CALICE 2007 test beam data are reconstructed by the PandoraPFA program developed to implement PFA for a future lepton collider. Recovery of a neutral hadron's energy in the vicinity of a charged hadron is studied. The impact of the two overlapping hadron showers on energy resolution is investigated. The dependence of the confusion error on the distance between a 10 GeV neutral hadron and a charged pion is derived for pion energies of 10 and 30 GeV which are representative of a 100 GeV jet. The comparison of these test beam data results with Monte Carlo simulation is done for various hadron shower models within the GEANT4 framework. The results for simulated particles and for beam data are in good agreement thereby providing support for previous simulation studies of the power of Particle Flow Calorimetry at a future lepton collider. CALICE 2007 test beam data were used to test the PandoraPFA program. The program capability to recover a neutral hadron energy in the vicinity of a charged hadron was studied. The impact of overlapping of two hadron showers on energy resolution was investigated. The dependence of the confusion error on the distance between a 10 GeV neutral hadron and a charged pion was derived for pion energies of 10 and 30 GeV which are representative of a 100 GeV jet. The comparison of these test beam data results with Monte Carlo simulation was done for LHEP and QGSP BERT physics lists. The probability of correct recovering of neutral hadron energy has been calculated. The dependence of the confusion error on the neutral hadron energy was also studied. The confusion error averaged over 100 GeV jet fragment energies has been estimated for the case of one neutral and one charged hadron.