Simulation of electromagnetic channels for PANDA at FAIR
Tuesday, 23 September, 2014
This PHD work focuses on simulation studies for future measurements with the PANDA detector at FAIR. In particular, I investigated proton antiproton annihilation reactions with an electron-positron pair production which allow to study the structure of nucleons. One major problem with the studies of such electromagnetic channels is the hadronic background which has cross-sections at least six orders of magnitude larger than the signal, requiring excellent particle identification and good momentum resolution. However the momentum reconstruction for electrons and positrons is degraded due to the emission of Bremsstrahlung photons along their path. In the first part of this thesis, I studied this problem and developed a method based on the correction of the momentum of electrons and positrons event by event, using Bremsstrahlung photons detected in the electromagnetic calorimeter. This method, which has been integrated into PANDAroot, the official PANDA reconstruction code, provides a significant improvement of momentum resolution for electrons, and will be exploitable by any measurement with electron-positron pair in the exit channel. In the second part, I performed a feasibility study of measuring the reaction antiproton p→J/psi π0 using predictions from a model based on pion-nucleon TDAs (Transition Distribution Amplitudes). TDAs are non-perturbative objects that describe the transition between two particles of different nature. For example, pion-nucleon TDAs contain information about the pionic components in the nucleon’s wave function. For this study, I relied on the TDA model to create an event generator, and studied the capability to reject hadronic background. The improvement of the efficiency for the signal due to the Bremsstrahlung correction method was quantified. This study can be used as a basis for a proposal of an experiment with PANDA.