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HK: Fachverband Physik der Hadronen und Kerne

HK 7: Schwerionenkollisionen und QCD Phasen

HK 7.5: Vortrag

Montag, 19. März 2012, 15:15–15:30, P 5

Magnetic field studies for the measurement of dielectrons with ALICE — •Ole Hinrichs — Institut für Kernphysik, Universität Frankfurt, Germany

The study of dielectrons is an important tool for obtaining information from all phases of ultra-relativistic collisions as they do not undergo strong interactions. The major obstacles in the measurement of dielectrons are the relatively small signal and large combinatorial background, such that one needs a large acceptance and a good particle identification at low transverse momentum. The latter two aspects can be improved by lowering the magnetic field in the central barrel of the ALICE detector from the nominal value of B=0.5T.
We present detailed studies with two different types of simulation to understand and quantify the effect of a reduced magnetic field. First, the full chain of simulation was used: pp collisions were generated with the event generator PYTHIA6 and propagated in a detailed simulation of the ALICE setup with GEANT3. Finally, the particles were reconstructed with the ALICE tracking software within AliRoot. As this procedure requires a huge amount of CPU-time a large number of events were produced with fast simulations. These are based on a parametrization of particle spectra and detector responses. The results of these simulations will be presented and confronted with available data.