Darmstadt 2016 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 2: Heavy Ion Collision and QCD Phases I

HK 2.1: Gruppenbericht

Montag, 14. März 2016, 14:00–14:30, S1/01 A01

Dilepton reconstruction in Au+Au collisions at 1.23A GeV with HADES — •Patrick Sellheim for the HADES collaboration — Goethe-Universität Frankfurt

In continuation of a systematic investigation of the emissivity of strongly interacting matter, HADES has recently measured the di-electron emission in Au+Au collisions at 1.23A GeV beam energy. Due to the high track density reached for this collision system, different reconstruction strategies have been pursued to achieve optimal reconstruction efficiencies and purities. Electron (positron) candidates have been identified by means of an multi-variate analysis, where the neural network has been trained alternatively based on clean signal and background tracks from data and by simulated tracks. Moreover, the electron track candidates have been matched to rings using ring parameters of found rings or, alternatively, track candidates identified by time-of-flight only have been matched to ring signatures without running the ring finder before.
This contribution will present the results of these analysis procedures and will discuss systematic uncertainties obtained. The statistics is sufficient to investigate double-differential distributions, like centrality dependence covering 45% most central events or transverse momentum distributions for different regions in invariant mass. Special emphasis will be given to the extraction of the radiation from the dense phase of the collision.
This work has been supported by BMBF(05P12RFGHJ,05P15RFFCA), GSI, HIC for FAIR, HGS-HIRe and H-QM.