Electron identification with a likelihood method and measurements of di-electrons for the CBM-TRD

  • In this work a likelihood method has been implemented and investigated as particle identification algorithm for the CBM-TRD. The creation of the probability distributions for the likelihood method via V0-topologies seems to be feasible and the purity of the obtained samples is sufficient for the usage in the likelihood method. The comparison between the ANN and the likelihood method shows no differences in the identification performance. The pion suppression factor reaches the same values for the same electron identification efficiencies and the yields of the resulting di-lepton signals are comparable. The signal-to-background ratios for both methods have the same values and show a value of about 10−2 in the invariant mass range of minv = 1.5 - 2.5 GeV/c2, which is expected to be sufficient to provide access to the thermal in-medium and QGP radiation. The investigation of a detector system without a TRD shows no pion suppression for a momentum above p = 6 GeV/c. Therefore, the background contributions increase drastically and the signal-to-background ratio decreases at all invariant masses, but especially in the invariant mass range of minv = 1.5 - 2.5 GeV/c2. The background contributions in the invariant mass range of minv = 1.5 - 2.5 GeV/c 2 are also influenced by the selected electron identification efficiency of the TRD, which significantly shifts the fraction of the eπ contributions relative to the total number of pairs.

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Author:Etienne BechtelGND
Publisher:Johann-Wolfgang Goethe Universität Frankfurt, Institut für Kernphysik Frankfurt
Place of publication:Frankfurt am Main
Referee:Christoph BlumeORCiDGND, Tetyana GalatyukORCiDGND
Advisor:Christoph Blume, Julian Book
Document Type:Master's Thesis
Year of Completion:2017
Year of first Publication:2017
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Granting Institution:Johann Wolfgang Goethe-Universität
Date of final exam:2017/03/23
Release Date:2022/11/17
Page Number:93
Last Page:93
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht