Freiburg 1999 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 45: Instrumentation und Anwendungen V

HK 45.8: Gruppenbericht

Mittwoch, 24. März 1999, 17:45–18:00, F

Neural network based π⁰-identification with the BaBar-calorimeter — •Helmut Schmücker — Ruhr-Universität Bochum

The primary physics goal of the BaBar-experiment is the study of CP-violation in the B⁰B⁰ system. The investigation of the rare CP-violating decays B⁰—→π⁰π⁰ requires a very efficient and pure identification of π⁰-mesons in an energy range from 20MeV up to 5GeV. In the high energy region the showers of the two photons emerging from the pion decay overlap in the segmented CsI(Tl)-calorimeter resulting in clusters of crystal energy deposits with one or two local maxima. The lateral energy distribution of these clusters is expanded in terms of the orthonormal Zernike functions. The Zernike moments, which hold the information about the azimuthal and radial energy distribution in the cluster, are used as input for a supervised trained feed-forward neural network. This talk discusses how a higher pion-identification efficiency at high energies can be achieved in comparison to conventional methods.