Study of improved K_S^0 detection for the Belle II Detector

Sumitted to PubDB: 2016-10-13

Category: Master Thesis, Visibility: Public

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Authors	Leonard Koch, Wolfgang Kuehn
Non-Belle II authors	Sören Lange
Date	Jan. 1, 2015
Belle II Number	BELLE2-MTHESIS-2016-006
Abstract	In this work, an online tracking algorithm is developed and evaluated focusing on the reconstruction of charged pions from displaced vertices, the characteristic decay topology of K_s^0 mesons. All six VXD layers are used. The algorithm, which may be used on the FPGA-based PXD DAQ system, is based on the fast Hough transform applied to the hits mapped onto the conformal plane. The amount of background is reduced by a two stage neural network filtering system. Applied to data from a simulation of 10 000 typical Belle II events, the algorithm is adjusted to a fake rate of 90% being considered as tolerable, resulting in a pion reconstruction efficiency of 81.4 %. An alternative setup has a fake rate of 50 % and an efficiency of 63.6 %. The gained K_S^0 reconstruction efficiencies by the additional employment of the algorithm developed in this work are 5.0 % and 1.4 %, respectively, compared to the performance of the existing track finders.
Conference	Giessen