Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 61: DAQ

T 61.9: Talk

Wednesday, March 11, 2015, 18:45–19:00, G.10.07 (HS 5)

Concept of the K_S⁰ Rescue System for the Belle II Pixel Detector — •Leonard Koch, Wolfgang Kühn, Sören Lange, and David Münchow for the Belle II collaboration — II. Physikalisches Institut, JLU Gießen

The Belle II experiment at KEK in Tsukuba, Japan will perform studies with B mesons with a factor 40 increased luminosity compared to its predecessor experiment, Belle. One of the main goals of Belle II is the search for physics beyond the Standard Model, for example in rare B meson decays described by loop diagrams. Detecting B mesons frequently involves the detection of K_S⁰ with its displaced decay vertices.

The innermost detector of Belle II is the Pixel Detector (PXD) with an expected occupancy of up to 3% due to high background. In order to reduce the data, only hits inside region-of-interests (ROIs) are read out. The ROIs are determined by extrapolation into the PXD region of tracks in the surrounding detectors, the Silicon Vertex Detector (SVD), and the outer detectors. Thus every PXD hit of a particle, which does not create a valid track in the track finder, and subsequently no ROI, will not be recorded. Frequently pions originating from a secondary vertex of a K_S⁰ decay do not create sufficient hits in the SVD. As a consequence, a significant amount of K_S⁰ mesons will be lost. In this contribution, we present a concept for the K_S⁰ - rescue system. Here, we perform online tracking using all of the PXD and SVD layers to find the tracks of these pions, to improve the K_S⁰ reconstruction efficiency.

This work is supported by the Bundesministerium für Bildung und Forschung under grant number 05H12RG8.