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T: Fachverband Teilchenphysik
T 70: Halbleiterdetektoren: Belle II
T 70.4: Vortrag
Mittwoch, 29. Februar 2012, 17:35–17:50, ZHG 005
Estimation of the Two-photon background in the Belle II Pixel Vertex Detector — •Elena Nedelkovska, Christian Kiesling, and Susanne Koblitz — Max-Planck Intitut fuer Physik, Muenchen
The current KEKB accelerator will be upgraded to SuperKEKB, with a design luminosity of 0.8 × 1036 cm−2s−1. The present Belle detector will also be upgraded to Belle II, containing an entirely new inner part, a pixel vertex detector (PXD). The PXD will be placed very close to the beam-pipe and has to stand very hostile background conditions. An important background source is the luminosity-related background, such as γγ → e+e−, where very low energy O (5 MeV) electrons and positrons are emitted. These particles will reach mostly the inner layers of the Belle II Si system. Such processes have not been measured so far. In order to determine whether this QED process might be a dominant source of background, three dedicated experiments were performed at KEK. The results of these experiments will be presented, as well as their relevance for the PXD. The measurements are compared to Monte-Carlo simulations and based on this the estimated two-photon QED background and therefore the expected occupancy in the innermost PXD layer will be discussed.