First results of the Belle II Silicon Vertex Detector readout system

Abstract

At the heart of the Belle II experiment at KEK (Japan), there will be a Vertex Detector (VXD) composedof 2 layers of DEPFET pixels (PXD) and 4 layers of double-sided silicon strip detectors (SVD).The latter use the APV25 front-end chip — originally developed for CMS — which is reading out the inner part of the SVD sensors through the Origami chip-on-sensor concept, including a state-of-the-art two-phase CO2 cooling. The whole system (including the full DAQ chain) was successfully tested in a beam at DESY in January 2014 and first results are presented here.