Jarek Wiechczynski

05 December 2023

Abstract: The Belle II experiment operating on the asymmetric e+ e- SuperKEKB collider, located in Tsukuba (Japan), has been collecting data since March 2019. Its excellent vertexing abilities are provided by Vertex Detector (VXD), part of which is Silicon Vertex Detector (SVD) playing a crucial role in the tracking close to the interaction point. SVD operates very successfully and efficiently over the whole period of data taking so far. In this article we briefly discuss its purpose, structure and basic description of the front-end electronics. The main variables related to the SVD performance (Cluster Charge, Signal-to-Noise ratio, sensor efficiency, spatial and time resolution) are presented. We elaborate on the challenges concerning the increase of the SuperKEKB luminosity and related impact on the SVD performance in the high background environment. The quick overview of the radiation campaign is presented to show the predicted behaviour of the sensors subjected to the high radiation, whose level is constantly monitored. We also discuss the ongoing effort in the software development to account for the expected high occupancy in the SVD detector in the future. In particular, the utilization of the SVD hit time information is presented as a very important quantity to suppress off-time background hits and tracks. Finally, the Long Shutdown 1 is briefly overviewed, during which the major upgrade of the Pixel Detector (PXD) has been successfully done. Resume of the beam operation is expected in early 2024.

Keyword(s): Belle II ; Silicon strip detector ; Vertex detector ; Tracking detector