The Belle II Silicon Vertex Detector: Performance and Operational Experience in the First Year of Data Taking

In spring 2019 the Belle II experiment at the high-luminosity SuperKEKB e+e− collider (KEK, Japan) has resumed operation after the installation of the new vertex detector. In the first period of operation SuperKEKB has already reached the record luminosity of 2.4 × 1034 cm−2 s−1 which will be increased by about a factor 30 in the coming years. Two inner layers of DEPFET-based pixels and four layers of double-sided silicon strip detectors (Silicon Vertex Detector, SVD) make up this new vertex detector, designed to meet the stringent physics requirements as well as to cope with the high beam background conditions. Since the beginning of data taking, the SVD has been functioning with a very reliable and stable operation and excellent detector performance. The first evidence of radiation effects in the SVD have been observed, which are at the expected level and not affecting performance. This paper will review the performance achieved by the SVD and the lessons learned in the first year of operation that continued even during the COVID-19 pandemic.