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Description
The Belle II vertex detector consists of an inner two-layer pixel detector (PXD2) and an outer four-layer double-sided silicon-strip detector (SVD).
In 2024 the Belle II experiment resumed data taking after its Long Shutdown 1, which was required to install PXD2 and upgrade components of the SuperKEKB accelerator. We describe the challenges of this upgrade and report on the operational experience during the subsequent data taking. With new data, the SVD confirmed high hit efficiency, large signal-to-noise and good cluster-position resolution. Operation of PXD2 has been limited because it had to be turned off as a precautionary measure for much of the data taking. Once the stability of the SuperKEKB beams improve the PXD will resume operation. Details of the performance of SVD and PXD2 will be shown. In addition, for the SVD, we present studies that show a moderate radiation-induced increase in sensor current and strip noise. However, such damage will not degrade the performance during the lifespan of the detector.