Volume 544 - 43rd International Conference on High Energy Physics (ICHEP2026) - Session Operation, Performance and Upgrade of Present Detectors
Operational experience and performance of the Silicon Vertex Detector during Run 2 of Belle II
T. Shimasaki
Full text: Not available
Abstract
Belle II Run 1 began in March 2019 and was followed by Long Shutdown 1, which lasted from June 2022 to January 2024.
Run 2 began in January 2024.
During Run 2, the accelerator has been operated at higher beam currents than in Run 1, exposing the Vertex Detector (VXD) to higher radiation levels.
Despite this, the Silicon Vertex Detector (SVD), which forms the outer four layers of the VXD, has demonstrated robust performance even under such a harsh radiation environment.
No serious damage, significant increase in noise, or significant change in the full-depletion voltage has been observed.
The SVD continues to show performance comparable to that in Run 1 in terms of charge collection and track-position resolution.

The present SVD occupancy remains low, at approximately 1.2% even in the region closest to the interaction point.
However, with the expected increase in luminosity and planned upgrades to the accelerator and interaction region, the occupancy may increase to a level at which the tracking performance would be significantly degraded.
To suppress beam backgrounds more efficiently, the reconstruction procedure has been improved by exploiting the excellent hit-time resolution of the SVD.

In this paper, we first review the Belle II experiment and the SVD, and then report on the operational experience during Run 2
as well as recent software and firmware developments aimed at maintaining robust SVD performance at higher luminosities.
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