Silicon Vertex Detector of the Belle II Experiment
Abstract
The silicon vertex detector (SVD) is installed at the heart of the Belle II experiment, taking data at the high-luminosity -Factory SuperKEKB since 2019. The detector has shown a stable and above-99\% hit efficiency, with a large signal-to-noise in all sensors since the beginning of data taking. Cluster position and time resolution have been measured with 2020 and 2022 data and show excellent performance and stability. The effect of radiation damage is visible, but not affecting the performance. As the luminosity increases, higher machine backgrounds are expected and the excellent hit-time information in SVD can be exploited for background rejection. In particular, we have recently developed a novel procedure to select hits by grouping them event-by-event based on their time. This new procedure allows a significant reduction of the fake rate, while preserving the tracking efficiency, and it has therefore replaced the previous cut-based procedure. We have developed a method that uses the SVD hits to estimate the track time (previously unavailable) and the collision time. It has a similar precision to the estimate based on the drift chamber but its execution time is three orders of magnitude smaller, allowing a faster online reconstruction that is crucial in a high luminosity regime. The track time is a powerful information provided to analysis that allows, together with the above-mention grouping selection, to raise the occupancy limit above that expected at nominal luminosity, leaving room for a safety factor. Finally, in June 2022 the data taking of the Belle II experiment was stopped to install a new two-layer DEPFET detector (PXD) and upgrade components of the accelerator. The whole silicon tracker (PXD+SVD) has been extracted from Belle II, the new PXD installed, the detector closed and commissioned. We briefly describe the SVD results of this upgrade.
Keywords
Cite
@article{arxiv.2312.06501,
title = {Silicon Vertex Detector of the Belle II Experiment},
author = {S. Mondal and K. Adamczyk and L. Aggarwal and H. Aihara and T. Aziz and S. Bacher and S. Bahinipati and G. Batignani and J. Baudot and P. K. Behera and S. Bettarini and T. Bilka and A. Bozek and F. Buchsteiner and G. Casarosa and L. Corona and S. B. Das and G. Dujany and C. Finck and F. Forti and M. Friedl and A. Gabrielli and B. Gobbo and S. Halder and K. Hara and S. Hazra and T. Higuchi and C. Irmler and A. Ishikawa and Y. Jin and M. Kaleta and A. B. Kaliyar and J. Kandra and K. H. Kang and P. Kodyš and T. Kohriki and R. Kumar and K. Lalwani and K. Lautenbach and R. Leboucher and S. C. Lee and J. Libby and L. Martel and L. Massaccesi and G. B. Mohanty and K. R. Nakamura and Z. Natkaniec and Y. Onuki and F. Otani and A. PaladinoA and E. Paoloni and H. Park and L. Polat and K. K. Rao and I. Ripp-Baudot and G. Rizzo and Y. Sato and C. Schwanda and J. Serrano and T. Shimasaki and J. Suzuki and S. Tanaka and H. Tanigawa and F. Tenchini and R. Thalmeier and R. Tiwary and T. Tsuboyama and Y. Uematsu and L. Vitale and Z. Wang and J. Webb and O. Werbycka and J. Wiechczynski and H. Yin and L. Zani},
journal= {arXiv preprint arXiv:2312.06501},
year = {2024}
}
Comments
16$^{\text{th}}$ Topical Seminar on Innovative Particle and Radiation Detectors (IPRD23) 25--29 September 2023 Siena, Italy