9 research outputs found
Upgrade of Online Storage and Express-Reconstruction System for the Belle II Experiment
International audienceThe Belle II experiment started to take data of electron–positron collisions provided by the SuperKEKB accelerator, with all subdetectors from March 2019. The collected data are selected by a software-based high-level trigger (HLT) system and stored on online storage. After storing the data, the online storage sends the data to an express-reconstruction system for semireal-time data quality monitoring (DQM) and event display. The HLT system is built on the ZeroMQ networking library, but the online storage and express-reconstruction system are built on the ring buffer and transmission control protocol/internet protocol (TCP/IP) socket-based framework. To improve stability and future maintainability, we develop a new online storage and express-reconstruction system using the ZeroMQ library. The new systems have a few additional improvements. First, the online storage supports the ROOT output file format with compression. This reduces the online file size, necessary network bandwidth for the online-to-offline file transfer, and offline computing resource usage. Second, two types of express-reconstruction systems are prepared based on the HLT results: for randomly sampled data and for physics-flagged data by the HLT system. The separate express-reconstruction system can process a larger number of statistics of physics-flagged events
Data quality monitors of vertex detectors at the start of the Belle II experiment
The Belle II experiment features a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric e+e− collider at KEK in Tsukuba, Japan. The accelerator completed its first phase of commissioning in 2016, and the Belle II detector saw its first electron-positron collisions in April 2018. Belle II features a newly designed silicon vertex detector based on double-sided strip layers and DEPFET pixel layers. A subset of the vertex detector was operated in 2018 to determine background conditions (Phase 2 operation). The collaboration completed full detector installation in January 2019, and the experiment started full data taking.
This paper will report on the final arrangement of the silicon vertex detector part of Belle II with a focus on online monitoring of detector conditions and data quality, on the design and use of diagnostic and reference plots, and on integration with the software framework of Belle II. Data quality monitoring plots will be discussed with a focus on simulation and acquired cosmic and collision data
Alignment for the first precision measurements at Belle II
International audienceOn March 25th 2019, the Belle II detector recorded the first collisions delivered by the SuperKEKB accelerator. This marked the beginning of the physics run with vertex detector.The vertex detector was aligned initially with cosmic ray tracks without magnetic field simultaneously with the drift chamber. The alignment method is based on Millepede II and the General Broken Lines track model and includes also the muon system or primary vertex position alignment. To control weak modes, we employ sensitive validation tools and various track samples can be used as alignment input, from straight cosmic tracks to mass-constrained decays.With increasing luminosity and experience, the alignment is approaching the target performance, crucial for the first physics analyses in the era of Super-BFactories. We will present the software framework for the detector calibration and alignment, the results from the first physics run and the prospects in view of the experience with the first data
Alignment for the first precision measurements at Belle II
On March 25th 2019, the Belle II detector recorded the first collisions delivered by the SuperKEKB accelerator. This marked the beginning of the physics run with vertex detector.
The vertex detector was aligned initially with cosmic ray tracks without magnetic field simultaneously with the drift chamber. The alignment method is based on Millepede II and the General Broken Lines track model and includes also the muon system or primary vertex position alignment. To control weak modes, we employ sensitive validation tools and various track samples can be used as alignment input, from straight cosmic tracks to mass-constrained decays.
With increasing luminosity and experience, the alignment is approaching the target performance, crucial for the first physics analyses in the era of Super-BFactories. We will present the software framework for the detector calibration and alignment, the results from the first physics run and the prospects in view of the experience with the first data
Data quality monitors of vertex detectors at the start of the Belle II experiment
The Belle II experiment features a substantial upgrade of the Belle detector and will operate at the SuperKEKB energy-asymmetric e+e− collider at KEK in Tsukuba, Japan. The accelerator completed its first phase of commissioning in 2016, and the Belle II detector saw its first electron-positron collisions in April 2018. Belle II features a newly designed silicon vertex detector based on double-sided strip layers and DEPFET pixel layers. A subset of the vertex detector was operated in 2018 to determine background conditions (Phase 2 operation). The collaboration completed full detector installation in January 2019, and the experiment started full data taking.
This paper will report on the final arrangement of the silicon vertex detector part of Belle II with a focus on online monitoring of detector conditions and data quality, on the design and use of diagnostic and reference plots, and on integration with the software framework of Belle II. Data quality monitoring plots will be discussed with a focus on simulation and acquired cosmic and collision data
Measurement of the lifetime at Belle II
We report on a measurement of the lifetime using decays reconstructed in data collected by the Belle II experiment and corresponding to of integrated luminosity. The result, , agrees with recent measurements indicating that the is not the shortest-lived weakly decaying charmed baryon
Measurement of the lifetime at Belle II
We report on a measurement of the lifetime using decays reconstructed in data collected by the Belle II experiment and corresponding to of integrated luminosity. The result, , agrees with recent measurements indicating that the is not the shortest-lived weakly decaying charmed baryon
Measurement of the lifetime at Belle II
We report on a measurement of the lifetime using decays reconstructed in data collected by the Belle II experiment and corresponding to of integrated luminosity. The result, , agrees with recent measurements indicating that the is not the shortest-lived weakly decaying charmed baryon