9 research outputs found
Status of the BELLE II Pixel Detector
The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting collision data since March 2019. Operating at a record-breaking luminosity of up to , data corresponding to has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of . A high gain and a high signal-to-noise ratio allow thinning the pixels to while retaining a high pixel hit efficiency of about . As a consequence, also the material budget of the full detector is kept low at per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital
Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023
Dreidimensionale Observierung atmosphärischer Prozesse in Städten – 3DOSchlussbericht des Verbundvorhabens 3DOThree-dimensional observation and modeling of atmospheric processes in cities – 3DOfinal report for joint project 3DO
Ziel des BMBF-Programms 'Stadtklima im Wandel' war die Entwicklung, Validierung und Anwendung eines gebäudeauflösenden Stadtklimamodells für ganze Städte. Das Verbundprojekt 3DO übernahm die dem Modul B zugeordneten Forschungsaufgaben: Aufbereitung vorhandener Daten aus der Langzeitbeobachtung (LTO), Aufbau neuer Messstationen, Gewinnung neuer dreidimensionaler atmosphärischer Daten und die Entwicklung neuer Konzepte z.B. zur Modellevaluation. Untersucht wurden der Aufbau der atmosphärischen Grenzschicht, die Charakteristik der meteorologischen Parameter und deren Einfluss auf das thermische Empfinden des Menschen. Ein einheitlicher [UC]2-Datenstandard sowie Analysewerkzeuge wurden entwickelt und in ein Datenmanagementsystem und eine Wissensplattform für den modulübergreifenden Austausch integriert.Aim of the BMBF-Programme 'Urban Climate under Change' was development, validation and application of a building-resolving urban climate model for entire cities. The joint project 3DO took over the research tasks assigned to module B: Preparation of existing data from long-term observation (LTO), deployment of new measuring stations, acquisition of new three-dimensional atmospheric data and new concepts, e.g. for model evaluation. The structure of the atmospheric boundary layer, characteristics of meteorological parameters and their influence on the thermal sensation of humans were investigated. A uniform [UC]2 data standard as well as analysis tools were developed and integrated into a data management system and a knowledge base for cross-module exchange
Dreidimensionale Observierung atmosphärischer Prozesse in Städten – 3DOSchlussbericht des Verbundvorhabens 3DOThree-dimensional observation and modeling of atmospheric processes in cities – 3DOfinal report for joint project 3DO
Ziel des BMBF-Programms 'Stadtklima im Wandel' war die Entwicklung, Validierung und Anwendung eines gebäudeauflösenden Stadtklimamodells für ganze Städte. Das Verbundprojekt 3DO übernahm die dem Modul B zugeordneten Forschungsaufgaben: Aufbereitung vorhandener Daten aus der Langzeitbeobachtung (LTO), Aufbau neuer Messstationen, Gewinnung neuer dreidimensionaler atmosphärischer Daten und die Entwicklung neuer Konzepte z.B. zur Modellevaluation. Untersucht wurden der Aufbau der atmosphärischen Grenzschicht, die Charakteristik der meteorologischen Parameter und deren Einfluss auf das thermische Empfinden des Menschen. Ein einheitlicher [UC]2-Datenstandard sowie Analysewerkzeuge wurden entwickelt und in ein Datenmanagementsystem und eine Wissensplattform für den modulübergreifenden Austausch integriert.Aim of the BMBF-Programme 'Urban Climate under Change' was development, validation and application of a building-resolving urban climate model for entire cities. The joint project 3DO took over the research tasks assigned to module B: Preparation of existing data from long-term observation (LTO), deployment of new measuring stations, acquisition of new three-dimensional atmospheric data and new concepts, e.g. for model evaluation. The structure of the atmospheric boundary layer, characteristics of meteorological parameters and their influence on the thermal sensation of humans were investigated. A uniform [UC]2 data standard as well as analysis tools were developed and integrated into a data management system and a knowledge base for cross-module exchange
Measurements of Beam Backgrounds in SuperKEKB Phase 2
The high design luminosity of the SuperKEKB electron-positron collider will result in challenging levels of beam-induced backgro unds in the interaction region. Understanding and mitigating these backgrounds is critical to the success of the Belle~II experi ment. We report on the first background measurements performed after roll-in of the Belle II detector, a period known as SuperKE KB Phase 2, utilizing both the BEAST II system of dedicated background detectors and the Belle II detector itself. We also repor t on first revisions to the background simulation made in response to our findings. Backgrounds measured include contributions f rom synchrotron radiation, beam-gas, Touschek, and injection backgrounds. At the end of Phase 2, single-beam backgrounds origina ting from the 4 GeV positron Low Energy Ring (LER) agree reasonably well with simulation, while backgrounds from the 7 GeV elect ron High Energy Ring (HER) are approximately one order of magnitude higher than simulation. We extrapolate these backgrounds for ward and conclude it is safe to install the Belle II vertex detector
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