Belle II Vertex Detector Performance

Bilka, T.

doi:10.22323/1.373.0001

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…Impact parameter resolution has been studied using a small data sample collected in May 2019 [10,11]. The resolutions were estimated by half of the symmetric range around the median with 68% coverage of a distribution.…”

Section: Impact Parameter Resolutionmentioning

confidence: 99%

Operational Experience and Performance of the Belle II Pixel Detector

Liu

Abudinén

Ackermann

et al. 2021

Proceedings of the 29th International Workshop on Vertex Detectors (VERTEX2020)

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This article is published by the Physical Society of Japan under the terms of the Creative Commons Attribution 4.0 License. Any further distribution of this workThe Belle II experiment at the super KEK B factory (SuperKEKB) started its physics operation with the full detector setup in March 2019, and it aims at collecting 50 ab −1 of e + e − collision data. The vertex detector (VXD) of Belle II contains a 4-layer silicon vertex detector (SVD) using double sided silicon strips and an inner 2-layer pixel detector (PXD) that is based on the depleted P-channel Field Effect Transistor (DEPFET) technology. The signal generation and amplification are combined in pixels with a minimum pitch of 55 µm × 50 µm. The sensors are thinned down to 75 µm, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. This approach led to a material budget of around 0.21% X 0 per layer including the cooling structure in the acceptance region. The PXD has an integration time of around 20 µs, a signal-tonoise ratio of around 50 and a detecting efficiency of better than 99%. Its two layers are arranged at the radii of 14 mm and 22 mm around the interaction point, and an impact parameter resolution of better than 15 µm has been achieved. Due to its close proximity to the beam line and its sensitivity to few-keV photons, the PXD also plays an important role in background studies.

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Section: Impact Parameter Resolutionmentioning

confidence: 99%

Operational Experience and Performance of the Belle II Pixel Detector

Liu

Abudinén

Ackermann

et al. 2021

Proceedings of the 29th International Workshop on Vertex Detectors (VERTEX2020)

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“…The reasons are delays in the process of glueing modules to layers. Initial results demonstrate module hit efficiencies above 98 % [54] and even with the reduced PXD, a transverse impact parameter resolution of 14.1(1) µm [39].…”

Section: The Belle II Pixel Detectormentioning

confidence: 99%

“…The obtained intrinsic spatial resolutions are in the order of 10 µm for d 0 and 13 µm for z 0 . The measured overall impact parameter resolution in d 0 has been reported to be 14.1 ± 0.1 µm based on the first available data [39]. Note that the computation of this value follows a different approach than the simulation.…”

Section: The Importance Of Vertex Resolutionmentioning

confidence: 99%

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Characterisation, optimisation and performance studies of pixel vertex detector modules for the Belle II experiment

Wieduwilt¹

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The Standard Model of particle physics is very successful in describing the fundamental particles and their interactions. Still, some questions regarding the details and input parameters of the theory, as well as regarding to date unsatisfactorily described phenomena are to be answered. Today's high-energy physics experiments probe this new physics. The Belle II experiment at the SuperKEKB e + e − -collider in Japan explores the precision frontier, measuring the properties of particle interactions at great detail. The precise and abundant study of decays of B-mesons is a particularly good window to seek answers to the open questions of electro-weak interactions. Precise measurements in Belle II are possible in particular with a silicon pixel detector located very close to the interaction region of the electrons and positrons. The pixel detector is based on the depleted field-effect transistor (DEPFET) technology, which is employed for the first time in a high-energy physics experiment.Modules for the Belle II pixel detector were produced. A characterisation and optimisation procedure for these modules was developed in the scope of this thesis. A number of 17 modules have been processed according to this program, and the qualification criteria for the installation in Belle II have been determined. In addition, the performance of detector modules has been evaluated in beam tests. It is demonstrated that the optimisation procedure yields consistent characteristics among the tested modules. Signal-to-noise ratios of 20 to 40 are achieved at an in-pixel amplification factor of about 500 pA/electron in the DEPFET cell. The intrinsic spatial resolution is measured to be in the order of 10 µm, depending on pixel pitch and incidence angles, with a hit efficiency of 99.6 %. The module performance is in good agreement with the design goals and the requirements for the Belle II pixel detector are met. Characterisation, optimisation and performance studies of pixel vertex detector modules for the Belle II experiment Zusammenfassung Das Standardmodell der Elementarteilchenphysik beschreibt sehr erfolgreich die fundamentalen Teilchen und ihre Wechselwirkungen. Dennoch bleiben einige Fragen bezüglich Details und Parameter der Theorie bislang unbeantwortet. Einige Phänomene, wie beispielsweise Dunkle Materie oder Quantengravitation, sind bisher nicht, oder nur unzureichend beschrieben. Heutige Hochenergiephysikexperimente erforschen diese neue Physik in Teilchenkollisionen. Das Belle II-Experiment am SuperKEKB e + e − -Beschleuniger in Japan untersucht die Eigenschaften von Teilchenwechselwirkungen mit höchster Präzision, um so die Grenzen der bisherigen Theorie zu erweitern und Parameter des Standardmodells genauer zu bestimmen. Die genaue Beobachtung von zahlreichen Zerfällen von B-Mesonen ermöglicht es, offene Fragen der elektroschwachen Wechselwirkung zu beantworten. Präzisionsmessungen im Belle II Experiment werden insbesondere durch einen Silizium-Pixeldetektor ermöglicht, der sehr nah am Wechselwirkungspunkt der Teilchenko...

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