The DMAPS upgrade of the Belle II vertex detector Babeluk, M.; Barbero, M.; Baudot, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2024, Letnik:
1064
Journal Article
Recenzirano
The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028.
One ...proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk).
This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development.
The OBELIX chip for the Belle II VTX upgrade Babeluk, M.; Auguste, D.; Barbero, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2024, Letnik:
1067
Journal Article
Recenzirano
The OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) is currently developed for the upgrade of the vertex detector of the Belle II experiment located at Tsukuba/Japan. The pixel matrix of ...OBELIX is inherited from the TJ-Monopix2 chip, but the periphery includes additional features to improve performance and allow the integration into a larger detector system. The new features include a trigger unit to process trigger signals, a precision timing module and a possibility to transmit low granularity hit information with low latency to contribute to the Belle II trigger. Additionally, low dropout voltage regulators and an ADC to monitor power consumption and substrate temperature is developed. This paper will focus on the trigger contribution capabilities of the OBELIX chip.
In this paper we explore the effect of δ-ray emission and fluctuations in the signal deposition on the detection of charged particles in silicon-based detectors. We show that these two effects ...ultimately limit the resolution that can be achieved by interpolation of the signal in finely segmented position-sensitive solid-state devices.
SuperKEKB, the next generation B factory, has been constructed in Japan as an upgrade of KEKB. This brand new e+ e- collider is expected to deliver a very large data set for the Belle II experiment, ...which will be 50 times larger than the previous Belle sample. Both the triggered physics event rate and the background event rate will be increased by at least 10 times than the previous ones, and will create a challenging data taking environment for the Belle II detector. The software system of the Belle II experiment is designed to execute this ambitious plan. A full detector simulation library, which is a part of the Belle II software system, is created based on Geant4 and has been tested thoroughly. Recently the library has been upgraded with Geant4 version 10.1. The library is behaving as expected and it is utilized actively in producing Monte Carlo data sets for various studies. In this paper, we will explain the structure of the simulation library and the various interfaces to other packages including geometry and beam background simulation.
The paper is based on the data of the 2009 DEPFET beam test at CERN SPS. The beam test used beams of pions and electrons with energies between 40 and 120
GeV, and the sensors tested were prototypes ...with thickness of
450
μ
m
and pixel pitch between 20 and
32
μ
m
. Intrinsic resolutions of the detectors are calculated by disentangling the contributions of measurement errors and multiple scattering in tracking residuals. Properties of the intrinsic resolution estimates and factors that influence them are discussed. For the DEPFET detectors in the beam test, the calculation yields intrinsic resolutions of
≈
1
μ
m
, with a typical accuracy of
0.1
μ
m
. Bias scan, angle scan, and energy scan are used as example studies to show that the intrinsic resolutions are a useful tool in studies of detector properties. With sufficiently precise telescopes, detailed resolution maps can be constructed and used to study and optimize detector performance.
A neural network for beam background decomposition in Belle II at SuperKEKB Schwenker, B.; Herzberg, L.; Buch, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
April 2023, 2023-04-00, 2023-04-01, Letnik:
1049, Številka:
C
Journal Article
Recenzirano
Odprti dostop
We describe a neural network for predicting the background hit rate in the Belle II detector produced by the SuperKEKB electron–positron collider. The neural network, BGNet, learns to predict the ...individual contributions of different physical background sources, such as beam-gas scattering or continuous top-up injections into the collider, to Belle II sub-detector rates. The samples for learning are archived 1Hz time series of diagnostic variables from the SuperKEKB collider subsystems and measured hit rates of Belle II used as regression targets. We test the learned model by predicting detector hit rates on archived data from different run periods not used during training. We show that a feature attribution method can help interpret the source of changes in the background level over time.
Measurements of beam backgrounds in SuperKEKB Phase 2 Liptak, Z.; Paladino, A.; Santelj, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Letnik:
1040
Journal Article
Recenzirano
Odprti dostop
The high design luminosity of the SuperKEKB electron–positron collider will result in challenging levels of beam-induced backgrounds in the interaction region. Understanding and mitigating these ...backgrounds is critical to the success of the Belle II experiment. We report on the first background measurements performed after roll-in of the Belle II detector, a period known as SuperKEKB Phase 2, utilizing both the BEAST II system of dedicated background detectors and the Belle II detector itself. We also report on first revisions to the background simulation made in response to our findings. Backgrounds measured include contributions from synchrotron radiation, beam-gas, Touschek, and injection backgrounds. At the end of Phase 2, single-beam backgrounds originating from the 4 GeV positron Low Energy Ring (LER) agree reasonably well with simulation, while backgrounds from the 7 GeV electron High Energy Ring (HER) are approximately one order of magnitude higher than simulation. We extrapolate these backgrounds forward and conclude it is safe to install the Belle II vertex detector.
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