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.

Download Full-text

Installation of a Cosmic-Ray Trigger System to Commission the Belle II Experiment VerteX Detector with Cosmic Rays

Journal of Undergraduate Reports in Physics ◽

10.1063/10.0006341 ◽

2021 ◽

Vol 31 (1) ◽

pp. 100003

Author(s):

Ahmed Halawani ◽

Rachid Ayad ◽

Mohammed Albalawi ◽

Mansour Alatawi ◽

Abdulaziz Alatawi ◽

...

Keyword(s):

Cosmic Rays ◽

Cosmic Ray ◽

Trigger System ◽

Vertex Detector ◽

Belle Ii

Download Full-text

The Belle II experiment: Status and prospects

EPJ Web of Conferences ◽

10.1051/epjconf/201819200028 ◽

2018 ◽

Vol 192 ◽

pp. 00028

Author(s):

Alberto Martini

Keyword(s):

High Precision ◽

Second Generation ◽

New Physics ◽

Precision Measurements ◽

Matrix Elements ◽

Vertex Detector ◽

Ckm Matrix ◽

Belle Ii ◽

Belle Experiment ◽

Flavour Physics

This article aims to describe the Belle II experiment, its status and physics prospects for the next several years. Belle II is situated in Japan, at the KEK laboratory and it is the upgraded version of the Belle experiment. It uses a new collider named SuperKEKB, a second generation of B-factory based on the innovative Nano-Beam scheme technique, which is expected to collect an integrated luminosity of 50 ab-1. Using this amount of data, together with improved detector performances, it will be possible to provide important contributions about several flavour physics topics (i.e. CKM matrix elements, FCNC processes, quarkonium states etc..) through high precision measurements. The main aim of Belle II is to investigate new physics scenarios and validate highly suppressed SM predictions. The experiment is almost completely assembled; it already took the first data without the vertex detector installed while the data taking will start in February 2019.

Download Full-text

Alignment and Calibration of the Belle II Detector

EPJ Web of Conferences ◽

10.1051/epjconf/201921401040 ◽

2019 ◽

Vol 214 ◽

pp. 01040

Author(s):

Tadeáၡ Bilka ◽

Kirill Chilikin ◽

David Dossett ◽

Yinghui Guan ◽

Jakub Kandra ◽

...

Keyword(s):

Drift Chamber ◽

High Energy ◽

Beyond The Standard Model ◽

Vertex Detector ◽

Alignment Procedure ◽

Processing Power ◽

Electron Positron ◽

The Standard Model ◽

Belle Ii

In spring 2018 the SuperKEKB electron-positron collider at High Energy Accelerator Research Organization (KEK, Tsukuba, Japan) will deliver its first collisions to the Belle II experiment. The aim of Belle II is to collect a data sample 50 times larger than the previous generation of BFactories taking advantage of the unprecedented SuperKEKB design luminosity of 8×1035cm-2s-1. The Belle II detector will allow to conduct precise measurements in the harsh collider environment, probing for signs of physics beyond the standard model at the precision frontier. In order to deliver data suitable for physics analysis, the detector has to be properly calibrated on a regular basis. Among other calibrations the detector alignment plays a key role. For example, precise measurements of time dependent CP-violation rely on the accurate alignment of the new vertex detector, as well as on the determination of the beamspot position and size. To automate the calibration procedures and manage the large amount of data and processing power needed for detector calibration, a software framework has been developed which allows to define the complete workflow and to execute it on a computing cluster. The framework integrates the Millepede II algorithm to solve the large minimization problem emerging in the track-based alignment and calibration of the pixel and strip detector, the central drift chamber, and the muon system. The first collision data will allow to test and to further improve and tune the alignment and calibration procedures. Although the vertexing capabilities will be limited due to the installation of only a small slice of the full vertex detector, the commissioning phase will allow to test most of the alignment procedure features and to prepare for the full operation. We will present the results achieved during the first data taking, the experience gained and the plans for the first physics run with the full detector.

Download Full-text

Data quality monitors of vertex detectors at the start of the Belle II experiment

EPJ Web of Conferences ◽

10.1051/epjconf/202024501035 ◽

2020 ◽

Vol 245 ◽

pp. 01035

Author(s):

Peter Kodyš ◽

Jesus Abudinen ◽

Karlheinz Georg Ackermann ◽

Karol Mateusz Adamczyk ◽

Patrick Ahlburg ◽

...

Keyword(s):

Data Quality ◽

Quality Monitoring ◽

Software Framework ◽

Phase 2 ◽

Full Data ◽

Vertex Detector ◽

Belle Detector ◽

Electron Positron ◽

Belle Ii ◽

Positron Collisions

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.

Download Full-text

The Software Framework of the Belle II Silicon Vertex Detector and its Development for the 2016 Test-Beam at DESY

10.22323/1.287.0060 ◽

2017 ◽

Author(s):

Giacomo Caria ◽

K. Adamczyk ◽

H. Aihara ◽

C. Angelini ◽

T. Aziz ◽

...

Keyword(s):

Software Framework ◽

Test Beam ◽

Vertex Detector ◽

Belle Ii

Download Full-text

Track Fitting for the Belle II Experiment

EPJ Web of Conferences ◽

10.1051/epjconf/201921402039 ◽

2019 ◽

Vol 214 ◽

pp. 02039 ◽

Cited By ~ 1

Author(s):

Stefano Spataro

Keyword(s):

Magnetic Field ◽

Pattern Recognition ◽

Parameter Estimation ◽

Tracking System ◽

Center Of Mass ◽

Drift Chamber ◽

Pixel Detectors ◽

Track Parameter ◽

Belle Ii ◽

Fitting In

The Belle II experiment has started to take data in 2018, studying e+e- collisions at the KEK facility in Tsukuba (Japan), in a center of mass energy range of the Bottomonium states. The tracking system includes a combination of hit measurements coming from the vertex detector, made of pixel detectors and double-sided silicon strip detectors, and acentral drift chamber, inside a solenoid of 1.5 T magnetic field. Once the pattern recognition routines have identified the track candidates, hit measurements are fitted taking into account the different information coming from different detectors, the energy loss in the materials and the inhomogeneity of the magnetic field. Track fitting is performed by the generic track-fitting software GENFIT, which includes a Kalman filter improved by a deterministic annealing filter, in order to reject outlier hits coming from not correctly associated hits by the pattern recognition. Several mass hypotheses are used in the fit, in order to achieve the best track parameter estimation for each particle kind. This article presents the design of the track fitting in the Belle II software, showing results in terms of track parameter estimation as well as computing performances.

Download Full-text

Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

EPJ Web of Conferences ◽

10.1051/epjconf/201920901007 ◽

2019 ◽

Vol 209 ◽

pp. 01007

Author(s):

Francesco Nozzoli

Keyword(s):

Electron Flux ◽

Space Station ◽

Cosmic Ray ◽

High Energy ◽

Precision Measurements ◽

High Energy Electrons ◽

Electrons And Positrons ◽

Positron Flux ◽

Rigidity Dependence ◽

Alpha Magnetic Spectrometer

Precision measurements by AMS of the fluxes of cosmic ray positrons, electrons, antiprotons, protons as well as their rations reveal several unexpected and intriguing features. The presented measurements extend the energy range of the previous observations with much increased precision. The new results show that the behavior of positron flux at around 300 GeV is consistent with a new source that produce equal amount of high energy electrons and positrons. In addition, in the absolute rigidity range 60–500 GV, the antiproton, proton, and positron fluxes are found to have nearly identical rigidity dependence and the electron flux exhibits different rigidity dependence.

Download Full-text

Can the Local Bubble explain the radio background?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab131 ◽

2021 ◽

Vol 502 (2) ◽

pp. 2807-2814

Author(s):

Martin G H Krause ◽

Martin J Hardcastle

Keyword(s):

Magnetic Field ◽

Energy Density ◽

Radio Emission ◽

Magnetic Energy ◽

Cosmic Ray ◽

Observational Constraints ◽

Local Bubble ◽

Magnetic Energy Density ◽

Magnetic Field Model ◽

Radio Background

ABSTRACT The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can currently account for this finding. We use the locally measured cosmic ray electron population, demodulated for effects of the Solar wind, and other observational constraints combined with a turbulent magnetic field model to predict the radio synchrotron emission for the Local Bubble. We find that the spectral index of the modelled radio emission is roughly consistent with the radio background. Our model can approximately reproduce the observed antenna temperatures for a mean magnetic field strength B between 3 and 5 nT. We argue that this would not violate observational constraints from pulsar measurements. However, the curvature in the predicted spectrum would mean that other, so far unknown sources would have to contribute below 100 MHz. Also, the magnetic energy density would then dominate over thermal and cosmic ray electron energy density, likely causing an inverse magnetic cascade with large variations of the radio emission in different sky directions as well as high polarization. We argue that this disagrees with several observations and thus that the magnetic field is probably much lower, quite possibly limited by equipartition with the energy density in relativistic or thermal particles (B = 0.2−0.6 nT). In the latter case, we predict a contribution of the Local Bubble to the unexplained radio background at most at the per cent level.

Download Full-text