The Belle-II Pixel Vertex Detector at the SuperKEKB Flavor Factory
F. Simon, K. Ackermann, L. Andricek, C. Heller, C. Kiesling, A. Moll, H-G. Moser, J. Ninkovic, K. Prothmann, B. Reisert, R. Richter, M. Ritter, S. Rummel, A Wassatsch
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3 pages, 2 figures, submitted to the proceedings of the XXIV International Symposium on Lepton Photon Interactions at High Energies (Lepton Photon 09), Hamburg, Germany, August 2009
An upgraded asymmetric e+e- flavor factory, SuperKEKB, is planned at KEK. It will deliver a luminosity of 8 x 10^35 cm^-2 s^-1, allowing precision measurements in the flavor sector which can probe new physics well beyond the scales accessible to direct observation. The increased luminosity also requires upgrades of the Belle detector. Of critical importance here is a new silicon pixel vertex tracker, which will significantly improve the decay vertex resolution. This new detector will consist of two detector layers close to the interaction point, using DEPFET pixel sensors with 50 um thick silicon in the active area.
Belle II experiment at the SuperKEKB collider is a major upgrade of the Belle experiment at the KEKB asymmetric e^+e^- collider at the KEK. The experiment will focus on the search for new physics beyond the standard model via high precision measurement of heavy flavor decays and search for rare signals. In this talk, we present the status of the SuperKEKB collider and the Belle II detector.
The Belle II / SuperKEKB experiment is an $e^+e^-$ collider running at the $Υ(4S)$ resonance energy to produce B meson pairs. As an upgrade of the Belle / KEKB experiment, it will start physics data taking from 2018 and with $\sim 40$ times luminosity, its goal is to accumulate 50 $ab^{-1}$ of $e^+e^-$ collision data. Now the upgrade of the sub-detector systems is on-going in KEK. The physics program has a wide range of areas, including searches for direct CPV, Lepton Flavour Violation and dark matter. In this proceedings, we review the current upgrade status of Belle II and SuperKEKB and intr…
The Belle experiment, part of a broad-based search for new physics, is a collaboration of approximately 400 physicists from 55 institutions across four continents. The Belle detector is located at the KEKB accelerator in Tsukuba, Japan. The Belle detector was operated at the asymmetric electron-positron collider KEKB from 1999-2010. The detector accumulated more than 1/ab of integrated luminosity corresponding to more than 2 PB of data near 10 GeV center-of-mass energy. Recently, KEK has initiated a $400 million accelerator upgrade to be called SuperKEKB, designed to produce instantaneous and …
The Belle II detector is currently under construction at the SuperKEKB electron-positron high-luminosity collider, that will provide an instantaneous luminosity 40 times higher than that of KEKB. There- fore the Belle-II VerteX Detector (VXD) will operate in a very harsh environment. A radiation monitoring and beam abort system is needed to safely operate the VXD detector in these conditions. This system is based on 20 single crystal CVD diamond sensors placed in 20 key positions in the vicinity of the VXD and interaction region. In this contribution we describe the system design and we presen…
The Belle-II VerteX Detector (VXD) is a 6 layers silicon tracker device that will cope with an unprecedented luminosity of 8 x 10^35 cm-2 s-1 achievable by the new SuperKEKB e+e- collider, now under commissioning at the KEK laboratory (Tsukuba, Japan). A radiation monitoring and beam abort system has been developed based on single-crystal s-CVD diamond sensors. The sensors will be placed in 20 key positions in the vicinity of the interaction region. The severe space limitations require a remote readout of the sensors. In this contribution we present the system design, along with the sensor cha…
Currently the heavy flavour factory KEKB located at the KEK accelerator centre in Tsukuba, Japan, is being upgraded to the Super KEKB factory, aiming for a substantially higher luminosity of 8x10^35 cm^-2 s^-1. This by a factor of 40 increased luminosity requires significant modifications of the Belle detector. The vertex detector needs to be redesigned and, besides a four-layer silicon strip detector, a pixel detector based on the DEPFET technology will be installed closest to the interaction point. The requirements for this pixel detector, the DEPFET technology and the current status of the …
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 findin…
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has completed a commissioning run, achieved a peak luminosity of $5.5\times 10^{33}$ cm$^{-2}$s$^{-1}$, and Belle II has recorded a data sample of about 0.5 fb$^{-1}$. Main operation of SuperKEKB has started in March…
We describe the planned near-term and potential longer-term upgrades of the Belle II detector at the SuperKEKB electron-positron collider in Tsukuba, Japan. These upgrades will allow increasingly sensitive searches for possible new physics beyond the Standard Model in flavor, tau, electroweak and dark sector physics that are both complementary to and competitive with the LHC and other experiments. We encourage the instrumentation-frontier community to contribute and study upgrade ideas as part of the Snowmass process.
We designed, constructed and have been operating a system based on single-crystal synthetic diamond sensors, to monitor the beam losses at the interaction region of the SuperKEKB asymmetric-energy electron-positron collider. The system records the radiation dose-rates in positions close to the inner detectors of the Belle II experiment, and protects both the detector and accelerator components against destructive beam losses, by participating in the beam-abort system. It also provides complementary information for the dedicated studies of beam-related backgrounds. We describe the performance o…
The Belle II experiment at KEK in Japan has started real data taking from April 2018 to probe a New Physics beyond the Standard Model by measuring CP violation precisely and rare weak decays of heavy quark and lepton. The experiment is performed at the high luminosity SuperKEKB e^+ e^- collider with 80 x 10^34 cm^-2 s^-1 as an ultimate instantaneous luminosity. In order to develop and test an appropriate trigger algorithm under much higher luminosity and beam background environment than previous KEKB collider, a detail simulation study of the Belle II calorimeter trigger system is very crucial…
The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, will start physics data taking in 2018. It is planned to accumulate an e+ e- collision data set of 50 /ab, about 50 times larger than that of the earlier Belle experiment. The software library for the new detector will use GEANT4 for Monte Carlo simulation and is an entirely new software and reconstruction system based on modern computing tools. Examples of physics simulation including beam background overlays will be described.
High-precision flavor physics measurements play a complementary role to the direct searches for new physics by CMS and ATLAS experiments at LHC. Such measurements will be performed with the Belle II detector at the upgraded KEKB accelerator (SuperKEKB) in Japan. The physics potential with emphasis on the charm sector, current status and future prospects of the Belle II experiment are presented in these proceedings.
The Belle II experiment will be at the forefront of indirect searches for non-Standard-Model physics using billions of heavy quarks and $τ$ leptons produced in high-intensity 10 GeV electron-positron collisions from the SuperKEKB collider. The intense beams needed to achieve the required precisions are associated with high beam-background radiation that may damage the inner detectors. A dedicated radiation-monitoring and beam-abort system, based on artificial diamond sensors, ensures protection and safe data taking conditions. I briefly outline the system and illustrate the operational experie…
The Belle II experiment has been preparing for its first e+ e- collisions, scheduled in April 2018. With a target luminosity 40 times greater than the Belle experiment, the goal of Belle II is to open the door to a panorama of measurements in heavy flavour physics and much more. The initial beams and the commissioning of the SuperKEKB collider took place earlier in 2016. After completing most of the detector assembly and performing test runs with cosmic rays, the experiment is ready for initial collisions. Soon after in early 2019, data collection with the full Belle II detector will commence …
The Belle II experiment, which is situated at the interaction point of the SuperKEKB $e^+e^{-}$ collider at KEK, Tsukuba, Japan, is expected to collect data corresponding to an integrated luminosity of 50~ab$^{- 1}$. This data set will be sensitive to beyond-the-standard-model physics via precision measurements and searches for very rare decays. At its heart lies a six-layer vertex detector consisting of two layers of pixel detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). Precise vertexing as provided by this device is essential for measurements of time-depen…
The Belle II detector at the SuperKEKB accelerator has a level 1 trigger implemented in field-programmable gate arrays. Due to the high luminosity of the beam, a trigger that effectively rejects beam induced background is required. A three dimensional tracking algorithm for the level 1 trigger that uses the Belle II central drift chamber detector response is being developed to reduce the recorded beam background while having a high efficiency for physics of interest. In this paper, we describe the three dimensional track trigger that finds and fits track parameters which we developed.
The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, will start physics data taking in 2018 and will accumulate 50 ab$^{-1}$ of e$^{+}$e$^{-}$ collision data, about 50 times larger than the data set of the earlier Belle experiment. The computing requirements of Belle II are comparable to those of a run I high-p$_T$ LHC experiment. Computing will make full use of such grids in North America, Asia, Europe, and Australia, and high speed networking. Results of an initial MC simulation campaign with 3 ab$^{-1}$ equivalent luminosity will be described
The Belle II detector at the SuperKEKB accelerator complex is covering a wide range of exciting physics topics. To achieve the project's research goals, a substantial increase of the data sample to 50~ab$^{-1}$ is needed, and for that, the luminosity has to reach the ambitious goal of $6 \times 10^{35}$ cm$^{-2}$ s$^{-1}$. The progress towards the design luminosity is accompanied by research and development of the accelerator, detector components, operation methods, as well as their upgrades. In the present contribution, we will discuss the status and plans of the project, timescales for upgra…
A new muon and K_Long detector based on scintillators will be used for the endcap and inner barrel regions in the Belle II experiment, currently under construction. The increased luminosity of the e+e- SuperKEKB collider entails challenging detector requirements. We demonstrate that relatively inexpensive polystyrene scintillator stips with wave length shifting fibers ensure a sufficient light yield at the Silcon PhotoMultiplier (SiPM) photodetector, are robust and provide improved physics performance for the Belle II experiment compared to its predecessor, Belle.
Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV $e^+$ on 8 GeV $e^-$ asymmetric energy collider. We investigate the collision timing {\tip} and its $z$-coordinate along the beam axis {\zip} as a function of the position of the colliding bunch in a beam train. The various {\tip} and {\zip} behaviors observed by Belle are attributed to beam loading effects in the radio frequency cavities that accelerate the beams with a beam abort gap. We report these results in detail and discuss the prospects for the SuperKEKB collider.
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the …
Belle II is a $B$ factory experiment aiming to start physics data taking in 2017. It is currently being set up at the SuperKEKB accelerator at the KEK facility in Tsukuba (Japan), an asymmetric $e^+e^-$ collider which aims to achieve an unprecedented instantaneous luminosity of $8\cdot10^{35} \textrm{Hz}/\textrm{cm}^2$. This forty-fold increase over predecessor experiments is achieved by employing a novel nano-beam scheme. Originally developed for the now-defunct SuperB experiment, this scheme allows a significant increase in luminosity at only modest increases of beam currents. Challenges for…
The SuperKEKB accelerator in Tsukuba, Japan is providing e$^+$e$^-$ beams for the Belle II experiment since March 2019. To deal with the aimed peak luminosity being forty times higher than the one recorded at Belle, a pixel detector based on DEPFET technology has been installed. It features a long integration time of 20 $μ$s resulting in an expected data rate of 20 GByte/s (160 GBit/s) at a maximum occupancy of 3 %. To deal with this high amount of data, the data handling hub (DHH) has been developed. It contains all necessary functionality for the control and readout of the detector. In this …
The Belle II experiment, located at the SuperKEKB collider at the high-energy research facility KEK in Tsukuba, Japan, started operation in 2018. Compared to the predecessor experiment Belle, Belle II plans to increase the peak luminosity by a factor of about 40, by employing nano-beam technology in the interaction region. In particular the new, innermost sub-detector of Belle II - the Pixel Vertex Detector (PXD) - is in close proximity to the interaction point. This allows for the detection of particles, which do not leave a signal in the outer sub-detectors. Among these, Highly Ionizing Part…
The barrel-region particle identification detector is crucial for extending the physics reach of the Belle II experiment operating at the SuperKEKB accelerator. For this purpose, an imaging-Time-of-Propagation (iTOP) counter was developed, which is a new type of ring-imaging Cherenkov detector. The iTOP consists of 16 separate modules arranged azimuthally around the beam line. Each module consists of optical components fabricated from quartz (one mirror, one prism, and two bars), an array of micro-channel-plate photo-multiplier tubes (MCP-PMTs), and front-end electronics. The waveforms read ou…
The Belle detector operated at KEKb B-factory in 1999-2010 was one of the most remarkable experiments in the field of elementary particle physics of the last decades. The Belle successor, Belle II collaboration, is aimed to operate the Belle II detector at SuperKEKb factory at 40 times higher luminosity. Increased luminosity imposes new requirements on the detector elements: they have to survive at higher radiation levels, to operate at higher loads and at higher backgrounds. The Belle K_L and muon system based on the resistive plate chambers (RPC) technology worked well during all data taking…
The Belle II experiment will go into operation at the upgraded SuperKEKB collider in 2016. SuperKEKB is designed to deliver an instantaneous luminosity $\mathcal{L}=8\times10^{35}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$. The experiment will therefore have to cope with a much larger machine background than its predecessor Belle, in particular from events outside of the interaction region. We present the concept of a track trigger, based on a neural network approach, that is able to suppress a large fraction of this background by reconstructing the $z$ (longitudinal) position of the event vertex wit…
The Belle II detector at the SuperKEKB accelerator observed the first collisions in April this year. Until mid-summer, the first commissioning run uses a reduced version of the full vertex detector. Nevertheless, this phase is an excellent opportunity to improve and test the alignment and calibration procedures being prepared for the first physics runs starting in spring 2019. The procedure presented is based on Millepede II tool to solve the large minimization problem emerging in the track-based alignment and calibration of the pixel and strip detectors, the drift chamber or the muon system. …
The Belle II experiment at the SuperKEKB e+e- collider in KEK, Japan does start physics data-taking from early of 2018 with primary physics goal that is to probe the New Physics effect using heavy quark and lepton weak decays. During trigger and DAQ operation upon beam collision, it is important that Belle II detector (Fig. 1) status have to be monitored in a process of data-taking against an unexpected situation. Slow control system, built in the Control System Studio (CSS) which is a GUI window design tool based on Eclipse, is one of monitoring and controlling systems in Belle II operation. …
The Time-Of-Propagation detector is a Cherenkov particle identification detector based on quartz radiator bars for the Belle II experiment at the SuperKEKB electron-positron collider. The purpose of the detector is to identify the type of charged hadrons produced in electron-positron collisions, and requires a single photon timing resolution below 100 picoseconds. A novel front-end electronic system was designed, built, and integrated to acquire data from the 8192 microchannel plate photomultiplier tube channels in the detector. Waveform sampling of these analog signals is done by switched-cap…
The Belle II experiment currently under construction at the $e^+e^-$-collider SuperKEKB in Japan is designed to explore new physics beyond the standard model with an approximately 50 times larger data sample compared to its predecessor. The vertex detector (VXD), comprising a two layer DEPFET pixel detector (PXD) surrounded by four layers of double sided silicon strip detector (SVD), is indispensable for the accurate determination of the decay point of $B$ or $D$ meson as well as track reconstruction of low momentum particles. The DEPFET sensors in Belle II are thinned down to 75 $μ$m with low…
DEPFET active pixel sensors are a well-developed technology for vertex detectors at future colliders. Extensive test beam campaigns have proven the excellent performance of these devices, and their radiation hardness has been thoroughly tested. For the Belle-II experiment at the SuperKEKB collider, a new vertex detector based on DEPFET technology is being developed, using sensors thinned down to 75 μm. We give an overview over recent results with test devices using ILC pixel geometries as well as the concepts and challenges for the Belle-II pixel vertex tracker and discuss how the R&D for the …
The Belle II experiment at the Super B factory SuperKEKB, an asymmetric $e^+e^-$ collider located in Tsukuba, Japan, is tailored to perform precision B physics measurements. The centre of mass energy of the collisions is equal to the rest mass of the $Υ(4S)$ resonance of $m_{Υ(4S)} = 10.58\,\rm GeV$. A high vertex resolution is essential for measuring the decay vertices of B mesons. Typical momenta of the decay products are ranging from a few tens of MeV to a few GeV and multiple scattering has a significant impact on the vertex resolution. The VerteX Detector (VXD) for Belle II is therefore d…
The high design luminosity of the SuperKEKB electron-positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and mitigating these backgrounds is critical to the success of the Belle~II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positro…
The Silicon Vertex Detector (SVD), with its four double-sided silicon strip sensor layers, is one of the two vertex sub-detectors of Belle II operating at SuperKEKB collider (KEK, Japan). Since 2019 and the start of the data taking, the SVD has demonstrated a reliable and highly efficient operation, even running in an environment with harsh beam backgrounds that are induced by the world's highest instantaneous luminosity. In order to provide the best quality track reconstruction with an efficient pattern recognition and track fit, and to correctly propagate the uncertainty on the hit's positio…
Since the start of data taking in spring 2019 at the SuperKEKB collider (KEK, Japan) the Belle II Silicon Vertex Detector (SVD) has been operating reliably and with high efficiency, while providing high quality data: high signal-to-noise ratio, greater than 99% hit efficiency, and precise spatial resolution. These attributes, combined with stability over time, result in good tracking efficiency. Currently the occupancy, dominated by beam-background hits, is quite low (about 0.5% in the innermost layer), causing no problems to the SVD data reconstruction. In view of the operation at higher lumi…
The Belle-II experiment and superKEKB accelerator will form a next generation B-factory at KEK, capable of running at an instantaneous luminosity 40 times higher than the Belle detector and KEKB. This will allow for the elucidation of many facets of the Standard Model by performing precision measurements of its parameters, and provide sensitivity to many rare decays that are currently inaccessible. This will require major upgrades to both the accelerator and detector subsystems. The imaging Time-of-propagation (iTOP) detector will be a new subdetector of Belle-II that will perform an integral …
The physics goals the Belle II experiment require an exceptionally good alignment of all the components of the Belle II tracker. The Belle II tracker is composed of the DEPFET based pixel silicon detector, four layers of double sided silicon strip detector, a low material budget drift chamber, all three operating in a solenoidal 1.5 T B field, which is affected by the final focusing system of the accelerator. Each component of these three components must be aligned with an accuracy significantly better than the point resolution of the detector that for the PXD is order of 10 microns. The Belle…
This paper is based on the outcome of the activity that has taken place during the recent workshop on "SuperB in Italy" held in Frascati on November 11-12, 2005. The workshop was opened by a theoretical introduction of Marco Ciuchini and was structured in two working groups. One focused on the machine and the other on the detector and experimental issues. The present status on CP is mainly based on the results achieved by BaBar and Belle. Estabilishment of the indirect CP violation in B sector in 2001 and of the direct CP violation in 2004 thanks to the success of PEP-II and KEKB e+e- asymmetr…
Upgrade of the Belle II Vertex Detector with Depleted Monolithic CMOS Active Pixel Sensors
Marietta Blau Institute for Particle Physics, Austrian Academy of Sciences（玛丽亚·布劳粒子物理研究所，奥地利科学院）；Department of Engineering and Applied Sciences, University of Bergamo（贝加莫大学工程与应用科学学院）；Department of Electrical, Computer and Biomedical Engineering, University of Pavia（帕维亚大学电气、计算机和生物医学工程系）；Dipartimento di Fisica “E. Fermi”, Università di Pisa（比萨大学“E. 费米”物理系）；INFN Sezione di Pisa（意大利国家核物理研究所比萨分部）；Aix Marseille Univ, CNRS IN2P3, CPPM（艾克斯-马赛大学，法国国家科学研究中心，法国国家核物理与粒子物理研究所，普罗旺斯粒子物理中心）；Laboratoire de Physique des 2 infinis Irène Joliot-Curie – IJCLab, Université Paris-Saclay, CNRS IN2P3（巴黎-萨克雷大学，法国国家科学研究中心，法国国家核物理与粒子物理研究所，伊雷娜·约里奥-居里双无限物理实验室）；Université de Strasbourg, CNRS, IPHC UMR 7178（斯特拉斯堡大学，法国国家科学研究中心，高能物理研究所）；Physikalisches Institut, Rheinische（莱茵（威斯特法伦）联邦工业大学物理学院）
Belle II实验为应对更高的亮度，计划升级顶点探测器，采用耗尽单片主动像素传感器，设计高辐射容忍度和低功耗性能。
The Pixel Detector (PXD) of the Belle II experiment at superKEKB accelerator in Japan is based in the DEPFET technology. Two layers of 8+12 modules at a radius of 13 and 22 mm will give a spatial resolution below 10 mm. The radiation level expected in the first layer in ten years of operation is about 10 MRad of total ionizing dose. In order to study the tolerance of the DEPFET technology sixty devices were irradiated using a standard procedure like 60Co gamma source. Different doping types, channel sizes and biasing conditions were studied
On-detector digital electronics in High-Energy Physics experiments is increasingly being implemented by means of SRAM-based FPGA, due to their capabilities of reconfiguration, real-time processing and multi-gigabit data transfer. Radiation-induced single event upsets in the configuration hinder the correct operation, since they may alter the programmed routing paths and logic functions. In most trigger and data acquisition systems, data from several front-end modules are concentrated into a single board, which then transmits data to back-end electronics for acquisition and triggering. Since th…
