DOCSLIB.ORG

Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 2013 Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses Chen Xu College of William & Mary - Arts & Sciences Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Condensed Matter Physics Commons, and the Physical Chemistry Commons Recommended Citation Xu, Chen, "Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses" (2013). Dissertations, Theses, and Masters Projects. Paper 1539623621. https://dx.doi.org/doi:10.21220/s2-4cbq-f475 This Dissertation is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Advanced Topographic Characterization of Variously Prepared Niobium Surfaces and Linkage to RF Losses Chen Xu Beijing, Beijing, China Master of Science, Tsinghua University, 2007 Bachelor of Science, Fudan University, 2005 A Dissertation presented to the Graduate Faculty of the College of William and Mary in Candidacy for the Degree of Doctor of Philosophy Department of Applied Science The College of William and Mary May,2013 ©Copyright by _Chen Xu, 2013 All Rights Reserved APPROVAL PAGE This Dissertation is submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Chen Xu Approved by the Committee, Feb 2013 iy L f \ f. ■ Committee Chair Professor Micheal J Kelley, Applied Sdience Departments College of William and Mary Profe' rsor wriliam Cooke, Physics Department College of William and Mary Professor Gunter Lupke, Applied Science Departments College of William and Mary Dr Charles E. Reece, SRF Institute Thomas Jefferson National Accelerator Facility ABSTRACT Superconducting radio frequency (SRF) technology is widely adopted in particle accelerators. The shallow penetration (~ 40 nm) of the RF into superconducting niobium lends great importance to SRF cavity interior surface chemistry and topography. These in turn are strongly influenced by the chemical etching “surface clean-up” that follows fabrication. The principal surface smoothing methods are buffered chemical polish (BCP) and electropolish (EP). The resulting topography is characterized by atomic force microscopy (AFM). The power spectral density (PSD) of AFM data provides a more thorough description of the topography than a single-value roughness measurement. In this work, one dimensional average PSD functions derived from topography of BCP and EP with different controlled starting conditions and durations have been fitted with a combination of power law, K-correlation, and shifted Gaussian models to extract characteristic parameters at different spatial harmonic scales. While the simplest characterizations of these data are not new, the systematic tracking of scale-specific roughness as a function of processing is new and offers feedback for tighter process prescriptions more knowledgably targeted at beneficial niobium topography for SRF applications. Process development suffers because the cavity interior surface cannot be viewed directly without cutting out pieces, rendering the cavities unavailable for further study. Here we explore replica techniques as an alternative, providing imprints of cavity internal surface that can be readily examined. A second matter is the topography measurement technique used. Atomic force microscopy (AFM) has proven successful, but too time intensive for routine use. We therefore introduce white light interferometry (WLI) approach as an alternative. We examined real surfaces and their replicas, using AFM and WLI. W e find that the replica/WLI is promising to provide the large majority of desired information, so that use of the time-intensive AFM approach can be limited to where it is genuinely necessary. The prevalent idea is that sharp features could lead to magnetic quench or enhance the thermal quench. In this report, a calculation on magnetic field is numerically given on fine structure by finite element and conformal mapping methods. Corresponding RF Ohmic loss will be simulated. A certain thermal tolerant will be calculated. A Q~E curve will be predicted from this model. A perturbation model is utilized to calculate rough surface additional RF loss based on PSD statistical analysis. This model will not consider that superconductor will become normal at field higher than transition field. Therefore, it is only expected to explain mid­ field Q performance. One can calculate the RF power dissipation ratio between rough surface and ideal smooth surface within this field range. Additionally, the resistivity of Nb is temperature and magnetic field dependent from classic thermal feedback model theory. Combining with topographic PSD analysis and Rs temperature and field dependency, a middle field Q slope model could be modeled and the contribution from topography can be simulated. TABLE OF CONTENTS Acknowledgements iii Dedication iv List of Tables v List of Figures vi Chapter 1. Introduction 1 Chapter 2. Superconductivity, surfacetreatments and cavity testing 6 Chapter 3. Enhanced Characterization of Niobium Surface Topography 19 Chapter 4. A topographic power spectral density study of the effect of surface treatment processes on niobium for SRF accelerator cavities 52 Chapter 5. Characterization of Nb SRF cavity materials by White light interferometry and replica techniques 92 Chapter 6. Mechanism of Contribution to Niobium SRF cavities linear RF loss due to topographic surface structures 112 Chapter 7. Superconducting cavity rough surface and interior Magnetic field calculation and explanation of Non-linear surface resistant at high field 124 Appendix A 155 Appendix B 166 Appendix C 175 i Appendix D Autobiography ACKNOWLEDGEMENTS There are many people who have contributed time, knowledge, skill and support to the successful completion of this dissertation. Firstly, I wish to extend my thanks to my advisors Dr Michael J.Kelley and Dr Charles E. Reece for their patience and guidance on my research, study and editing of this manuscript. Without their support and guidance, this work would not have been done. I also really appreciate Dr Gunter Luepke and Dr William Cooke for taking time out of their busy schedule to serve as my dissertation committee members. Their attention, advice and review of this dissertation are extremely valuable to me. Secondly, I wish to acknowledge the exceptional support from SRF institute in Jefferson Lab: Dr Larry Philips, Dr Rongli Geng, Dr Haipeng Wang, Dr Hui Tian for their helpful instruction and discussion. Dr Xin Zhao, Dr Grigory Eremeev, Dr Gianluigi Ciovati, Anne-Marie Valente-Feliciano, Dr Peter Kneisel, Dr Robert Rimmer, Dr Andy T Wu, Dr Jiquan Guo, Dr Shaoheng Wang, Dr Ari Palczewski, Dr Pashupati Dhakal, Dr Todd Satogata, Dr Geoffrey Kraft, Olga Trogimova, Amy Wilkerson and Gary Cheng for their kind help and discussion. Carolyn Camp, for her helpful communication and organization; Stephen Dutton and Michael Morrone, for their electrionic works; I would like also express my thank to Dr Peter Takacs in Brookhaven national lab and Dr Alex Gruvich in Old Dominion University and Dr Xiaoxiong Gu from IBM Yorktown NY for their kind discussions. Thirdly, I would like to thank my officemates, Dr Binping Xiao, Dr Song Jin, Dr Jin Dai , Dr Senthilraja Singaravelu, Liang Zhao, Feisi He , Yongming Li, Jarnadan Upadhyay and Suba De Silva. I would like thank all my friends in the college of William and Mary, in Jefferson Lab, In Old Dominion University. Finally, I wish to express my deepest thanks for the unconditional trust, support and love from my family. Dedicated to Shuqin Wu and Zhongyi Zhao, Jie Zhao and Anxiang Xu. LIST OF TABLES Table 3.1 Averaged Rq and Rdq parameters with and without third order polynomial detrending with AFM scan range 100 pm by 100 pm 50 Table 3.2 Fitting parameters of samples of Single Crystal samples 50 Table 3.3 Lateral lengths and angles between given two cursors 50 Table 3.4 Fitting parameters of Incremental Nanopolished samples 51 Table 3.5 Fitting parameters of Incremental EP samples 51 Table 4.1 Summary of the effect of BCP treatment on topography of nanopolished single crystals 86 Table 4.2 The fitting parameters of Single Crystal Samples 87 Table 4.3 Summary of RMS values on the effect of BCP treatment on topography of fine-grained, nanopolished polycrystalline niobium 88 Table 4.4 Lateral lengths and angles between given two cursors 88 Table 4.5 The fitting parameter of nanopolished samples 89 Table 4.6 Effect of initial EP on fine-grained Nb previously subjected to BCP 89 Table 4.7 the fitting parameter of Incremental light EP Samples at 20°C 90 Table 4.8 Effect of full EP conversion on fine-grained Nb previously subjected to 100 pm BCP 90 Table 4.9 Fitting parameters of Incremental heavy EP Samples at 30°C 91 Table 5.1 Characterization Parameters for white light interferometry 111 Table 6.1 Averaged /?qwith AFM and WLI on different treatments 124 Table 7.1: The temperature, RBCS, Super/ normal conducting RF loss and its percentage are shown as a function of different H 154 v LIST OF FIGURES Figure 2.1 Vertical Testing Areas in Jlab 17 Figure 2.2 Diagram of a typical cavity testing structure 17 Figure 2.3 Surface magnetic field is illustrated on CEBAF 7 cells cavities
Load more

Recommended publications
  • Superkekb VACUUM SYSTEM K
    SuperKEKB VACUUM SYSTEM K. Shibata#, KEK, Tsukuba, Japan Abstract size in the horizontal and vertical directions at the IP, I is SuperKEKB, which is an upgrade of the KEKB B- the beam current, y is the vertical beam-beam * factory (KEKB), is a next-generation high-luminosity parameter, y is the vertical beta function at the IP, RL electron-positron collider. Its design luminosity is 8.0× and Ry are the reduction factors for the luminosity and 1035 cm-2s-1, which is about 40 times than the KEKB’s vertical beam-beam tune-shift parameter, respectively, record. To achieve this challenging goal, bunches of both owing to the crossing angle and the hourglass effect. The beams are squeezed extremely to the nanometer scale and subscripts + and – indicate a positron or electron, the beam currents are doubled. To realize this, many respectively. At the SuperKEKB, crossing the beams by upgrades must be performed including the replacement of using the “nanobeam scheme” [3] makes it possible to * th beam pipes mainly in the positron ring (LER). The beam squeeze y to about 1/20 of KEKB’s size. In the pipes in the LER arc section are being replaced with new nanobeam scheme, bunches of both beams are squeezed aluminium-alloy pipes with antechambers to cope with extremely to the nanometer scale (0.3 mm across and 100 the electron cloud issue and heating problem. nm high) and intersect only in the highly focused region Additionally, several types of countermeasures will be of each bunch at a large crossing angle (4.8 degrees).
    [Show full text]
  • Commissioning of the KEKB B-Factoryinvited
    Proceedings of the 1999 Particle Accelerator Conference, New York, 1999 COMMISSIONING OF THE KEKB B–FACTORY K. Akai, N. Akasaka, A. Enomoto, J. Flanagan, H. Fukuma, Y. Funakoshi, K. Furukawa, J. Haba, S. Hiramatsu, K. Hosoyama, N. Huang∗, T. Ieiri, N. Iida, T. Kamitani, S. Kato, M. Kikuchi, E. Kikutani, H. Koiso, S.–I. Kurokawa, M. Masuzawa, S. Michizono, T. Mimashi, T. Nakamura, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, N. Ohuchi, K. Oide,D.Pestrikov†,K.Satoh, M. Suetake, Y. Suetsugu, T. Suwada, M. Tawada, M. Tejima, M. Tobiyama, N. Yamamoto, M. Yoshida, S. Yoshimoto, M. Yoshioka, KEK, Oho, Tsukuba, Ibaraki 305-0801, Japan, T. Browder, Univ. of Hawaii, 2505 Correa Road, Honolulu, HI 96822, U.S.A. Abstract The commissioning of the KEKB B–Factory storage rings started on Dec. 1, 1998. The two rings both achieved a stored current of over 0.5 A after operating for four months. The two beams were successfully collided several times. The commissioning stopped on Apr. 19, taking a 5-week break to install the Belle detector. 1 BRIEF HISTORY OF THE COMMISSIONING The KEKB B–Factory[1] consists of two storage rings, the LER (3.5 GeV, e+) and the HER (8 GeV, e−), and the in- jector Linac/beam-transport (BT) system. The Linac was upgraded from the injector for TRISTAN, and was com- missioned starting in June 1997, including part of the BT line. The injector complex was ready before the start of commissioning of the rings.[2] Figure 1 shows the growth of the stored currents in the two rings through the period of commissioning.
    [Show full text]
  • Present Status of Kekb Project
    PRESENT STATUS OF KEKB PROJECT Shin-ichi Kurokawa KEK, High Energy Accelerator Research Organization 1-1 Oho, Tsukuba-shi, Ibaraki-ken, 305-0801, Japan Abstract GeV electron and a 5.3-GeV positron collide and produce a pair of B meson and anti-B meson at rest at the Υ(4S) The KEK B-Factory, KEKB, is an asymmetric-energy, resonance. In the laboratory frame where an 8-GeV two-ring, electron-positron collider for B physics. Eight- electron and a 3.5-GeV positron collide, the B and anti-B GeV electrons stored in a high-energy ring (HER) and mesons move along the direction of the incoming 3.5- GeV positrons in a low-energy ring (LER) collide at electron, travel over a few hundred µm, and decay at an interaction point (IP), which BELLE detector different positions. By detecting the decay products, we surrounds. In order to facilitate detection of CP-violation can identify the B and anti-B mesons. This identification effect at the bottom-quark sector, the machine is designed is essential for studying CP-violation, which is a subtle to reach a luminosity of 1034cm-2s-1. Even with a high difference in behavior between particles and anti- beam-beam tuneshift of 0.052 and a small βy* of 1 cm at particles. IP, necessary currents in the rings amount to 1.1 A at HER and 2.6 A at LER. KEKB adopts new schemes to reach TSUKUBA IP the goal, such as ±11 mrad finite-angle collision at IP, non-interleaved-sextupole chromaticity correction to have HER LER HER large dynamic apertures, higher-order-mode-free normal LER conducting cavity called ARES and single-cell, single- mode, superconducting cavities to prevent coupled-bunch instabilities and combat heavy beam-loading, among others.
    [Show full text]
  • Status of Super-Kekb and Belle Ii∗
    Vol. 41 (2010) ACTA PHYSICA POLONICA B No 12 STATUS OF SUPER-KEKB AND BELLE II∗ Henryk Pałka The H. Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences Radzikowskiego 152, 31-342 Kraków, Poland (Received November 29, 2010) The status of preparations to Belle II experiment at the SuperKEKB collider is reviewed in this article. PACS numbers: 11.30.Er, 12.15.Hh, 13.20.He, 29.20.db 1. Introduction The Belle detector [1] has stopped data taking in June 2010. A decade- long operation of the experiment at the asymmetric beam energy electron- positron collider KEKB [2] resulted in a data sample of an integrated lumi- nosity exceeding 1 ab−1. This would not be possible without the excellent performance of the KEKB. The collider has reached the world record in- stantaneous luminosity of 2:2 × 1034 cm−2s−1 (Fig. 1), more than twice the design luminosity. Several technological innovations contributed to this achievement, among them crab cavities developed at KEK and successful implementation of continuous injection. Fig. 1. Time-line of KEKB peak luminosity. ∗ Lecture presented at the L Cracow School of Theoretical Physics “Particle Physics at the Dawn of the LHC”, Zakopane, Poland, June 9–19, 2010. (2595) 2596 H. Pałka By the precise measurement of the CKM angle φ1 by Belle and BaBar, its companion B-meson factory experiment at SLAC [3], the Kobayashi– Maskawa mechanism of CP violation [4] has been confirmed. Following the experimental confirmation M. Kobayashi and T. Maskawa were awarded the 2008 Nobel Prize in Physics. Numerous other physics results of B-meson factory experiments further support the hypothesis that the matrix of three- generation quark mixing is the dominant source of CP violation in B- and K-meson decays.
    [Show full text]
  • Overview of the KEKB Accelerators
    Nuclear Instruments and Methods in Physics Research A 499 (2003) 1–7 Overview of the KEKB accelerators S. Kurokawa, E. Kikutani* KEK, National High Energy Accelerator Organization, Oho 1-1, Tsukuba-shi, Ibaraki 305-0801, Japan Abstract An overview of the KEKB accelerators is given as an introduction of the following articles in this issue, first by summarizing the basic features of the machines, and then describing the improvements of the performance since the start of the physics experiment. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.20. Keywords: Colliding machine; Storage ring 1. Introduction osity by Belle from the start of the physics experiment in June 1999 up to November 2001. We have witnessed a steady improvement in the This steady improvement in the performance of performance of KEKB from the start of the KEKB and the achievement of unprecedented physics experiment in June 1999 to the present luminosity of 5:47 Â 1033 cmÀ2 sÀ1 are the culmi- time. To review this improvement, we list here nation of almost a 10-year effort by KEKB staff milestone dates of the peak luminosity: the peak members. There still remain many things to be luminosity of KEKB exceeded 1:0 Â 1033 cmÀ2 sÀ1 improved in KEKB, to first reach the design in April 2000, reached 2:0 Â 1033 cmÀ2 sÀ1 in July luminosity of 1 Â 1034 cmÀ2 sÀ1; and then to 2000, surpassed 3:0 Â 1033 and 4:0 Â 1033 cmÀ2 sÀ1 eventually exceed it. The papers compiled here in March and June 2001, and finally reached 5:47 Â summarize our efforts made for KEKB and were 1033 cmÀ2 sÀ1 in November 2001.
    [Show full text]
  • KEKB Accelerator Control System
    Nuclear Instruments and Methods in Physics Research A 499 (2003) 138–166 KEKB accelerator control system Nobumasa Akasaka, Atsuyoshi Akiyama, Sakae Araki, Kazuro Furukawa, Tadahiko Katoh*, Takashi Kawamoto, Ichitaka Komada, Kikuo Kudo, Takashi Naito, Tatsuro Nakamura, Jun-ichi Odagiri, Yukiyoshi Ohnishi, Masayuki Sato, Masaaki Suetake, Shigeru Takeda, Yasunori Takeuchi, Noboru Yamamoto, Masakazu Yoshioka, Eji Kikutani KEK, High Energy Accelerator Research Organization, Oho 1-1, Tsukuba Ibaraki 305-0801, Japan Abstract The KEKB accelerator control system including a control computer system, a timing distribution system, and a safety control system are described. KEKB accelerators were installed in the same tunnel where the TRISTAN accelerator was. There were some constraints due to the reused equipment. The control system is based on Experimental Physics and Industrial Control System (EPICS). In order to reduce the cost and labor for constructing the KEKB control system, as many CAMAC modules as possible are used again. The guiding principles of the KEKB control computer system are as follows: use EPICS as the controls environment, provide a two-language system for developing application programs, use VMEbus as frontend computers as a consequence of EPICS, use standard buses, such as CAMAC, GPIB, VXIbus, ARCNET, RS-232 as field buses and use ergonomic equipment for operators and scientists. On the software side, interpretive Python and SAD languages are used for coding application programs. The purpose of the radiation safety system is to protect personnel from radiation hazards. It consists of an access control system and a beam interlock system. The access control system protects people from strong radiation inside the accelerator tunnel due to an intense beam, by controlling access to the beamline area.
    [Show full text]
  • Agenda of the Twelfth KEKB Accelerator Review Committee March 19-21, 2007 in the Meeting Room on the First Floor of Building No.3, KEK
    The Twelfth KEKB Accelerator Review Committee Report Introduction The Twelfth KEKB Accelerator Review Committee meeting was held on March 19-21, 2007. Heino Henke and Shin-ichi Kurokawa were unable to attend this meeting. Appendix A shows the present membership of the Committee. The Twelfth Committee meeting followed the usual format of oral presentations by the KEKB staff members and discussion by the Committee members. The Agenda for the meeting is shown in Appendix B. The first day started with KEKB performance and, in particular, the progress on commissioning the crab cavities. The Upgrade Studies were then presented and continued on the second day. The Committee was again impressed by the high standard of the talks, both the technical content and the presentations themselves. The recommendations of the Committee were presented to the KEKB staff members before the close of the meeting. The Committee wrote a draft report during the meeting that was then improved and finalized by e-mail among the Committee members. Contents Executive Summary A. Foreword B. Summary C. Recommendations Findings and Recommendations 1) Overview 2) Beam Commissioning before Crab Cavity 3) Belle Status 4) BPM Displacement Monitor 5) Crab Cavity Overview 6) RF Design of Crab Cavity 7) Cryogenics, etc. 8) Horizontal Tests for Crab Cavities 9) Installation of Crab Cavity 10) Commissioning of Crab RF System 11) Beam Commissioning with Crab Cavity 12) Beam-Beam Effect with Crab Cavity 13) Observation of Crab Crossing with Streak Camera 14) Recent Upgrade Studies
    [Show full text]
  • The Belle II Experiment: Status and Prospects
    universe Article The Belle II Experiment: Status and Prospects Paolo Branchini † INFN Sezione di RomaTre Via Della Vasca Navale, 84, 00146 Roma, Italy; [email protected] † On behalf of the Belle II Collaboration. Received: 16 September 2018; Accepted: 29 September 2018; Published: 1 October2018 Abstract: The Belle II experiment is a substantial upgrade of the Belle detector and will operate at the SuperKEKBenergy-asymmetric e+e− collider. The accelerator has already successfully completed the first phase of commissioning in 2016. The first electron versus positron collisions in Belle II were delivered in April 2018. The design luminosity of SuperKEKB is 8 × 1035 cm−2 s−1, and the Belle II experiment aims to record 50 ab−1 of data, a factor of 50 more than the Belle experiment. This large dataset will be accumulated with low backgrounds and high trigger efficiencies in a clean e+e− environment. This contribution will review the detector upgrade, the achieved detector performance and the plans for the commissioning of Belle II. Keywords: flavor; dark matter 1. Introduction Even though the Standard Model (SM) is currently the best description of the subatomic world, it does not explain the complete picture. The theory incorporates only three out of the four fundamental forces, omitting gravity. Moreover, there are also important questions that it does not answer, such as the matter versus antimatter asymmetry in the number of quark and lepton generations. Many New Physics (NP) scenarios have been proposed. Experiments in high-energy physics search for NP using two complementary approaches. The first, at the energy frontier, is able to discover new particles directly produced in pp collisions (ATLAS, CMS).
    [Show full text]
  • Movable Collimator System for Superkekb
    PHYSICAL REVIEW ACCELERATORS AND BEAMS 23, 053501 (2020) Movable collimator system for SuperKEKB T. Ishibashi , S. Terui, Y. Suetsugu, K. Watanabe, and M. Shirai High Energy Accelerator Research Organization (KEK), 305-0801, Tsukuba, Japan (Received 3 March 2020; accepted 6 May 2020; published 13 May 2020) Movable collimators for the SuperKEKB main ring, which is a two-ring collider consisting of a 4 GeV positron and 7 GeVelectron storage ring, were designed to fit an antechamber scheme in the beam pipes, to suppress background noise in a particle detector complex named Belle II, and to avoid quenches, derived from stray particles, in the superconducting final focusing magnets. We developed horizontal and vertical collimators having a pair of horizontally or vertically opposed movable jaws with radiofrequency shields. The collimators have a large structure that protrudes into the circulating beam and a large impedance. Therefore, we estimated the impedance using an electromagnetic field simulator, and the impedance of the newly developed collimators is lower compared with that of our conventional ones because a part of each movable jaw is placed inside the antechamber structure. Ten horizontal collimators and three vertical collimators were installed in total, and we installed them in the rings taking the phase advance to the final focusing magnets into consideration. The system generally functioned, as expected, at a stored beam current of up to approximately 1 A. In high-current operations at 500 mA or above, the jaws were occasionally damaged by hitting abnormal beams, and we estimated the temperature rise for the collimator’s materials using a Monte Carlo simulation code.
    [Show full text]
  • The Belle II Experiment at the Superkekb
    EPJ Web of Conferences 218, 07003 (2019) https://doi.org/10.1051/epjconf/201921807003 PhiPsi 2017 The Belle II Experiment at the SuperKEKB Chang-Zheng Yuan (for the Belle II Collaboration )1;2;? 1Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China 2University of Chinese Academy of Sciences, Beijing 100049, China Abstract. 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. 1 Introduction The two B factories, Belle at the KEKB collider at KEK [1] and BaBar at the PEP II collider at SLAC [2], have been operating very successfully for more than ten years [3]. Altogether, about 1.5 ab−1 data in the vicinity of the Υ(4S ) resonance were accumulated, and these data were used in extensive studies of the B-physics, charm physics, tau physics, as well as hadron spectroscopy and various searches for possible hints of new physics, such as lepton number violation, low mass Higgs-like states, and dark matters. While most results from B factories are in good consistency with the expectations from the Stan- dard Model (SM), there are a few measurements that show discrepancies at around three standard deviation level from the SM predictions. One of the interesting examples is the possible observation of the violation of the lepton universality in semileptonic B decays, if confirmed, very probably, there is contribution from non-SM physics [4].
    [Show full text]
  • BUNCH by BUNCH FEEDBACK SYSTEMS for SUPERKEKB RINGS Makoto Tobiyama†, John W
    Proceedings of the 13th Annual Meeting of Particle Accelerator Society of Japan August 8-10, 2016, Chiba, Japan PASJ2016 TUOM06 BUNCH BY BUNCH FEEDBACK SYSTEMS FOR SUPERKEKB RINGS Makoto Tobiyama†, John W. Flanagan, KEK Accelerator Laboratory, 1-1 Oho, Tsukuba 305-0801, Japan, and Graduate University for Advanced Studies (SOKENDAI), 1-1, Oho, Tsukuba 305-0801, Japan Alessandro Drago, INFN-LNF, Via Enrico Fermi 40-00044, Frascati(Roma), Italy Abstract analysed by the unstable mode analysis with the grow- Bunch by bunch feedback systems for the SuperKEKB damp experiments. Also the related beam diagnostic tools rings have been developed. Transverse and longitudinal such as the bunch current monitor, large scale memory bunch feedback systems brought up in very early stages board, will be shown. of beam commissioning have shown excellent perfor- Table1: Main Parameters of SuperKEKB HER/LER in mance, and helped realize smooth beam storage and very Phase 1 Operation. quick vacuum scrubbing. Also, via grow-damp experi- ments and unstable mode analysis, they contributed to HER LER finding the possible source of an instability. The measured performance of the bunch feedback systems, together Energy (GeV) 7 4 with the performance of the bunch feedback related sys- Circumference(m) 3016 tems such as the bunch current monitor and betatron tune monitor are reported. Max. Beam current (mA) 1010 870 Max. Number of bunches 2455 2363 INTRODUCTION The KEKB collider has been upgraded to the Single bunch current (mA) 1.04 1.44 SuperKEKB collider with the final target of 40 times Min. bunch separation(ns) 4 higher luminosity than that of KEKB.
    [Show full text]
  • Kekb and Superkekb
    Proceedings of APAC 2004, Gyeongju, Korea KEKB AND SUPERKEKB H. Koiso∗, T. Abe, K. Akai, M. Akemoto, K. Ebihara, K. Egawa, A. Enomoto, J. Flanagan, S. Fukuda, H. Fukuma, Y. Funakoshi, K. Furukawa, T. Furuya, J. Haba, S. Hiramatsu, T. Honda, K. Hosoyama, T. Ieiri, N. Iida, H. Ikeda, S. Inagaki, S. Isagawa, T. Kageyama, S. Kamada, T. Kamitani, K. Kanazawa, S. Kato, T. Katoh, M. Kikuchi, E. Kikutani, T. Kubo, M. Masuzawa, T. Matsumoto, S. Michizono, T. Mimashi, T. Mitsuhashi, S. Mitsunobu, A. Morita, Y. Morita, H. Nakai, T. T. Nakamura, H. Nakanishi, H. Nakayama, Y. Ogawa, K. Ohmi, Y. Ohnishi, S. Ohsawa, N. Ohuchi, K. Oide, M. Ono, T. Ozaki, Y. Sakamoto, K. Shibata, T. Shidara, M. Shimada, M. Suetake, Y. Suetsugu, R. Sugahara, T. Sugimura, T. Suwada, Y. Takeuchi, Y. Takeuchi, M. Tawada, M. Tejima, M. Tobiyama, K. Tsuchiya, T. Tsukamoto, S. Uehara, S. Uno, S. S. Win† , N. Yamamoto, Y. Yamamoto, Y. Yano, K. Yokoyama, M. Yoshida, M. Yoshida, S. Yoshimoto, M. Yoshioka, KEK, Oho, Tsukuba, Ibaraki 305-0801, Japan S. Stanic, University of Tsukuba, Tennodai, Tsukuba, Ibaraki 305-8573, Japan F. Zimmermann, CERN, CH-1211, Geneve 23, Switzerland Abstract Superconducting cavities (HER) Belle detector The KEKB B-factory continues to improve the luminos- e- ity after having achieved the design value of 10/nb/s. Since Jan. 2004, KEKB is being operated in the Continuous In- KEKB B-Factory e+ jection Mode (CIM) which significantly boosts the inte- ARES copper grated luminosity. This paper presents recent progress of cavities (HER) KEKB and future plans one of which is introduction of crab crossing.
    [Show full text]