LHC-CC10, 4th LHC Crab Cavity Workshop

Europe/Zurich
6/2-024 - BE Auditorium Meyrin (CERN)

6/2-024 - BE Auditorium Meyrin

CERN

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Frank Zimmermann (AB/ABP), Rama Calaga (BNL), Rogelio Tomas (CERN)
Description

Workshop Charge:

1. Can compact cavities for the LHC be realized and made robust with the complex damping schemes ?

2. Are crab cavities compatible with LHC machine protection, or can they be made to be so ?

3. Should a KEKB crab cavity be installed in the SPS for test purposes ?

LHC-CC10 Summary Report
Project Document Draft
Participants
  • Alireza Nassiri
  • Benjamin Hall
  • Bruce STRAUSS
  • Chandra Bhat
  • Daniel Doherty
  • Daniel Wollmann
  • Edmond CIAPALA
  • Elena Chapochnikova
  • Elias Metral
  • Eric Jon Prebys
  • Eric Montesinos
  • Erk Jensen
  • Fartoukh Stephane
  • Frank Zimmermann
  • Fritz Caspers
  • Graeme Burt
  • Guido Sterbini
  • Hyung Jin Kim
  • Ilan Ben-Zvi
  • Javier Barranco Garcia
  • Jean Delayen
  • Jean-Philippe Tock
  • Jean-Pierre Koutchouk
  • Joachim Tückmantel
  • John Byrd
  • Jorg Wenninger
  • Karl-Martin Schirm
  • Luca Ficcadenti
  • Marek GASIOR
  • Massimo Giovannozzi
  • Mathieu Therasse
  • Maud Baylac
  • Ofelia Capatina
  • Oliver BRUNING
  • olivier brunner
  • Paul Collier
  • Philippe Lebrun
  • Pierre BOSLAND
  • Rama Calaga
  • Riccardo De Maria
  • Rogelio Tomas
  • Roland Garoby
  • Ryoichi Miyamoto
  • Stephane CHEL
  • Subashini De Silva
  • Tobias Baer
  • Tor Raubenheimer
  • Vittorio Parma
  • Werner Herr
  • Wolfgang HOFLE
  • Yolanda GOMEZ MARTINEZ
  • Yoshihiro Funakoshi
  • Zenghai Li
    • 08:30 10:10
      LHC-CC status & review 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 08:30
        Welcome & Workshop Overview 10m
        Speaker: Steve Myers (CERN)
      • 08:40
        KEK-B Achievements & Crabs 20m
        The implementation of large angle crab crossing using superconducting cavities operating on the TM110 mode. Beam commissioning, operation, cavity availability, reliability and luminosity increase from the crab crossing (purely geometric gain plus gain in beam-beam tune shift). KEKB crab-cavity diagnostics and set-up/tuning/alignment procedures. Frequency, reasons, beam observations, and possible mitigation of crab-cavity trips. Aperture issues. Ramping and leveling. KEKB upgrade plan without crab cavities and the reasons.
        Speaker: Yoshihiro Funakoshi (KEK)
        Slides
      • 09:00
        LHC luminosity achievements & limitations 20m
        LHC beams and luminosity evolution during the 2010 Run with some estimates on future projections. Present intensity limitations from operational experience and machine availability. Hints on upgrade beam parameters based on LHC experience (for example, lower emittance and higher than nominal beam-beam tune shift)
        Speaker: Oliver Bruning (CERN)
        Slides
      • 09:20
        Perspective from the Experiments 20m
        Detector upgrade plans and schedule for the experiments, and their alignment with planned LHC upgrade. Constraints and requirements from the experiments on the proposed upgrade scenarios with crab cavities, early separation with D0 dipole, and large Piwinski angle scheme. Planned civil engineering and upgrade work around IP's 1 and 5 that could have synergies or conflicts with a crab-cavity installation.
        Speaker: Dr Jordan Nash (Imperial College)
        Slides
      • 09:40
        HL-LHC Design Study & Crab Cavities 20m
        The motivation of the high luminosity LHC design study, goal, scope, required technologies, time line, technology choices and decision dates, overall cost estimate and resources. The collaborative framework of this design study with EuCARD, US and Japanese partners. R&D plan for the novel technologies, in particular for the crab cavities required to realize the full potential of the LHC upgrade foreseen by 2021.
        Speaker: Prof. Lucio Rossi (CERN)
        Slides
      • 10:00
        Discussion 10m
    • 10:10 10:30
      Coffee break 20m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 10:30 12:10
      Optics & Beam Physics Aspects 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 10:30
        Upgrade optics with crab cavities 20m
        Review of the main LHC optics constraints. New flexible upgrade optics and its beta* reach. Possible LHC baseline layout wtih crab cavities. Choice of beta*'s and crossing angle with local crab cavities. Optics consistency check and chromatic correction scheme. Potential crab cavity locations and the crab voltage required. Longitudinal space constraints. Transverse mechanical aperture requirements together with expected closed orbit excursion. Possible effects on dynamic aperture, synchro-betatron resonances and long-range beam beam, with associated nonlinear field tolerances.
        Speaker: Riccardo De Maria (CERN)
        Slides
      • 10:50
        Effect of non-zero dispersion 20m
        Effect of non-zero dispersion for a local crab crossing scheme for the LHC is considered and its impact on stable working point in the presence of crab cavities is analysed. The maximum allowed dispersion (and slope of dispersion?) at the crab-cavity is estimated. Effects of higher order optical aberrations and RF curvature, and their impact on the IR region optics and working point are also considered.
        Speaker: Prof. Georg Hoffstaetter (Cornell University, LEPP)
      • 11:10
        Impedance effects during injection, energ ramp & store 20m
        Review of longitudinal and transverse impedance budgets for the LHC energy cycle. Assessment of crab-cavity impedance spectrum for LHC compatibility.
        Speaker: Elena Chapochnikova (CERN)
        Slides
      • 11:30
        Luminosity leveling with crabs 20m
        Concept of lumonisity leveling and the effect of luminosity leveling with crab cavities at ultimate bunch intensities. The use of crab cavities for smaller than nominal emittances for operation with total beam-beam tune shifts of 0.02 to 0.03.
        Speaker: Guido Sterbini (CERN BE-ABP)
        Slides
      • 11:50
        Very large crossing angle & magnet technology 20m
        Assuming a successful implementation of the crab scheme with the current IR focusing layout, a future outlook with concepts and associated challenges for the magnet technology to devise independent focusing channels at the IRs for the two beams with larger-angle crab crossing. This could alleviate long range beam-beam problems and enable easier optics solutions for reducing beta*.
        Speaker: Dr Ezio Todesco (CERN)
        Slides
    • 12:10 14:05
      Lunch 1h 55m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 14:05 15:45
      Cavity Technology 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 14:05
        ICFA deflecting cavity workshop summary 20m
        A summary of the workshop held on Sept 1-3, 2010 to review the current state of the art deflecting cavity technologies and their application in high energy collider (LHC, KEK-B, ILC, CLIC, LHeC), generation of short x-ray pulses in synchrotron light sources (APS, Spring-8), beam manipulations, emittance exchange and diagnostics. Strategies on cavity design optimization and challenges confronting novel concepts.
        Speaker: Dr Alireza Nassiri (Argonne National Laboratory - DOE)
        Slides
      • 14:25
        EuCARD cavity developments 15m
        The development of the 4-rod cavity at 400 MHz toward a crab cavity for the LHC. Detailed cavity-coupler design including deflecting mode characteristics, HOM spectra and achievable damping, coupler configurations, mechanical tolerances, tuning concepts, multipacting and non-linearity of deflecting voltage with transverse offset. Additionally cavity fabrication, treatment, assembly of coupler, Helium vessel and ancillary equipment should be foreseen within the design concept.
        Speaker: Graeme Burt (Cockcroft Institute)
        Slides
      • 14:40
        LARP cavity developments 15m
        The development of the single rod half-wave cavity at 400 MHz toward a crab cavity for the LHC. Detailed cavity-coupler design including deflecting mode characteristics, HOM spectra and achievable damping, coupler configurations, mechanical tolerances, tuning concepts, multipacting and non-linearity of deflecting voltage with transverse offset. Additionally cavity fabrication, treatment, assembly of coupler, Helium vessel and ancillary equipment should be foreseen within the design concept.
        Speaker: Zenghai Li (SLAC)
        Slides
      • 14:55
        KEK cavity developments 15m
        Detailed cavity-coupler design including deflecting mode characteristics, HOM spectra and achievable damping, coupler configurations, mechanical tolerances, tuning concepts, multipacting and non-linearity of deflecting voltage with transverse offset. Additionally cavity fabrication, treatment, assembly of coupler, Helium vessel and ancillary equipment should be foreseen within the design concept.
        Speaker: kenji hosoyama (KEK, High Energy Accelerator Research Organization)
        Slides
      • 15:10
        ODU/JLab cavity development 15m
        The development of the parallel bar cavity at 400 MHz toward a crab cavity for the LHC. Detailed cavity-coupler design including deflecting mode characteristics, HOM spectra and achievable damping, coupler configurations, mechanical tolerances, tuning concepts, multipacting and non-linearity of deflecting voltage with transverse offset. Additionally cavity fabrication, treatment, assembly of coupler, Helium vessel and ancillary equipment should be foreseen within the design concept.
        Speaker: Jean Delayen (Thomas Jefferson National Accelerator Facility)
        Slides
      • 15:25
        The Quarter Wave Resonator as a Crabbing Cavity 10m
        Speaker: Ilan Ben-Zvi (Brookhaven National Laboratory)
        Slides
      • 15:35
        Discussion, Cavity Technology 10m
    • 15:45 16:00
      Coffee break 15m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 16:00 18:00
      Cryomodule & Instrumentation 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 16:00
        Slim elliptical cavity at 800 MHz for local crab crossing 20m
        A slim highly eccentric elliptical cavity with vertical deflection at 800 MHz, compatible to beam line distances everywhere in the LHC ring, was designed; it is a good fall-back solution in case of problems with new compact 400 MHz designs. RF characteristics of the deflecting mode, HOM spectra and damping, tuning and multipacting are presented.
        Speaker: Luca Ficcadenti (INFN)
        Slides
      • 16:20
        Coupler (FPC & HOM) concepts for compact cavities 20m
        Review the current design aspects of the fundamental power coupler and HOM couplers for the compact cavity designs. Feasibility and robustness of such couplers for the LHC crab cavity from the perspective of HOM damping, fabrication, assembly and operation is considered. These concepts are compared to the conventional coupling and damping systems for cavity-coupler concepts.
        Speaker: Wolfgang Weingarten (CERN)
        Slides
      • 16:40
        Thermal & mechnical analysis for compact cavities 20m
        Thermal and mechanical consideration for the compact cavities under considered for the LHC as compared to the conventional cavities in accelerators. General mechanical and thermal considerations for cryomodule hosting the compact cavities, including modelling tools, stress analysis, tuning, alignment, impact of the accelerator environment, issues and input for LHC cavity designs
        Speaker: Vittorio Parma (CERN)
        Slides
      • 17:00
        Tuner concepts for compact cavities 20m
        Review of the state of the art tuning systems for SRF cavities in accelerators and potential robust concepts for compact cavity designs to achieve both slow and fast tuning range and tolerances. Design aspects, cryomodule integration and operational considerations including potential issues for the tuning concepts considered for the compact cavities.
        Speaker: Dr Alireza Nassiri (Argonne National Laboratory - DOE)
        Slides
    • 08:30 10:10
      Crab Cavity Beam Studies 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 08:30
        KEK-B noise experiments 20m
        Dedicated beam experiments in KEKB with crab cavities with induced noise to study the impact on beam quality, lifetime and luminosity. The observations of beam-beam instability between the sigma and pi modes and simlations to explain this phenomena is presented. Tolerances based on KEKB measurements for the LHC is derived. The first measurement of crab dispersion using orbit differences with and without crabs is compared to the model.
        Speaker: Rogelio Tomas (CERN)
        Slides
      • 08:50
        SPS beam tests with crab cavities 20m
        Feasibility study of KEK-B crab cavities for beam tests in the LHC, infrastructure, cryogenics, collimator configuration and physics objectives for crab cavity tests in the SPS. First results from SPS beam experiments as preparatory steps for a future crab tests in the SPS.
        Speaker: Dr Elias METRAL (CERN)
        Slides
      • 09:10
        Beam simulations for SPS tests 20m
        Crab cavities are foreseen to be tested in the SPS as a proof of principle before a full implementation in the LHC. Simulated effects of a single crab cavity on the SPS hadron beam, including ideal energy, stable working points, effect of non-zero dispersion, emittance growth and lifetime for crab tests in the SPS. Comparisons to the recent experiments in the SPS for emittance lifetime during a coast at 55 GeV/c without crab cavities.
        Speaker: Hyung Jin Kim (FNAL)
        Slides
      • 09:30
        SPS (and LHC) instrumention for crabbed beams 20m
        Available instrumentation in the SPS and LHC to measure signature of crabbed beams, crossing angles in LHC, crab dispersion and head-tail closed orbits. Beam measurements of crab cavity amplitude and phase control using closed orbit distortion, orbit offsets at IP and luminosity measurements, orbit control and feedback near crab cavities and other instrumentation used for crab tests and operation.
        Speaker: Marek Gasior (CERN)
        Slides
      • 09:50
        Discussion, Beam tests & Technology choice for SPS 20m
    • 10:10 10:30
      Coffee break 20m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 10:30 12:30
      Machine Protection 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 10:40
        Machine Protection Specifications 10m
        Speaker: Dr Jorg Wenninger (CERN)
        Slides
      • 10:50
        How to make crabs LHC safe & collimation compatible 10m
        Review of LHC machine protection and LHC collimation system. Constraints and requirements that crab cavities must comply with. Possible approaches for ensuring their compatibility.
        Speaker: Daniel Wollmann
        Slides
      • 11:00
        Failure scenarios and mitigation 20m
        Crab cavity failures such as abrupt amplitude and phase changes, RF trips, cavity quench are characterized with appropriate time scales. Their potential impact on the LHC beams and mitigation of such failure scenarios within the LHC machine protection constraints is discussed.
        Speaker: Joachim Tuckmantel (CERN)
      • 11:20
        KEK-B crab trips & RF signals 20m
        Cavity trips and associated RF & beam observations at KEKB. Types of trips, their signature and the (presumed) root causes. Possible mitigation schemes for LHC.
        Speaker: Kota Nakanishi (Japan/KEK)
        Slides
      • 11:40
        LHC studies for RF trips 20m
        Results from particle tracking using the LHC collimation system in Sixtrack and MADX to determine local signatures of the particle losses due to abrupt crab cavity failures. Detailed scans to determine specifications on fast cavity failures is derived to ensure machine preotection during the LHC cycle at ultimate intensities. Some aspects of upgrade optics is also studied.
        Speakers: Rama Calaga (BNL), Tobias Baer (Universitaet Hamburg)
      • 12:00
        Interplay of transverse damper and crab cavities 20m
        Transverse damper settings in the presence of crabbed beams and beam-beam. The interplay between the damper and the crab cavity for single bunch and bunch trains. Suppression of the effect of phase noise on the beam and of potential instabilities from crab cavities to relax tolerances on crab-cavity RF controls.
        Speaker: Wolfgang Hofle (CERN)
        Slides
      • 12:20
        Discussion, Machine Protection 10m
    • 12:30 14:00
      Lunch 1h 30m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 14:00 15:40
      RF Controls & Testing 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 14:00
        KEKB crab RF architecture & controls 20m
        RF system architecture of the KEKB crab cavities including high power RF system and LLRF controls. Amplitude and phase tolerances and stability, compensation of beam loading, closed orbit and beam instabilities. Possible improvements for achieving fewer "RF trips" including operating temperature, design aspects etc..
        Speaker: Kota Nakanishi (Japan/KEK)
      • 14:20
        SM18 test stand for crabs 20m
        Cryomodule assembly options at CERN, test stand for low power and high power testing, high power RF availability, availability of cryogenics, gradient performance, cavity-coupler conditioning, instrumentation, mechanical, transport issues and quality control.
        Speaker: Olivier Brunner (CERN)
        Slides
      • 14:40
        Cryogenics for SPS, LHC & SM18 20m
        Operating temperature options, crab specific cryogenics at IR1, IR5, IR4, SPS & SM18, Helium pressure and availability, cryo circuits and controls, safety valves and protection, overall installation effort,cost and time line, heat loads, impact on the overall LHC during regular operation
        Speaker: Bruno Vullierme (CERN)
        Slides
      • 15:00
        LLRF considerations for Crab Cavities 20m
        I will first briefly present the LHC reference RF generation (one per ring) and the LLRF field control (one system per cavity). I will then concentrate on the issue of RF phase noise: The performance achieved with the LHC cavities will be presented in details and we will try to extrapolate these results to the Crab Cavities. A possible interfacing of the Crab Cavities with the 400 MHz reference RF and with the Control System (Functions) will be described. The operational scenario will then be outlined: RF controls to make a detuned crab cavity at "zero" voltage invisible to the beam over the LHC injection and ramp while retuning and gradually ramping the cavity voltage over the course of a physics store to perform luminosity leveling. Finally a candidate prototype LLRF system will be presented.
        Speaker: Philippe Baudrenghien (CERN)
        Slides
    • 15:40 16:00
      Coffee Break 20m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 16:00 18:00
      Schedule & Future Outlook 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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      • 16:00
        Field quality and non-linearity of deflecting mode 20' 20m
        Due to the high beta functions at the location of the local crab cavities, there is a stringent limit on the maximum allowable non-linearities of the deflecting field. Field quality and higher-order harmonics for a conventional ellitpical crab cavity and for LHC compact crab cavities are analysed, and their impact on the cavity design is considered. Aspects related to beam loading due to transverse offset and phase jitter are also addressed.
        Speakers: Dr Erk Jensen (CERN), Rama Calaga (BNL)
        Slides
      • 16:20
        Overall planning of RF infrastructure 20m
        Outline of the crab cavity work package within the HL-LHC upgrade including the potential collaborators, distribution of R&D tasks, time line for R&D and construction, cost estimate over the duration of the project, and man power estimates.
        Speaker: Dr Erk Jensen (CERN)
      • 16:40
        LHeC, HE-LHC other crab cavity applications 20m
        Possible future crab-cavity applications, including their merits and rough parameters, for HL-LHC, LHeC, HE-LHC, ILC, CLIC, and other projects.
        Speaker: Dr Frank Zimmermann (AB/ABP)
        Slides
      • 17:00
        Place Holder 20m
      • 17:20
        Discussion, Schedule, Planning & Future 20m
    • 14:00 15:40
      Summary Sessions I 60-6-015

      60-6-015

      CERN

      • 14:00
        LHC-CC Status & Review 20m 60-6-015

        60-6-015

        CERN

        Speaker: Jean-Pierre Koutchouk (CERN)
        Slides
      • 14:20
        Optics & Beam Physics Aspects 20m 60-6-015

        60-6-015

        CERN

        Speaker: Dr Massimo Giovannozzi (CERN)
        Slides
      • 14:40
        Cavity Technology 20m 60-6-015

        60-6-015

        CERN

        Speaker: Edmond Ciapala (CERN)
        Slides
      • 15:00
        Cryomodule & Instrumentaion 20m 60-6-015

        60-6-015

        CERN

    • 15:40 16:00
      Coffee Break 20m 6/2-024 - BE Auditorium Meyrin

      6/2-024 - BE Auditorium Meyrin

      CERN

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    • 16:00 17:40
      Summary Sessions II 60-6-015

      60-6-015

      CERN

      • 16:00
        Crab Cavity Beam Studies 20m 60-6-015

        60-6-015

        CERN

        Speaker: Paul Collier (CERN)
        Slides
      • 16:20
        Machine Protection 20m 60-6-015

        60-6-015

        CERN

        Speaker: Dr Jorg Wenninger (CERN)
        Slides
      • 16:40
        RF Controls & Testing 20m 60-6-015

        60-6-015

        CERN

        Speaker: Jean Delayen (Thomas Jefferson National Accelerator Facility)
        Slides
      • 17:00
        Schedule & Future Outlook 20m 60-6-015

        60-6-015

        CERN

        Speaker: Roland Garoby (CERN)
        Slides
    • 17:40 18:30
      Advisory board discussion 60-6-015

      60-6-015

      CERN