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LHC-CC10, 4th LHC Crab Cavity Workshop
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Europe/Zurich
6/2-024 - BE Auditorium Meyrin (CERN)
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 ?
Support
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
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LHC-CC status & review 6/2-024 - BE Auditorium Meyrin
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1
Welcome & Workshop OverviewSpeaker: Steve Myers (CERN)
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2
KEK-B Achievements & CrabsThe 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)
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3
LHC luminosity achievements & limitationsLHC 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)
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4
Perspective from the ExperimentsDetector 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)
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5
HL-LHC Design Study & Crab CavitiesThe 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)
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6
Discussion
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1
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10:10
Coffee break 6/2-024 - BE Auditorium Meyrin
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Optics & Beam Physics Aspects 6/2-024 - BE Auditorium Meyrin
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7
Upgrade optics with crab cavitiesReview 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)
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8
Effect of non-zero dispersionEffect 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)
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Luminosity leveling with crabsConcept 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)
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11
Very large crossing angle & magnet technologyAssuming 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)
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7
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12:10
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Cavity Technology 6/2-024 - BE Auditorium Meyrin
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12
ICFA deflecting cavity workshop summaryA 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)
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13
EuCARD cavity developmentsThe 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)
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LARP cavity developmentsThe 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)
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15
KEK cavity developmentsDetailed 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)
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ODU/JLab cavity developmentThe 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)
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Discussion, Cavity Technology
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12
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15:45
Coffee break 6/2-024 - BE Auditorium Meyrin
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Cryomodule & Instrumentation 6/2-024 - BE Auditorium Meyrin
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19
Slim elliptical cavity at 800 MHz for local crab crossingA 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)
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Coupler (FPC & HOM) concepts for compact cavitiesReview 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)
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Thermal & mechnical analysis for compact cavitiesThermal 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 designsSpeaker: Vittorio Parma (CERN)
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Tuner concepts for compact cavitiesReview 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)
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19
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Crab Cavity Beam Studies 6/2-024 - BE Auditorium Meyrin
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23
KEK-B noise experimentsDedicated 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)
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SPS beam tests with crab cavitiesFeasibility 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)
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Beam simulations for SPS testsCrab 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)
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SPS (and LHC) instrumention for crabbed beamsAvailable 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)
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Discussion, Beam tests & Technology choice for SPS
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23
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10:10
Coffee break 6/2-024 - BE Auditorium Meyrin
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Machine Protection 6/2-024 - BE Auditorium Meyrin
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Failure scenarios and mitigationCrab 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)
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LHC studies for RF tripsResults 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)
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Interplay of transverse damper and crab cavitiesTransverse 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)
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34
Discussion, Machine Protection
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12:30
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RF Controls & Testing 6/2-024 - BE Auditorium Meyrin
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35
KEKB crab RF architecture & controlsRF 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)
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SM18 test stand for crabsCryomodule 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)
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Cryogenics for SPS, LHC & SM18Operating 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 operationSpeaker: Bruno Vullierme (CERN)
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38
LLRF considerations for Crab CavitiesI 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)
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35
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15:40
Coffee Break 6/2-024 - BE Auditorium Meyrin
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Schedule & Future Outlook 6/2-024 - BE Auditorium Meyrin
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39
Field quality and non-linearity of deflecting mode 20'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)
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40
Overall planning of RF infrastructureOutline 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)
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Place Holder
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Discussion, Schedule, Planning & Future
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Summary Sessions I 60-6-015
60-6-015
CERN
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47
Cryomodule & Instrumentaion 60-6-015
60-6-015
CERN
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15:40
Coffee Break 6/2-024 - BE Auditorium Meyrin
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Summary Sessions II 60-6-015
60-6-015
CERN
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Advisory board discussion 60-6-015
60-6-015
CERN
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