“LHC-CC08” Joint BNL/US-LARP/CARE-HHH Mini-Workshop on Crab Cavities for LHC Frank Zimmermann Thanks to Ilan Ben-Zvi, Rama Calaga, Walter Scandale, Yi-Peng Sun, Rogelio Tomas PAF Meeting 14 April 2008 We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)  

Crab Potential analytical formula tracking with Guinea-Pig Y.-P. Sun

Reminder: LHC upgrade paths early separation (ES) full crab crossing (FCC) L. Evans, W. Scandale, F. Zimmermann J.-P. Koutchouk stronger triplet magnets D0 dipole small-angle crab cavity stronger triplet magnets small-angle crab cavity ultimate beam (1.7x1011 protons/bunch, 25 spacing), b* ~10 cm early-separation dipoles in side detectors , crab cavities → hardware inside ATLAS & CMS detectors, first hadron crab cavities; off-d b ultimate LHC beam (1.7x1011 protons/bunch, 25 spacing) b* ~10 cm crab cavities with 60% higher voltage → first hadron crab cavities, off-d b-beat wire compensator larger-aperture triplet magnets large Piwinski angle (LPA) 50 ns spacing, longer & more intense bunches (5x1011 protons/bunch) b*~25 cm, no elements inside detectors long-range beam-beam wire compensation → novel operating regime for hadron colliders, beam generation F. Ruggiero, W. Scandale. F. Zimmermann

full crab crossing (FCC) large Piwinski angle (LPA) parameter symbol nominal ultimate Early Sep. Full Crab Xing L. Piw Angle transverse emittance e [mm] 3.75 protons per bunch Nb [1011] 1.15 1.7 4.9 bunch spacing Dt [ns] 25 50 beam current I [A] 0.58 0.86 1.22 longitudinal profile Gauss Flat rms bunch length sz [cm] 7.55 11.8 beta* at IP1&5 b* [m] 0.55 0.5 0.08 0.25 full crossing angle qc [mrad] 285 315 381 Piwinski parameter f=qcsz/(2*sx*) 0.64 0.75 2.0 hourglass reduction 1 0.99 peak luminosity L [1034 cm-2s-1] 2.3 15.5 10.7 peak events per #ing 19 44 294 403 initial lumi lifetime tL [h] 22 14 2.2 4.5 effective luminosity (Tturnaround=10 h) Leff [1034 cm-2s-1] 0.46 0.91 2.4 2.5 Trun,opt [h] 21.2 17.0 6.6 9.5 (Tturnaround=5 h) 0.56 3.6 3.5 15.0 12.0 4.6 6.7 e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) 0.36 (0.1) SR heat load 4.6-20 K PSR [W/m] 0.17 0.36 image current heat PIC [W/m] 0.15 0.33 0.78 gas-s. 100 h (10 h) tb Pgas [W/m] 0.04 (0.38) 0.06 (0.56) 0.09 (0.9) extent luminous region sl [cm] 4.3 3.7 5.3 comment D0 + crab crab wire comp. full crab crossing (FCC) large Piwinski angle (LPA) early separation (ES)

staged approach to LHC upgrade “phase-1” 2013: new triplets, D1, TAS, b*=0.25 m in IP1 & 5, reliable LHC operation at ~2x luminosity; beam from new Linac4 “phase-2” 2017: target luminosity 10x nominal, possibly Nb3Sn triplet & b*~0.15 m complementary measures 2010-2017: e.g. long-range beam-beam compensation, crab cavities, new/upgraded injectors, advanced collimators, coherent e- cooling, e- lenses longer term (2020?): energy upgrade, LHeC,… + injector upgrade phase-2 may be phase-1 + complementary measures!

LHC-CC08 Statistics mini-workshop held at BNL 25-26 February jointly organized by Ilan Ben-Zvi (Chair, BNL), Rama Calaga (LARP), Frank Z. (HHH) ~30 participants (limited by organizers) 5 CERN (R. Assmann, K.-H. Mess, R. Tomas, J. Tuck- mantel, F. Zimmermann); 4 KEK, 2 SLAC, 1 ANL, 2 LBNL, 3 FNAL, 1 AES, 4 JLAB, 6 BNL, 1 Tech-X, 3 CI (UK), 1 Cornell, 1 DESY, 1 INFN 27 presentations, >7 rounds of discussion web site: LHC crab TWiki: indico.cern.ch/conferenceDisplay.py?confId=24200 twiki.cern.ch/twiki/bin/view/Main/LHCCrabCavities

Sessions & Speakers introduction and overview (convener F. Zimmermann/CERN) I. Ben-Zvi. R. Palmer, R. Calaga, M. Cole optics & LHC integration (convener K. Oide/KEK) R. Tomas, R. Assmann, Y. Morita, J. Tuckmantel crab-cavity noise effects (convener A. Seryi/SLAC) K. Oide, K. Ohmi design, fabrication & processing (conv. H. Padamsee/Cornell) K. Hosayama, L Turlington, P. Kneisel, H. Wang other crab-cavity R&D in the world (convener I. Ben-Zvi/BNL) A. Seryi, P. McIntosh, A. Nassiri, F. Marcellini impedance issues (convener R. Rimmer/JLAB) C. Montag, Z. Li, G. Burt rf control (convener P. McIntosh/Daresbury) D. Li, A. Dexter, S. Simrock discussion & work packages (conv. R. Calaga/LARP+BNL) F. Zimmermann, R. Calaga

History & Ideas Bob Palmer – crab-cavity inventor & first workshop speaker crab cavities – first proposed by Bob Palmer for LC, Snowmass1988 crab cavities in storage rings proposed by K. Oide and K. Yokoya, one year later in 1989 (almost 20 years passed before first implementation in KEKB) Bob Palmer also invented 2-in-1 magnet revived & combined idea of “crab super disruption”

Key Points KEKB experience crucial R&D plan for LHC crab cavities (R&D on couplers, noise issues, impedance, collimation, beam- beam,…) staged approach: (1) prototype construction [SBIR] through 2010 (2) “global” crab cavity test in IR4 ~2011 (3) “local” crab cavities in IR1 & IR5 after LHC phase 1 upgrade international collaboration

KEKB: Global CC in rings Global Crab Scheme K. Oide KEKB: Global CC in rings implemented at KEKB could be fit into LHC IR4 (largest separation, infrastructure) could degrade LHC cleaning efficiency, especially for b*~0.25 m

Yi-Peng Sun & Ralph Assmann Collimation Issue set-up errors of collimators and transient changes of beam: magnitude: ~ 0.3 s (60 mm) off-momentum beta beat mixes up the 6D phase space and can corrupt collimation performance (e.g. loss of horizontal retraction for tertiary tungsten collimators): tertiary collimators (margin 0.8 s): ~ 0.5 s absorbers (margin 2.5 s): ~ 1.5 s global crab cavity further reduces aperture margin: estimate: ongoing, in the order ~ 0.5 s Nominal LHC - 0.5 sx off-momentum beta beating must be fixed before installing global crab cavities! (solution in progress for nominal LHC and upgrade phase 1, by S. Fartoukh) - 0.5 sx Yi-Peng Sun & Ralph Assmann

Local Crab Scheme requires more cavities Rama Calaga requires more cavities space constraints (transverse & longitudinal) could profit from / only possible with s.c. D1 noise tolerances may be easier should have little impact on collimation

LHC Crab Voltages 800 MHz Rama Calaga

R&D Collaboration I. Ben-Zvi most valuable asset : KEK experience; we should strive to add in areas unique to the LHC borrow ILC experience for simulations, modeling, couplers etc. various cavity shapes, couplers, tuners & cryostat designs deve- loped by various efforts around the world → cut design time powerful simulations codes & expertise in various laboratories R. Calaga

LHC-CC08 Conclusions phased crab cavity program for LHC need for correcting off-momentum b-beating in LHC crab cavities decoupled from the rest of LHC upgrade; they would boost luminosity for all LHC stages global collaboration, synergy with ILC, CLIC & light sources first prototype beam test expected approximately in 2011-2012 KEKB experience critical new coupler designs for robust damping needed collimation, impedance and noise issues require simulations, tests, and developments LHC would benefit from novel compact cavities

Deflecting Cavity Workshop ICFA Beam Dynamics Mini-Workshop on Deflecting/Crabbing Cavity Applications in Accelerators April 23-25, 2008 at SINAP, Shanghai   Topics: deflecting/crabbing cavity R&D in the applications of: high energy colliders (ILC, LHC, KEK-B, CLIC, …) generation of short x-ray pulse in synchrotron light sources beam manipulations, emittance exchanges and diagnostics http://www.sinap.ac.cn/ICFA2008/index.htm Yi-Peng Sun will represent HHH HHH LHC crab cavity day at CERN planned in fall’08