“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)  

HHHHHHHHHHHH

HHHHHHHHHHHHCrab PotentialCrab Potential

analytical formula

tracking with Guinea-Pig

Y.-P. Sun

Name Event DateName Event Date33

Reminder: LHC upgrade pathsReminder: LHC upgrade paths

• ultimate beam (1.7x10ultimate beam (1.7x101111 protons/bunch, 25 spacing), protons/bunch, 25 spacing), * ~10 cm * ~10 cm

• early-separation dipoles in side detectors , crab cavities early-separation dipoles in side detectors , crab cavities

→ → hardware inside ATLAS & CMS detectors, hardware inside ATLAS & CMS detectors,

first hadron crab cavities; off-first hadron crab cavities; off-

stronger triplet magnets

D0 dipole

small-angle

crab cavity

J.-P. Koutchoukearly separation (ES)early separation (ES)

stronger triplet magnets

small-angle

crab cavity

• ultimate LHC beam (1.7x10ultimate LHC beam (1.7x101111 protons/bunch, 25 spacing) protons/bunch, 25 spacing)

• * ~10 cm * ~10 cm

• crab cavities with 60% higher voltage crab cavities with 60% higher voltage

→ → first hadron crab cavities, off-first hadron crab cavities, off--beat-beat

L. Evans,W. Scandale,F. Zimmermann

full crab crossing (FCC)full crab crossing (FCC)

wire

compensator

larger-aperture triplet magnets

• 50 ns spacing, longer & more intense bunches 50 ns spacing, longer & more intense bunches

(5x10(5x101111 protons/bunch) protons/bunch)

• *~25 cm, no elements inside detectors*~25 cm, no elements inside detectors

• long-range beam-beam wire compensation long-range beam-beam wire compensation

→ → novel operating regime for hadron novel operating regime for hadron colliders, colliders,

beam generationbeam generation

F. Ruggiero,W. Scandale.F. Zimmermann

large Piwinski large Piwinski angle (LPA)angle (LPA)

parameter symbol nominal ultimate Early Sep. Full Crab Xing L. Piw Angle

transverse emittance [m] 3.75 3.75 3.75 3.75 3.75

protons per bunch Nb [1011] 1.15 1.7 1.7 1.7 4.9

bunch spacing t [ns] 25 25 25 25 50

beam current I [A] 0.58 0.86 0.86 0.86 1.22

longitudinal profile Gauss Gauss Gauss Gauss Flat

rms bunch length z [cm] 7.55 7.55 7.55 7.55 11.8

beta* at IP1&5 [m] 0.55 0.5 0.08 0.08 0.25

full crossing angle c [rad] 285 315 0 0 381

Piwinski parameter cz/(2*x*) 0.64 0.75 0 0 2.0

hourglass reduction 1 1 0.86 0.86 0.99

peak luminosity L [1034 cm-2s-1] 1 2.3 15.5 15.5 10.7

peak events per #ing 19 44 294 294 403

initial lumi lifetime L [h] 22 14 2.2 2.2 4.5

effective luminosity (Tturnaround=10 h)

Leff [1034 cm-2s-1] 0.46 0.91 2.4 2.4 2.5

Trun,opt [h] 21.2 17.0 6.6 6.6 9.5

effective luminosity (Tturnaround=5 h)

Leff [1034 cm-2s-1] 0.56 1.15 3.6 3.6 3.5

Trun,opt [h] 15.0 12.0 4.6 4.6 6.7

e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) 1.04 (0.59) 1.04 (0.59) 0.36 (0.1)

SR heat load 4.6-20 K PSR [W/m] 0.17 0.25 0.25 0.25 0.36

image current heat PIC [W/m] 0.15 0.33 0.33 0.33 0.78

gas-s. 100 h (10 h) b Pgas [W/m] 0.04 (0.38) 0.06 (0.56) 0.06 (0.56) 0.06 (0.56) 0.09 (0.9)

extent luminous region l [cm] 4.5 4.3 3.7 3.7 5.3

comment nominal ultimate D0 + crab crab wire comp.

larg

e P

iwin

ski angle

(LP

A)

full

crab c

ross

ing (

FCC

)

earl

y se

para

tion (

ES)

staged approach to LHC upgrade staged approach to LHC upgrade “phase-1” 2013:

new triplets, D1, TAS, *=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 & *~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,…phase-2 may be phase-1 + complementary measures!

+ injector upgrade

HHHHHHHHHHHHLHC-CC08 StatisticsLHC-CC08 Statistics• mini-workshop held at mini-workshop held at BNL 25-26 FebruaryBNL 25-26 February

• jointly organized by jointly organized by Ilan Ben-Zvi Ilan Ben-Zvi (Chair, BNL), (Chair, BNL), Rama Calaga Rama Calaga (LARP), (LARP), Frank Z. Frank Z. (HHH)(HHH)

• ~30 participants (limited by organizers)~30 participants (limited by organizers)

• 5 CERN 5 CERN (R. Assmann, K.-H. Mess, R. Tomas, J. Tuck- (R. Assmann, K.-H. Mess, R. Tomas, J. Tuck- mantel, F. Zimmermann); mantel, F. Zimmermann); 4 KEK, 2 SLAC, 1 ANL, 4 KEK, 2 SLAC, 1 ANL, 2 LBNL, 3 FNAL, 1 AES, 4 JLAB, 6 BNL, 1 2 LBNL, 3 FNAL, 1 AES, 4 JLAB, 6 BNL, 1 Tech-X, 3 CI (UK), 1 Cornell, 1 DESY, 1 INFN Tech-X, 3 CI (UK), 1 Cornell, 1 DESY, 1 INFN

• 27 presentations, >7 rounds of discussion27 presentations, >7 rounds of discussion

• web site:web site:• LHC crab TWiki:LHC crab TWiki:

indico.cern.ch/conferenceDisplay.py?confId=24200

twiki.cern.ch/twiki/bin/view/Main/LHCCrabCavities

HHHHHHHHHHHHSessions Sessions && SpeakersSpeakersI. introduction and overview (convener F. Zimmermann/CERN) I.

Ben-Zvi. R. Palmer, R. Calaga, M. Cole

II. optics & LHC integration (convener K. Oide/KEK) R. Tomas, R. Assmann, Y. Morita, J. Tuckmantel

III.crab-cavity noise effects (convener A. Seryi/SLAC) K. Oide, K. Ohmi

IV.design, fabrication & processing (conv. H. Padamsee/Cornell) K. Hosayama, L Turlington, P. Kneisel, H. Wang

V. other crab-cavity R&D in the world (convener I. Ben-Zvi/BNL) A. Seryi, P. McIntosh, A. Nassiri, F. Marcellini

VI. impedance issues (convener R. Rimmer/JLAB) C. Montag, Z. Li, G. Burt

VII. rf control (convener P. McIntosh/Daresbury) D. Li, A. Dexter, S. Simrock

VIII. discussion & work packages (conv. R. Calaga/LARP+BNL) F. Zimmermann, R. Calaga

HHHHHHHHHHHH

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 firstimplementation in KEKB)

Bob Palmer also invented2-in-1 magnet

revived & combined idea of “crab super disruption”

History & IdeasHistory & IdeasBob Palmer – crab-cavity inventor & first workshop speaker

HHHHHHHHHHHH

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

Key PointsKey Points

HHHHHHHHHHHHGlobal Crab SchemeGlobal Crab Scheme

• implemented at KEKB• could be fit into LHC IR4 (largest separation, infrastructure) • could degrade LHC cleaning efficiency, especially for *~0.25 m

KEKB: Global CC in rings

K. Oide

HHHHHHHHHHHHCollimation IssueCollimation Issue• set-up errors of collimators and transient changes of beam:

– magnitude: ~ 0.3 (60 m)

• off-momentum beta beat mixes up the 6D phase spacemixes up the 6D phase space and can corrupt collimation performancecorrupt collimation performance (e.g. loss of horizontal retraction for tertiary tungsten collimators):– tertiary collimators (margin 0.8 ): ~ 0.5 – absorbers (margin 2.5 ): ~ 1.5

• global crab cavity further reduces aperture margin:– estimate: ongoing, in the order ~ 0.5

• 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)

Yi-Peng Sun & Ralph Assmann

- 0.5 xNominal LHC

- 0.5 x

HHHHHHHHHHHHLocal Crab SchemeLocal Crab Scheme

• 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

Rama Calaga

HHHHHHHHHHHHLHC Crab VoltagesLHC Crab Voltages

Rama Calaga

800MHz

HHHHHHHHHHHH

R. Calaga

R&D CollaborationR&D Collaboration• 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

I. Ben-Zvi

HHHHHHHHHHHHLHC-CC08 ConclusionsLHC-CC08 Conclusions

1. phased crab cavity program for LHC

2. need for correcting off-momentum -beating in LHC

3. crab cavities decoupled from the rest of LHC upgrade; they

would boost luminosity for all LHC stages

4. global collaboration, synergy with ILC, CLIC & light sources

5. first prototype beam test expected approximately in 2011-2012

6. KEKB experience critical

7. new coupler designs for robust damping needed

8. collimation, impedance and noise issues require simulations,

tests, and developments

9. LHC would benefit from novel compact cavities

HHHHHHHHHHHHDeflecting Cavity WorkshopDeflecting Cavity WorkshopICFA 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