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“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