ATF2: the linear collider final focus prototype at KEK
- an international telescope for nanometre size
beams -
Philip BambadeLaboratoire de l’Accélérateur Linéaire
Université Paris 11, Orsay, France
Seminar at Wayne State University, Michigan 11 January 2011
KEK High Energy Accelerator Research Organization, Tsukuba site, Japan
STF + ATF : R&D for future high energy ee linear colliders
KEKB superKEKB
Photon Factory: science with photons
+ plans intense laser physics
Accelerator Test Facility @ KEK
x = 1.2-2 nm y ~ 4-10 pm
ATF2 final focus
Damping Ring
S-band Linac
x = 2.8-10 m y = 20-50 nm
LLR
LAPP
Higgs boson production at thresholdProposal to run near threshold (√s=230GeV) for a light Higgs (120GeV)
Reason Higgs mass resolution determined from Higgs-strahlung process e+e- HZ (Z +-, e+e-) with the recoil mass method:
is the best due to - better momentum resolution of m±, e± at low energy - larger cross section at 230GeV than at e.g. 350GeV
2 2 2H Z Zm s m E s
230GeV
350GeV
mH
LAL 07-03 F. Richard et al.
Higgs boson reconstruction at threshold
gggg
Detailed full MC simulation studies being performed with both Z+-, e+e- channelsImproving previous studies with - optimal beam energy choice - realistic beamstrahlung effect (parameterization full simulation) - more efficient e / ID - better background rejection - model independent analysis (not using H decay final state & e / isolation)
√s = 230 GeV L = 500 fb-1mH = 120 GeV
Preliminary result with channel :mH = 120.010 ± 0.036 GeV (model independent)
Reconstructed spectra for different beam energies – includes realistic scaling of IP
to maintain collimation depth
LHC : L=30 fb-1 mH=120 ± 0.2 GeV
Test Facility Deliverable Date
Hardware development, Optics and stabilisation demonstrations:
ATFDemo. of reliable operation of fast kickers meeting the specifications for the ILC damping ring.
2010
Generation of y = 1 pm-rad emittance beam < ILC&CLIC spec. 2009
ATF2
Demo. of compact Final Focus optics (design demagnification, resulting in a nominal 35 nm beam size at focal point).
2010
Demo. of prototype SC and PM final doublet magnets 2012
Stabilisation of 35 nm beam over various time scales. 2012
Electron cloud mitigation studies:
CESR-TA
Re-config. (re-build) of CESR as low-emittance e-cloud test facility. First meas. of e-cloud build-up using instrumented sections in dipoles and drifts sections (large emittance).
2008
Achieve lower emittance beams. Meas. of e-cloud build up in wiggler chambers.
2009
Characterisation of e-cloud build-up and instability thresholds as a func. of low vertical emittance (≤20 pm)
2010
DAΦNE Fast kicker design and pulser reliability check 2010
Characterisation of e-cloud build-up and instability thresholds 2010
SLAC/LLNL Fast kicker pulser development 2010
R&D deliverables from Test Facilities for ILC BDS and DR
15
successful in Oct. 2009 !
y ~4-10 pm
ATF meets ILC normalised emittance challenge
Horizontal & vertical emittances at present & planned electron rings
17
ATF2 R&D for linear colliders efficiency Pelec Ne
Ecm x y
efficiency Pelec beamstrahlung
Ecm y,normalised
Luminosity ~
Parameters ATF2 ILC CLICBeam Energy [GeV] 1.3 250 1500
L* [m] 1 3.5 - 4.5 3.5
x/y [m.rad] 5E-6 / 3E-8 1E-5 / 4E-8 6.6E-7 / 2E-8
IP x/y [mm] 4 / 0.1 21 / 0.4 6.9 / 0.07
IP ’ [rad] 0.14 0.0094 0.00144
E [%] ~ 0.1 ~ 0.1 ~ 0.3
Chromaticity ~ 1E4 ~ 1E4 ~ 5E4
Number of bunches 1-3 (goal 1) ~ 3000 312
Number of bunches 3-30 (goal 2) ~ 3000 312
Bunch population 1-2E10 2E10 3.7E9
IP y [nm] 37 5.7 0.7
linac RF+ sources
beam sizecontrol & stability
cost &
feasibility
trade-off
ATF2 = scaled ILC & CLIC final focus new local chromaticity correction
P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)
Goal A : nanometer beam size - obtain y ~ 35 nm at focal point - reproduce reliably y ,maintain in time
1. Expert training on real system2. Instrumentation for nano-beams3. Accelerator RD & operation by multi-partner collaboration
• 2008 construction & installation• 2009 / 2010 commissioning• 2011 / 2012 goals 1 & 2 + instr. R&D• after 2013 continue Linear Collider R&D + new science projects with intense laser
ATF2 final focus prototype Goal B : trajectory stabilization - 1-2 nm at focal point - intra-train feedback (ILC-like trains)
ATF2 COST : ~ 3 + 1 M$ shared by Asia, EU, US
ATF2 operation & instrumentation R&D
DR extraction setup, stability
Match optics into FFbuffer section for input errors
2nd order telescopefine tuning of local errors
Daily operation meeting in control room
25
Commissioning periodsDec. 2008 3 weeks
2009 21 weeks (=1+2+4+3+3+1+2+2+3)
Jan. – Jun. 2010 14 weeks (=3+2+2+3+2+1+1) 1st cont. week
Autumn 2010 7 weeks (=2+2+3) 2nd continuous week
Beam time scheduling 50% fraction for ATF2 & 4 days per week operation
Individual RD tasks & common goalsKEK, KNU, Tokyo, Sendai, SLAC, IHEP, UK, France, Spain, CERN,…
ATF2 educational functionSeveral PhD & young post-doc researchers in accelerator science
Commissioning gradual x,y* (demagnification) reduction paced by
instrumentation (BSM / other) background studybeam tuning
Variable IP at ATF2
y [m]
April - December 2009 March 2009
nominal valuey = 0.0001 mx = 0.004 m
since january 2010
y = 0.001 mx = 0.04 m
10 times nominal values
ultra-low upgrade factors 2-4
ultra-low upgrade
nominal y
nominal x 2.5Now
Instrumentation preparation and R&D
• Stripline BPMs, C and S band cavity BPMs, BSM “Shintake”, wire-scanners
in most part commissioned and operating satisfactorily (few improvements underway)
• IP-cavity BPMs, tilt monitor, OTR profile, LW, FONT
actively studied as R&D in preparation for goal 2 (and 1)
• Background monitors: PLIC optical fibre + dedicated instrumentation
simulation effort coupled to measurements needed to assess ultra low * feasibility
Reconstructing variations at injection(during dispersion measurements)
Y. Renier et al.
fRF [kHz] = off 0 +3 +2 +1 0 -1 -2 -3 -2 -1 0 +1 +2 +3 off
Measure X dispersion by changing DR energyX dispersion from energy fluctuations
Y. Renier et al.
DR IP
Y dispersion from energy fluctuations < 1e-4
“Shintake” beam size monitor at IP
Sensitivity ranges of crossing angles
1. Startup 2. DR tuning 3. EXT & FFS C-band BPM calibration 4. FFS S-band BPM calibration 5. Initial EXT & FFS setup 6. EXT dispersion measurement and correction (x & y) 7. EXT Twiss + emittance calculation at IEX match point (x & y) 8. EXT coupling correction 9. IPBSM preparation 10. Horizontal IP diagnostics11. Horizontal IP re-matching (if required)12. Vertical IP diagnostics13. Vertical re-matching (if required)14. FFS Model diagnostics (if required)15. IP multiknob tuning with IPBSM vertical beam size mode - IP y waist, dispersion, coupling scans - IP x waist, dispersion scans - Higher-order terms with dK / tilts
16. IPBSM study - Study required at changeover points between crossing modes - 2/8 degree mode >~350nm - 100nm ~< 30 degree mode ~< 350nm
Tuning steps for 1st ATF2 continuous tuning run
Automated IP waist scans & Twiss measurements
Multiknobs for <xx’>, <yy’>, <yx’>, <xE> and <yE > control
Example with 3 FFS quadsfor x&y waists and hor. disp.
Setup with laserwire-scanners k <yx’> <yx’> k tuning
+ systematics…
Conclusions and prospects• ATF = only fully open facility for R&D in accelerator physics and instrumentation
• International training of young Post-Docs, PhD and Master students, many through co-supervision
• Excellent progress with beam instrumentation, especially BPMs (striplines and cavities), BSM and several other ATF2 R&Ds
• 1st and 2nd ATF2 continuous beam tuning run in May & December
Need to plan and support set of regular “goal 1 dedicated” shift blocks for success in 2011
• 300 nm vertical spot (target ~ 100 nm)
• ATF operation guaranteed for dedicated LC R&D guarantied to end 2012 – program should continue for LC and extend to other science goals (e.g. strong field physics with intense laser) beyond
Tentative research schedule for 2010-2015 R&D for ILC (and CLIC)
1. Continued ILC/CLIC R&D 2. Physics with intense lasernot funded, to be reviewed
T. Tauchi
Additional slides
Technical design phased to 2010-2012 Also developing CLIC ILC
Main parameters
• Ecm adjustable from 200 – 500 GeV
• Luminosity ∫Ldt = 500 fb-1 in 4 years
• Ability to scan between 200 and 500 GeV
• Energy stability and precision below 0.1%
• Electron polarization of at least 80%
• The machine must be upgradeable to 1 TeV
Present outlook
Day Owl Shift Day Shift Swing Shift
MON [2]Araki / Miyoshi
[2,3]Kubo / AkagiWoodley,Edu
TUE [3,4]Hayano / KimWhite
[5,6]Furuta / BambadeWhite, Nelson, Edu, Bambade
[6,7,8]Omori / WoodleyWang, Seryi, Bolzon, Jones
WED [7,8]Okugi / ShimizuWhite, Edu, Wang, Jones
[8,9]Mitsuhashi / WhiteBambade, Nelson, Kamiya, Yamaguchi
[10,11,(14)]Terunama / BolzonWoodley, Seryi, Oroku, Edu
THURS [12,13,(14)]Fukuda / SugiyamaWoodley, Wang, Jones, Yamaguchi
[15,16]Toge / AryshevOkugi, Neslon, Bambade, Jones, Kamiya, Edu
[15,16]Naito / AbhaySeryi, White, Bolzon, Oroku, Tauchi
FRI [15,16]Kuroda / KuriharaWoodley, Edu, Wang, Kamiya
[15,16]Sato / OrokuOkugi, White, Nelson, Bambade, Jones, Oroku
[15,16]Okugi / YamaguchiWhite, Bolzon, Seryi, Jones, Yamaguchi
1st ATF2 continuous tuning run May 17-21, 2010
Software tasks organized following “HEP experiment” model
2 environments: Original ATF V-System + appl. software
Flight Simulator portable control system
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