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