ATF2: the linear collider final focus prototype at KEK - an international telescope for nanometre size beams - Philip Bambade Laboratoire 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 e  e  linear colliders KEKB  superKEKB Photon Factory: science with photons + plans intense laser physics

Accelerator Test KEK  x = nm  y ~ 4-10 pm ATF2 final focus Damping Ring S-band Linac  x =  m  y = nm

LLR LAPP

Higgs boson production at threshold Proposal 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 230GeV 350GeV mHmH LAL F. Richard et al.

Higgs boson reconstruction at threshold gggg Detailed full MC simulation studies being performed with both Z   +  -, e+e- channels Improving 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-1 m H = 120 GeV Preliminary result with  channel : m H = ± GeV (model independent) Reconstructed spectra for different beam energies – includes realistic scaling of  IP to maintain collimation depth LHC : L=30 fb -1  m H =120 ± 0.2 GeV

Test FacilityDeliverableDate Hardware development, Optics and stabilisation demonstrations: ATF Demo. of reliable operation of fast kickers meeting the specifications for the ILC damping ring Generation of  y = 1 pm-rad emittance beam < ILC&CLIC spec ATF2 Demo. of compact Final Focus optics (design demagnification, resulting in a nominal 35 nm beam size at focal point) Demo. of prototype SC and PM final doublet magnets2012 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) Achieve lower emittance beams. Meas. of e-cloud build up in wiggler chambers Characterisation of e-cloud build-up and instability thresholds as a func. of low vertical emittance (≤20 pm) 2010 DAΦNEFast kicker design and pulser reliability check2010 Characterisation of e-cloud build-up and instability thresholds2010 SLAC/LLNLFast kicker pulser development2010 R&D deliverables from Test Facilities for ILC BDS and DR 15 successful in Oct !  y ~4-10 pm

ATF meets ILC normalised emittance challenge Horizontal & vertical emittances at present & planned electron rings

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ATF2 R&D for linear colliders  efficiency P elec N e E cm  x  y  efficiency P elec  beamstrahlung E cm  y,normalised Luminosity ~  Parameters ATF2ILCCLIC Beam Energy [GeV] L* [m]  x/y [m.rad] 5E-6 / 3E-81E-5 / 4E-86.6E-7 / 2E-8 IP  x/y [mm] 4 / / / 0.07 IP  ’ [rad]  E [%] ~ 0.1 ~ 0.3 Chromaticity ~ 1E4 ~ 5E4 Number of bunches1-3 (goal 1)~ Number of bunches3-30 (goal 2)~ Bunch population1-2E102E103.7E9 IP  y [nm] linac RF + sources beam size control & 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 system 2. Instrumentation for nano-beams 3. 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 nm at focal point - intra-train feedback (ILC-like trains) ATF2 COST : ~ M$ shared by Asia, EU, US

ATF2 operation & instrumentation R&D DR extraction setup, stability Match optics into FF buffer section for input errors 2 nd order telescope fine tuning of local errors

Daily operation meeting in control room 25

Commissioning periods Dec  3 weeks 2009  21 weeks (= ) Jan. – Jun  14 weeks (= ) 1 st cont. week Autumn 2010  7 weeks (=2+2+3) 2 nd continuous week Beam time scheduling 50% fraction for ATF2 & 4 days per week operation Individual RD tasks & common goals KEK, KNU, Tokyo, Sendai, SLAC, IHEP, UK, France, Spain, CERN,… ATF2 educational function Several 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 2009March 2009 nominal value  y = m  x = m since january 2010  y = m  x = 0.04 m 10 times nominal values ultra-low  upgrade factors 2-4 ultra-low  upgrade nominal  y nominal  x  2.5 Now

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.  f RF [kHz] = off 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 diagnostics 11. Horizontal IP re-matching (if required) 12. Vertical IP diagnostics 13. 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 1 st ATF2 continuous tuning run

Automated IP waist scans & Twiss measurements

Multiknobs for,,, and control Example with 3 FFS quads for x&y waists and hor. disp. Setup with laser wire-scanners   k      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 1 st and 2 nd ATF2 continuous beam tuning run in May & December  Need to plan and support set of regular “goal 1 dedicated” shift blocks for success in 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  R&D for ILC (and CLIC) 1. Continued ILC/CLIC R&D 2. Physics with intense laser not funded, to be reviewed T. Tauchi

Additional slides

 Technical design phased to  Also developing CLIC  ILC Main parameters E cm 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

DayOwl ShiftDay ShiftSwing Shift MON[2[2] Araki / Miyoshi [2[2,3] Kubo / Akagi Woodley,Edu3 TUE[3[3,4] Hayano / Kim White4 [5[5,6] Furuta / Bambade White, Nelson, Edu, Bambade6 [6[6,7,8] Omori / Woodley Wang, Seryi, Bolzon, Jones78 WED[7[7,8] Okugi / Shimizu White, Edu, Wang, Jones8 [8[8,9] Mitsuhashi / White Bambade, Nelson, Kamiya, Yamaguchi9 [10[10,11,(14)] Terunama / Bolzon Woodley, Seryi, Oroku, Edu1114 THURS[12[12,13,(14)] Fukuda / Sugiyama Woodley, Wang, Jones, Yamaguchi1314 [15[15,16] Toge / Aryshev Okugi, Neslon, Bambade, Jones, Kamiya, Edu16 [15[15,16] Naito / Abhay Seryi, White, Bolzon, Oroku, Tauchi16 FRI[15[15,16] Kuroda / Kurihara Woodley, Edu, Wang, Kamiya16 [15[15,16] Sato / Oroku Okugi, White, Nelson, Bambade, Jones, Oroku16 [15[15,16] Okugi / Yamaguchi White, Bolzon, Seryi, Jones, Yamaguchi16 1 st 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