A_RD_2 Collaboration on ATF2 final focus prototype and MDI for future linear colliders ILC & CLIC Philip Bambade LAL & KEK On behalf of colleagues from KEK, Saga & Tohoku U., LAL, LAPP and LLR FJPPL’09 Tsukuba May 20-21, 2009

ATF2 final focus KEK Goal A : nanometer beam size - obtain  y ~ 35 nm at focal point - reproduce reliably  y and maintain in time Goal B : trajectory stabilization nm at focal point - intra-train feedback (ILC-like trains) 1. Expert training on real system 2. Instrumentation for nano-beams 3. Accelerator RD & operation by multi-partner collaboration 2008 end construction & installation December 2008 first beams commissioning COST : ~ M$  Asia, EU, US  x = 1.2 nm  y ~12 (5) pm

ATF2 = scaled version of ILC & CLIC final focus  test new local chromaticity correction scheme

Final Doublet mechanical support Integrated vibration evaluation LAPP LLR Beam background study LAL Beam tuning algorithm Commissioning organization KEK Beam tuning algorithm BSM mech. support Infrastructure & support Management

LAPP: Mechanical support & stability of FD, Commissioning Vibration characterization & modeling in full ATF2 line A. Jérémie, G. Gaillard, N. Geffroy B. Bolzon  continued as ANR post-doc LLR: Background evaluation (algorithm, GEANT4) Instrumentation & experimentation for validation M. Verderi, H. Guler (ANR post-doc) LAL: Beam tuning & control, software tools, computing Commissioning strategy & organization P. Bambade, G. Le Meur, C. Rimbault, F. Touze Y. Rénier, M. Alabau (Valencia), S. Bai (IHEP) + ANR post-doc (2009) KEK: BSM incl. mechanical support, beam tuning strategy Infrastructure, host & direct partner in all activities T. Tauchi, T. Kume, S. Kuroda, T. Okugi, R. Sugahara, J. Urakawa Collaborations: UK, SLAC, CERN, IHEP, Valencia FJPPL contribution to ATF2 (ANR )

Present ATF2 status Construction & installation mostly completed end of 2008 First beam at dump for radiation inspection in Dec Hard- / software commissioning in Feb. & Mar Optical injection match & IP correction in Apr. & May 2009 ( this slide has been shown unchanged since 2006 )  gradually reducing optical demagnification towards design value

LAPP : Final Doublet supports mechanical stability & integration

Ground Shintake monitor Final doublet Beam Interference fringes We want the measurement to have a coherent behaviour with respect to the “beam” => Relative motion between Shintake monitor and final doublets: 6-7nm in the vertical axis above 0.1Hz 4m Good ground motion coherence: measured on KEK site  Separate stiff supports rigidly fixed to the floor for Shintake monitor and final doublet Back to basics : specifications  Study the CLIC honeycomb block but without its active feet With Shintake monitor and final doublet on separate supports with active stabilization  coherence is lost

Don’t support block on 4 feet fix to floor on entire base Experimental set-up 3 steel plates bolted to the floor Honeycomb table Bees wax  Good boundary conditions chosen for the block: Relative motion should be very low compared to tolerances No masses: no peak With masses: 92Hz

IP QD0 SF1 QF1 SD0 Room for slings Final assembly Quads, sextupoles and movers :SLAC (from FFTB) From floor to mover: LAPP (new) BPM + support: KNU, LAPP 2.4m Adjustment possible in x, y, z with shims (0.05mm) and adjustment pushers for 1.2m beam height Beeswax : good vibration transmission easy to unglue & stable in time & radiation hard

SBPM QC3 SBPM FFTB 2.13 S3.00 SF1FF QF1FF SBPM QC3 SBPM FFTB 2.13 S3.00 SD0FF QD0FF Sweeping Honda Shintake IP  Table=2400 Successfully shipped & installed after detailed mechanical integration design & stability studies done at LAPP

Vibration measurements after installation QD0  QF1  Shintake  floor ( all combinations, with & without water cooling ) Shintake Sensor QD0-Shintake : 4.4 nm QF1-Shintake : 6.3 nm Induced beam motion  less due to F / D compensation

Vibration measurement along entire ATF2 line  update of GM generator parameters Wave-like motion dominates for f > 0.1 Hz  Modeling possible with 3 waves, both with theoretical expression or using A. Seryi’s ground motion generator Example : fitting propagation velocity from correlation measurements

Application : Combined effect on IP beam of all quad. vibrations Gradual loss of coherence with increasing distance IP beam motion from each quad taking into account its optical lever arm ATF2 final focus  functions Integrated IP beam motion from final doublet  10 nm from all quads  14 nm  Lucky compensation between F/D quads and from optical phase advance

LLR : Beam-induced background measurements  modeling ( photons & neutrons )

Goals Simulation of beam halo loss along beam line 1. Validate GEANT4 / BDSIM beam line modeling tool with controlled measurements 2. Help minimize background in Shintake monitor Compton photon calorimeter 3. Neutrons and bremstrahlung photons

Use mobile, flexible & modular detector 45 cm 27 cm Scintillator (plastic or CsI) Photomultiplier Modules are assembled at will Radiator slabs (tungstene) can be inserted at any place Modules can be assembled off beam in desired configuration And then carried like a suitcase Modules for now : 2 plastic (60×60×38 mm) 1 CsI (60×60×20 mm) Acquisition = oscilloscope Module (side view) Assembly box (top view) Entrance window

Installation at KEK and first tests May 19

Detector box Record (x,y) position of muons Work going on to extract light collection as function of muon impact point on scintillator : measured muon trajectories will be used as input to the simulation to make a per-event estimation of the effect. Detailed calibrations: mips, neutrons, e- example: cosmic test lab. Cosmic bench test used at lab wich records impact points and direction of incident muons. Allows to measure unbiased mips for PM intercalibation, and absolute calibration wrt simulation.  detailed & quantitative background study & prediction for LC + other accelerators

LAL : Beam tuning & control commissioning strategy & organization

Concept of final focus tuning process BSM CAL DRMATCHEXT COL buffer to absorb input variations  emittance aperture (aberrations) bremstrahlung background  IP target Gradual demagnification (  x,y ) reduction  paced by progress with : beam tuning instrumentation (BSM / other) background study

Variable  IP at ATF2  y [m] April’09 target March’09 target nominal value (  y = m)

 Could magnets shared with damping ring be the cause of the effect ? Extraction line vertical emittance growth ?  Jan’09: QM7 exchanged for larger 42mm bore  Improves but only partial explanation: crucial to reproduce injection orbit

Present commissioning highlights (1) Vertical emittance ~ 20 pm reproduced 3 successive weeks  Careful injection orbit setup, dispersion and coupling corrections  Automation essential to speed up : 6 skew quads + 5 wire scanners

Present commissioning highlights (2) 1) Angular div. & emittance   y ~ 1-2 cm close to target value 2) Infer  y ~ 0.5 micron at minimum, but measure ~ 2-3 micron betatron match ~ OK but need dispersion & coupling corrections dd

Software tasks organized at FJPPL ATF2 LAL Two environments: V-System & Flight Simulator

Commissioning periods May 2009  3 weeks October – December 2009  7 weeks January – June 2010  14 weeks October – December 2010  7 weeks ( extrapolation ) Beam time scheduling 50% fraction for ATF2 & 4 days per week operation Individual R&D tasks  common goal Groups: KEK, Tokyo, SLAC, IHEP, UK, France, Spain, CERN,… ATF2 educational function Several PhD & young post-doc researchers in accelerator science

Main priorities for May ° Shintake interference mode   y ~ 0.3 – 2  m reproducible EXT setup   y < 40 pm Oct – Dec (or 30) degree mode BSM   y ~ 100 nm Jan – Jun 2010 optimization of chromatically corrected tuned beam spot   y ~ 40 nm Oct – Dec 2010 reproducibility & stability first go at reduced  optics

1. B.Bolzon et al., Linear collider final doublet considerations: ATF2 vibration measurements 2. A.Seryi et al., ATF2 Commissioning 3. R.Tomas et al., ATF2 ultra-low IP betas proposal 4. T.Kume et al., Nanometer stabilization for precision beam size monitor (Shintake monitor) 5. T.Yamanaka et al., Status of the first commissioning of the Shintake monitor for ATF2 6. T.Scarfe et al., ATF2 Spot Size Tuning Using the Rotation Matrix Method 7. R. Apsimon et al., Beam test results with FONT4 ILC prototype intra-train beam feedback system 8. R. Apsimon et al., Development of a Fast Micron-Resolution Beam Position Monitor Signal Processor for Linear Collider Beam-Based Feedback Systems 9. J. Resta-Lopez et al., Design and Performance of Intra-train Feedback Systems at ATF2 10. M. Alabau et al., Study of the effect of the non-linear magnetic fields in the extraction region of the ATF Extraction Line on the emittance growth 11. D.Okamoto et al., Beam orbit tilt monitor studies at ATF2 12. A.Lyapin et al., Development of C-band BPM for ATF2 13. A.Lyapin et al., Development of S-band BPM for ATF2 14. G.White et al., Towards tuning the ATF2 Final Focus System to Obtain a 35nm IP Waist 15. S.Molloy et al., A Flight Simulator based Beam Based Alignment package for ATF2 16. S.Molloy et al., Using the Universal Accelerator Parser to allow the interfacing of third- party accelerator code with the Lucretia Flight Simulator 17. S.Bai et al., Beam waist manipulations at the ATF2 interaction point 18. Y.Renier et al., Orbit rec., correction, stabilization + monitoring in ATF2 extraction line 19. A.Aryshev et al., Micron size laser-wire system at ATF extraction line, recent results inc. ATF2 20. R. Tomas et al., Measurement of non-linear resonances in the ATF DR 21. B. Bolzon et al., LC test facility: ATF2 Final Doublet active stabilization pertinence PAC’09 (FJPPL contribution)

FJPPL A_RD_2 teams & request

Back-up slides

Is 37 nm vertical size the limit at ATF2 ? Study explores to what extent can be varied the   * Originally motivated to start ATF2 with larger   * values –More comfortable situation, less sensitive to errors (non-linear optics…) Study shows that beam size down to ~17 nm might be achievable ! –Of large interest for CLIC machine, to demonstrate the its chromaticity regime is feasible –Such low   * values are also of interest for alternative (more economical) ILC setups with “pushed” IP parameters

 Empty: 56.2Hz  with FD weight: 26.2Hz Study of the block on 4 feet (free-free configuration: 1st peak at 230Hz) In the middle of : 0.1Hz-100Hz! Simple simulation (plain block) Measurements Empty: 74Hz With FD weight: 46Hz  Can shift to higher frequency if block fixed on entire surface Total relative motion ([0.17; 100]Hz): 6.7nm  Above tolerances (6nm)! Contribution of the peak alone: [10; 100]Hz: 5.7nm

Update of GM model parameters for ATF2 Descriptio n NotationKEK B model ATF RingATF2 1st wave Frequencyf1 [Hz] Amplitudea1 [m^2/Hz]4.0* * * Widthd1 [1] Velocityv1 [m/s] nd wave Frequencyf2 [Hz] Amplitudea2 [m^2/Hz]3.0* * * Widthd2 [1] Velocityv2 [m/s]300 3rd wave Frequencyf3 [Hz] Amplitudea3 [m^2/Hz]3.0* * Widthd3 [1] Velocityv3 [m/s]250

Simulation tool Develop a simulation application Geant4-based which allows to easily change the detector configuration with macro files. –Of course, underneath Geant4 features, as to change the “physics list” for example, are used. Work going on to include PM/scintillator response to further compare with data. –ie : no calibration in subsequent plots here Detectors description will be interfaced with BDSIM. 100 MeV incoming e  ’s Incoming neutrons from Am/Be PM & mu-metalplastic Tungstene slabs CsI

Neutron test Saclay Am/Be neutron source 5×10 6 n/s Am/Be neutron source 5×10 6 n/s 1 m ~40 Hz/cm 1m Config. : plastic;plastic;CsI Detector box Config : plastic; plastic;CsI base line Beware this zone is biaised by trigger ! Polyethylene bricks added to moderate neutron Interest of Am/Be source : highest neutron energy comparable to that of neutrons from ATF2 beam dump. Full simulation of these data will require to simulate the effect of trigger/threshold.

e + beam DESY (1/2) We never get individual photon in background ATF2 –Always get a burst Measuring the energy deposit longitudinal profile may help to get information on photon spectrum –To further compare with simulation Sample the profile at: –1X 0 : more low E sensitive –4X 0 : mostly E insensitive : gets mean energy –10X 0 : more high E sensitive Mimic a particle burst by degrading incoming energy with some X 0 Simulation e±e±  Energy spectra after 3X 0 for incoming electron

e + beam DESY (2/2) Test beam dataSimulation e + beam Detector box 1X 0 plastic 3X 0 plastic 6X 0 CsI With 3X 0 in front to degrate incoming energy External trigger 1,2,3 GeV Suspect brem. here

Backup Simulation Test beam data

TOKIN 3581 quads available  new PRIAM 2D calc. extracted beam offset [m] K0L K2L X ext = 22.5 mm Radius Turns Max I Current needed: QM7 16mm A 130*(42/32)2*17/26= 146 A Q mm A  present PS system sufficient  K1L and K2L error almost disappears ! K1L ~ m -1 = 0.99  nominal ( previously = 0.76  nominal ) ~ 1 m -2 ( previously = 46.6 m -2 )

K0L K1L K2L TOKIN 3581 measurement TOKIN 3581 PRIAM simulation QM7 PRIAM simulation X extraction  22.5 mm R TOKIN = 21 mm R QM7 = 16 mm K1L = 0.99  nominal K2L = 1 m -2 K1L = 0.76  nominal K2L = 47 m -2

Lead block in front of the detector Lead block (5 cm × 3) in front of the detector Most of the fast part was decreased The delayed part was remained

Paraffin shield Concrete shieldParaffin The delayed background (neutron?) was suppressed after parrafin shield.

Length ~ 300 m dump(s): 0.5 m 3 m New “minimal” 2 mrad crossing-angle extraction ILC line concept QF, SF warm quad & sext QD, SD NbTi (Nb3Sn) SC FDFD 3 warm bends 2 “Panofsky” quads collimators |  Explicit goals : short & economical, as few and feasible magnets as possible, more tolerant and flexible Beam rastering kickers can be placed to prevent water boiling and window damage kickers BB1,2 BHEX1 Extraction line has been integrated with the FFS flexible

QEX1 modified “Panofsky”-style quad design Multipole expansion 6m Lumped multipole errors QEX1 Extra multipole field components modeled in DIMAD Disrupted beam tracking (500 GeV) along the extraction line with multipoles: –Power loss increase of 1kW at 1 collimator –Dump beam size increase of 5% Permanent magnet plates help reduce field to 10 Gauss for incoming beam