1. EMMA Design and Construction Bruno Muratori STFC, Daresbury Laboratory 21/01/09

2. The EMMA Project EMMA (Electron Machine with Many Applications) is a design for a non-scaling FFAG – the world’s first Collaboration of : BNL, CERN, CI, FNAL, JAI, LPSC Grenoble, STFC, TRIUMF Part of BASROC (British Accelerator Science and Radiation Oncology Consortium) / CONFORM (COnstruction of a Non-scaling FFAG for Oncology, Research and Medicine) Advantages: –Linear fixed field magnets: large dynamic aperture –Cheaper Disadvantages: –Novel longitudinal & transverse dynamics –Rapid tune variations: multiple resonance crossings Many potential applications –Driver for ADSR, µ acceleration, medical (e.g. PAMELA)

3. INJECTION LINE ALICE to EMMA New Dipoles x 2 (33°) & BPMs at dipole entrance Position measurement New Dipole 30° & BPMs at dipole entrance Position measurement BPM Position measurement Wall Current Monitor New Quadrupoles x 13 Ion Pump Vacuum valve Tomography Section Screens x 3 (emittance measurement) SRS Quadrupoles x 3 Screen & Vert. Slit Beam Direction SRS Quadrupoles x 2 Screen Vacuum valve Screen Emittance measurement Current measurement EMMA Ring ALICE Match the probe beam to the requirements of EMMA Measure the properties of the probe beam

4. Diagnostics – injection line OTR Screen in ALICE before extraction dipole BPMs @ entrance of every dipole in injection line Straight ahead Faraday cup to measure charge & energy spread OTR screen in dogleg for bunch length & energy measurement Tomography section: 60 degrees phase advance per screen with three screens for projected transverse emittance measurements and profiles Last dispersive section: –OTR screen & vertical slit in middle of first section together with –OTR screen in final section for energy and energy spread measurements –Vertical steerers for position & angle before ring (to be used with kickers for steering) –BPM at entrance of EMMA ring for position before entering

5. ALICE to EMMA injection line (2) Tomography diagnostics also used to better control beam Twiss parameters and dispersion and its derivative are different for every energy and have to be precise Different match for all energies (10-20 MeV) All matches achieved to good accuracy – wyaiwyg ‘what you ask is what you get’

6. Injection Septum 65° Kicker Cavities x 19 Extraction Septum 70° Kicker Screen Wire Scanner Wall Current Monitor Wire Scanner Screen BPM x 82 D Quadrupole x 42 F Quadrupole x 42 16 Vertical Correctors IOT Racks (3) Waveguide distribution EMMA Ring Kicker Power Supplies Septum Power Supply Septum Power Supply Kicker Power Supplies

7. 6 CELL Girder Assembly Ion Pump Cavity D Magnet F Magnet Location for diagnostics Beam direction Girder

8. 2 Cell Section (standard vacuum chamber) Cavity QD QF Vertical Corrector BPM 2 per cell Beam direction Bellows Standard vacuum chamber per 2 cells Field clamp plates Location for diagnostic screen and vacuum pumping

9. Injection & Extraction (1) Kicker Septum Cavity Injection Screen Injection scheme shown Extraction is Kicker, Kicker, Septum arrangement

10. Injection and Extraction (2) Have to match ‘orbits’ at all energy ranges & for all settings (10 – 20 MeV) –Kickers –Septum rotation & motion –In-house code (FFEMMAG - Tzenov) –Vertical & Horizontal steerers in injection line – also used for painting (3 mm rad acceptance) Kickers specified at 0.07 T

11. EMMA Kicker Magnet Fast Switching Magnet length0.1m Field at 10MeV (Injection)0.035T Field at 20MeV (Extraction)0.07T Magnet Inductance 0.25  H Lead Inductance 0.16  H Peak Current at 10/20MeV1.3kA Peak Voltage at Magnet14kV Peak Voltage at Power Supply 23kV Rise / Fall Time35nS Jitter pulse to pulse>2nS Pulse WaveformHalf Sinewave Kicker Magnet Power Supply parameters are directly affected by the compact design and require: Fast rise / fall times 35 nS Rapid changes in current 50kA/  S Constraints on Pre and Post Pulses Applied Pulse Power Collaboration Design and construction of thyristor prototype units using magnetic switching and Pulse Forming Network techniques

12. Injection and Extraction 133 mm internal 100 mm 25° 180 mm internal Final Parameters Large angle for injection (65°) and extraction (70°) very challenging !! Injection/Extraction scheme required for all energies 10 – 20 MeV, all lattices and all lattice configurations Minimise stray fields on circulating beam Space very limited between quadrupole magnet clamp plates

13. Septum Concept Motorised linear actuators external to vacuum Electrical feedthroughs (conductor path to power supply requires to be short to reduce inductance) Vacuum flange Aluminium wire seal Translation & rotation in-vacuum bearings Conductor connections with flexibility to feedthrough to accommodate septum movement Pole gap 25 mm Complete septum assembly mounted from top section of vacuum chamber lid. 2 linear actuators provide translation and rotation of septum. -7 to 15 mm 0 - 7°

14. Septum Design In house design of septum and vacuum chamber in progress Wire eroding of lamination stacks scheduled for February, steel delivered. Magnet measurements scheduled for April 09 Plan view of septum in vacuum chamber Section view of septum in vacuum chamber ISO view of septum with vacuum chamber removed

15. Cavity Design Normal conducting single cell re-entrant cavity design optimised for high shunt impedance Capacitive post tuner Probe Coolant channels Input coupling loop EVAC Flange Aperture Ø 40 mm 110 mm ParameterValue Frequency1.3 GHz Theoretical Shunt Impedance 2.3 M  Realistic Shunt Impedance (80%) 2 M  Qo (Theoretical) 23,000 (23000) R/Q100 Ω Tuning Range-4 to +1.6 MHz Accelerating Voltage120 kV180 kV Total Power Required (Assuming 30% losses in distribution 90 kW200 kW Power required per cavity 3.6 kW8.1 kW Cavity machined form 3 pieces and EB welded at 2 locations

16. ALICE EMMA SRS quadrupoles New quadrupoles TD Cavity spectrometer dipole Diagnostics / Extraction line

17. NEW DIAGNOSTICS BEAMLINE LAYOUT Spectrometer BPM @ dipole entrance Screen Faraday Cup E-O Monitor Screen x 3 Tomography Section Wall Current Monitor BPM & Valve SRS Quadrupoles x 6 New Quadrupoles x 4 ALICE New Dipoles (43°) & BPMs at dipole entrance Current measurementLongitudinal profile Position measurement New Quadrupoles x 4 Screen & Vert. Slit Emittance measurement Extracted momentum Location for Transverse Deflecting Cavity (NOT IN BUDGET) Screen

18. Diagnostic line deflecting cavitytomographyEO spectrometer

19. Measurements Energy –First dipole & spectrometer at end with OTRs Projected transverse emittance –Quadrupole scans & tomography 60° phase advance / screen –Equivalent set-up in injection line for comparisons Bunch length –EO monitor downstream of the tomography section –No profile information Possibility of introducing a transverse deflecting cavity (TDC) to measure additional bunch properties

20. σzσz L deflecting voltage deflector bunch screen z TDC Resolution (1) In absence of quadrupoles resolution increases with distance (L) from TDC to screen

21. σzσz deflecting voltage deflector bunch screen z TDC Resolution (2) In the presence of interspersed quadrupoles this is not so and we must take into account of the entire transfer matrix from TDC to screen – there can be as many quadrupoles as desired

22. Transverse displacement on screen is Beam size on the screen Transfer Matrix to screen gives β d – deflector, β s – screen Want R 12 big → sinΔψ = 1, β s fixed → make β d large Transverse deflecting cavity (1)

23. Transverse deflecting cavity (2) deflecting cavitytomographyEO spectrometer 0.95 1.35 1.6 Δµ x = 90° Δµ y = 65° 1.13

24. Transverse deflecting cavity (3) Reverse of formula gives requirement of cavity voltage Take Δµ = 65° and φ = 0 For streaked bunch to be comparable to un-streaked bunch β x,y = 9 m at the deflecting cavity therefore we need, assuming an emmitance degradation to 10 µm and a bunch length of 4 ps eV 0 ≥ 0.23 MV @ 1.3 GHz Equality gives a streaked beam which is √2 times un-streaked beam –only rough idea of requirements –not enough for ≥ 10 slices (what we would like) → ~ 1 MV ? –longer bunch lengths / better emittance → lower voltage

25. Measurements with TDC Slice emittance & transverse profiles given by –knowledge of R 12 from TDC to screen –one dimension on screen gives slice emittance –other dimension gives bunch length Slice energy spread given by –streaked beam and spectrometer

26. Milestones ALICE shutdown (Cable management installation)25 Oct – 21 Nov 20081 month Diamond drilling of ALICE wall, cable tray installation Off line build of modulesOct 2008 – Jun 20099 months ALICE shutdown1 st Mar – 12 th Apr 2009 6 wks ALICE shutdown8 th Jun – 13 th Jul 20095 wks Installation in Accelerator HallMar – Aug 2009 6 months Test systems in Accelerator HallMay - Oct 20096 months Injection line and ring complete31st Oct 09 Commission with electrons startingNov 2009

27. Conclusions All components of injector line ordered (most already at DL) Order for Extraction / Diagnostic line to go out soon Very Challenging & exciting project ! Good characterisation of the beam at injection & extraction even without TDC Have good location for TDC should it be used in the future –Realistic voltage parameters –Extra beam properties not available with EO –Currently looking at requirements for TDC with RF engineers Aim to be commissioning with electrons at DL in November 2009 Aim to demonstrate that non scaling FFAG technology works and compare results with the theoretical studies performed to gain real experience of operating such accelerators

28. Acknowledgements All the EMMA team –Internal staff –Collaborators