EMMA Design and Construction

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

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 All matches achieved to good accuracy – wyaiwyg ‘what you ask is what you get’ Different match for all energies (10-20 MeV) Twiss parameters and dispersion and its derivative are different for every energy and have to be precise

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

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

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

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

10. 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 Injection and Extraction (2)

11. EMMA Kicker Magnet Fast Switching 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. 133 mm internal 100 mm 180 mm internal 25° Injection and Extraction • 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 Final Parameters

13. Septum Concept Electrical feedthroughs (conductor path to power supply requires to be short to reduce inductance) Translation & rotation in-vacuum bearings 0 - 7° Motorised linear actuators external to vacuum -7 to 15 mm Vacuum flange Aluminium wire seal 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.

14. 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 Septum Design Section view of septum in vacuum chamber ISO view of septum with vacuum chamber removed Plan view of septum in vacuum chamber

15. Cavity Design 110 mm Cavity machined form 3 pieces and EB welded at 2 locations Input coupling loop Coolant channels Aperture Ø 40 mm Probe EVAC Flange Capacitive post tuner Normal conducting single cell re-entrant cavity design optimised for high shunt impedance

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

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

18. deflecting cavity tomography EO spectrometer Diagnostic line

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

21. deflecting voltage z σz screen deflector bunch 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 deflecting cavity (1) • Transfer Matrix to screen gives • Transverse displacement on screen is βd – deflector, βs – screen • Want R12 big → sinΔψ = 1, βs fixed → make βd large • Beam size on the screen

23. deflecting cavity tomography EO spectrometer 1.6 1.35 1.13 0.95 Δµy = 65° Δµx = 90° Transverse deflecting cavity (2)

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 • βx,y = 9 m at the deflecting cavity therefore we need, assuming an emmitance degradation to 10 µm and a bunch length of 4 ps eV0 ≥ 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 R12 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 2008 1 month Diamond drilling of ALICE wall, cable tray installation Off line build of modules Oct 2008 – Jun 2009 9 months ALICE shutdown 1st Mar – 12th Apr 2009 6 wks ALICE shutdown 8th Jun – 13th Jul 2009 5 wks Installation in Accelerator Hall Mar – Aug 2009 6 months Test systems in Accelerator Hall May - Oct 2009 6 months Injection line and ring complete 31st Oct 09 Commission with electrons starting Nov 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