1. EMMA Overview Ben Shepherd Magnetics and Radiation Sources Group ASTeC STFC Daresbury Laboratory

2. 2/31Ben Shepherd – EMMA Status21 June 2010 Outline Introduction to EMMA – the world’s first non-scaling FFAG History of FFAGs Motivations Technical challenges Current status and next steps

3. 3/31Ben Shepherd – EMMA Status21 June 2010 Project Overview Electron Model for Many Applications (EMMA) Will be the world’s first non-scaling FFAG Part of a larger project called CONFORM ( COnstruction of a Nonscaling FFag for Oncology, Research, and Medicine ) www.conform.ac.uk/ www.conform.ac.uk/ Project started on 2 nd April 2007 and it has a 3.5 year timescale CONFORM is the 1 st project of the BASROC consortium www.basroc.org.uk/ 3 work packages to the project: EMMA design and construction of a non scaling FFAG - £5.75m PAMELA design study - £865k Applications study - £273k

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13. 13/31Ben Shepherd – EMMA Status21 June 2010 Example: retune lattice to vary longitudinal Time of Flight curve, range and minimum Aims & Objectives Example: retune lattice to vary resonances crossed during acceleration An EMMA objective: to understand the NS- FFAG beam dynamics as function of lattice tuning and RF parameters Tune plane (per cell) Time of Flight vs Energy Graphs courtesy of Scott Berg, BNL

14. 14/31Ben Shepherd – EMMA Status21 June 2010 EMMA Layout & Basic Parameters Energy range10 – 20 MeV LatticeF/D Doublet Circumference16.6m No of cells42 Normalised transverse acceptance 3 π mm-mrad Frequency (nominal) 1.3 GHz No of RF cavities19 Average beam current 13 μA Repetition rate1, 5, 10, 20 Hz Bunch charge16-32 pC single bunch

15. 15/31Ben Shepherd – EMMA Status21 June 2010 DC Magnets Offset quadrupoles provide independent dipole and quadrupole fields Challenges: High aspect ratio (“all ends and no middle”) Wide aperture (+ lateral movement) Proximity to each other and other devices All magnets must be identical (to 0.1%)

16. 16/31Ben Shepherd – EMMA Status21 June 2010 DC Magnets Detailed pole profile design  extend good gradient region over required aperture Clamp plates added to outside of doublet  reduce stray fields, enable precise adjustment of integrated gradient Detailed 3D modelling and field maps produced  assess effect of field overlap (determined by inscribed radius) (determined by symmetry)

17. 17/31Ben Shepherd – EMMA Status21 June 2010 Fast Magnets for Injection Space is very limited! Kicker Septum 65° Injection

18. 18/31Ben Shepherd – EMMA Status21 June 2010 Septum Parameters Max. beam deflection (injection) 65° Max. beam deflection (extraction) 70° Max. flux density in the gap0.83 T Excitation pulse (half-sine-wave)25 µS Peak excitation voltage2 kV Peak excitation current9 kA Repetition rate 20 Hz Circulating beam Laminations Gap Conductor Septum

19. 19/31Ben Shepherd – EMMA Status21 June 2010 Septum Measurement Techniques d=6mm Long coil (integrated field) Long curved coil (field integrated along the trajectory) Field map measurement  Septum magnet field reached B=1T (125%) (<0.8T needed).  Max. stray field strength ~4x10 -4 [Tm] (at 0.7 T gap field)  Detailed field map B(x, y, z=0, t) available.  We need to estimate the impact of a stray field of that magnitude on the circulating beam.

20. 20/31Ben Shepherd – EMMA Status21 June 2010 Summary of Septum Measurements  Septum magnet field reached B=1T (125%) (<0.8T needed).  Max. stray field strength ~4x10 -4 [Tm] (at 0.7 T gap field)  Detailed field map B(x, y, z=0, t) available.  We need to estimate the impact of a stray field of that magnitude on the circulating beam. Shielding added to reduce stray field 35 μs half-sine- wave pulse

21. 21/31Ben Shepherd – EMMA Status21 June 2010 Kicker Parameters Max. beam deflection 105 mrad Hor. good field region46 mm Min vertical gap25 mm Hor. deflection quality± 1 % Min. flat top (+0 -1%)  5 nS Field rise/fall time < 50 nS Repetition rate20 Hz Physical length available100 mm Field strength 0.007 Tm Peak voltage30 kV Peak current1.3kA

22. 22/31Ben Shepherd – EMMA Status21 June 2010 Kicker Measurement Method  Rectangular coil, 300 mm long, 3mm thick; metallic layer (100 μm) on the appropriate sides.  Coil positioning with the Hall-probe bench.  Gives the integrated field strength.  Plans to make a detailed field map with a 6 mm diameter small coil didn’t quite work out: stray capacitance in the coil creates a resonance.

23. 23/31Ben Shepherd – EMMA Status21 June 2010 Kicker Measurement Results  Full kicker strength 0.007 Tm reached at 28 kV.  Ringing in the pulse tail does not seem to be as bad as the CT signal suggests.  Pulse fall-time ~70 ns (longer than the specified 50 ns).  In-situ field probes installed on all the kickers, tested and calibrated  Fine-tuning the injection kicker pulse shape by adjusting various circuit elements (a.k.a. knobs). resistors varistors (voltage-dependent resistors) bias current

24. 24/31Ben Shepherd – EMMA Status21 June 2010 RF Cavities E B welding Machining Normal conducting single cell design Frequency: 1.3GHz ± 5.6MHz Voltage: 20-120kV Power required: 3.6kW / cavity Manufacture and delivery of 20 production cavities (inc one spare) completed by Niowave High quality manufacture including electron beam welding of body to reduce distortion Chemical etching adopted to improve Q (Qo 18,500 to 20,400) Cavities exceed EMMA specification Input Coupler Times Microwave

25. 25/31Ben Shepherd – EMMA Status21 June 2010 Electron Beam Position Monitors The BPM electronics system has to deliver 50 m resolution over a large aperture for a single bunch of electrons on a turn-by- turn basis. Locally mounted coupler card amplifies and separates signals from opposite buttons in time, to give a 12nS delay between each. Signals combined and transmitted via a single high quality coax cable to…. ……VME based detector cards located in rack room outside of shielded area. Status:- All elements of the detector and digitisation stages are designed. Contract has been placed to design the VME interface. Production Coupler RF Detector, Clock, Control & ADC

26. 26/31Ben Shepherd – EMMA Status21 June 2010 Online Modelling An online model runs in the background in the control room, defining a virtual accelerator EPICS interface; we operate the VA in the same way as the real EMMA Allows high-level software to be tested offline (another VA instance local to your PC) Machine settings can be transferred between the VA and the real EMMA High-level software Beam threading, tune measurement, ToF,... High-level software Beam threading, tune measurement, ToF,... EPICS IOCs EPICS IOC Real EMMA Magnets, BPMs, RF, vacuum, PSS... Real EMMA Magnets, BPMs, RF, vacuum, PSS... Virtual EMMA ZGOUBI model: magnets, RF, BPMs Virtual EMMA ZGOUBI model: magnets, RF, BPMs EPICS Channel Access layer

27. 27/31Ben Shepherd – EMMA Status21 June 2010 Example of high-level software GUI panel

28. 28/31Ben Shepherd – EMMA Status21 June 2010 Current Build Status Final module (M35 – extraction) was installed on 16 June 2010 EMMA 4-sector commissioning began on 20 June Full ring commissioning scheduled for August Latest results in ALICE eLog: http://alice.stfc.ac.uk/elog/alicelog/ http://alice.stfc.ac.uk/elog/alicelog/

29. 29/31Ben Shepherd – EMMA Status21 June 2010 Injection line commissioning A 15 MeV beam was successfully transported down the EMMA injection line in March 2010 Since then, the first section has been successfully used as a single-bunch energy spectrometer for ALICE YAG-1 YAG-2 YAG-3 YAG-4 YAG-5 YAG-6

30. 30/31Ben Shepherd – EMMA Status21 June 2010 CONFORM Project Open Day Church House, London, 24 th June http://www.hep.manchester.ac.uk/g/accelerators/conform/openday2010/ http://www.hep.manchester.ac.uk/g/accelerators/conform/openday2010/ Report progress on the project including EMMA PAMELA Design Study Cell Studies Accelerator Driven Subcritical Reactors Opportunities for Industry Next steps EMMA PAMELA ADSR

31. 31/31Ben Shepherd – EMMA Status21 June 2010 Conclusions EMMA will be an excellent machine to study the properties of non-scaling FFAG lattices Designing and building this machine to spec has been challenging DC magnets – wide aperture Pulsed magnets – high field, short pulse BPMs – single bunch, high accuracy Full ring commissioning will take place in August 2010 Thanks to everyone whose slides I’ve stolen for this talk Mike Craddock (TRIUMF), Neil Bliss, Kiril Marinov,...