1. Bruno Muratori STFC, Daresbury Laboratory Commissioning EMMA 02/07/09 PRISM workshop – Imperial College

2. Motivation / Introduction Give an overview of what has been thought about – given talks & previous attempts (Scott, Eberhard, Shane, Carol, François, Dejan and others) Does not mean it is always correct or complete – this is part of our duty in the next months May be different & much better ways of implementing procedures – these are initial thoughts Requires several iterations & discussions Process started & lots to think about Aim to be ready by end of summer (~ October) Need help – who is available & for what ?

3. Overview Commissioning –Preparing machine for beam set-up DAQ & controls & hardware set-up diagnostic devices required –Getting beam into the machine & where you want it –Making sure all desired properties are achieved for the bunch (full characterisation etc.) for the machine (e.g. dispersion-free sections) –Making all the desired measurements –Set-up machine for particular experiments –Requires several fully consistent simulations of the machine !

4. ALICE schematic Need similar schematic for EMMA injection line, ring and extraction line (shall be enormously more detailed … !)

5. Injection Line (1) ALICE EMMA ALICE quadrupoles SRS quadrupoles New quadrupoles Faraday Cup Screen last dispersive section dogleg tomography

6. Injection line (2)

7. Injection Line (3)

8. Injection Line Commissioning (1) Prepare ALICE as Injector for EMMA –Bunch length: ~ 10 ps rms in order to decrease space charge effects and for painting the longitudinal phase space –Energy spread: < 100 keV in order to have a better defined beam for painting and avoid chromaticity –Bunch charge: 15 – 30 pC in order to reduce collective effects (e.g space charge) –Normalised transverse emittance: 5 - 10 µm in order to decrease space charge effects but still have a well defined beam for painting

9. Injection Line Commissioning (2) –Beam energy: 10 to 20 MeV with the ability to be changed several times a day. –Beam characterisation (full 6D) Bunch length / Charge / Emittance / Energy / Energy spread –Hardware commissioning –Controls & online model commissioning Which is best suited ? –DAS commissioning

10. Injection Line Commissioning (3) Probable sequence of ALICE set up to act as an injector for EMMA –Set the ALICE injector up for an appropriate booster beam energy (6 – 8 MeV) at 1 – 2 bunch charges (15 – 30 pC) too low / too high ? –Characterise the beam in the ALICE injector for energy spread, emittance and bunch length etc. –Set 3-4 injection energies in the range 10 to 20 MeV and set the rest of ALICE for injection into the EMMA ring –Measure the beam characteristics at each combination of energy and bunch charge

11. Detailed Procedures (1) Dogleg & dispersion –Iterative procedure setting two external quads – then central – then repeat Matching to tomography –Not trivial & very sensitive even in initial tracking models Last dispersive section and setting D x & D ’ x –Tomography helps keep the beam small –Dedicated model with some quads off –Measure dispersion in two places → derivative known –Turn quads to nominal model value → D x & D ’ x should be close to desired value... is this a valid procedure ?

12. Measurements in Injection Line (1) Emittance –Tomography section –Quadrupole scan Bunch length –Zero cross method with 2 nd linac cavity used as a buncher and YAG screen in dogleg Charge –Faraday cup after dipole or tomography Energy & Energy spread –Slit & YAG in last dispersive section

13. Commissioning the EMMA ring (1) Injection Septum 65° Kicker Cavities x 19 Extraction Septum 70° Kicker Screen Wire Scanner Wall Current Monitor Wire Scanner Scree n BPM x 82 D Quadrupole x 42 F Quadrupole x 42 16 Vertical Correctors IOT Racks (3) Waveguide distribution Kicker Power Suppli es Septum Power Supply Septum Power Supply Kicker Power Suppli es

14. Commissioning the EMMA ring (2) Injection

15. Commissioning the EMMA ring (3) Extraction

16. Commissioning the EMMA ring (4) Extraction

17. Before Injection into EMMA –Start with easier energy (probably 17-18 MeV) –Start with a low charge ? (e.g. 1 pC) –Measure injection energy to within 100 keV –Set nominal septum & kicker values Inject beam & look at first few BPMs – no acceleration –Calibrate this w.r.t. chosen model (ZGOUBI) –Make half a turn & extract & diagnose beam (may be better to circulate first & measure tunes & TOF ?) –Measure bunch properties in extraction line Commissioning the EMMA ring (5)

18. Establishing the orbit (1) Look at Beam Position Monitor (BPM) one by one from the injection point (not symmetric → not straightforward) Adjust initial beam position (x,x’,y,y’) as well as Quad current and position BPM

19. Establishing the orbit (2) Double focusing lattice (QF and QD) Bend fields are created by shifting quadrupoles QF QD Linear slide 4 knobs –QF and QD strength –QF and QD position (horizontally) 4 parameters to fit –Q x and Q y –TOF shape and offset Should have model to predict 4 parameters according to desired lattice which model is best ?

20. Measurements in EMMA ring Measurement of time of flight –Change frequency until no synchrotron oscillations –Frequency then translates into TOF –Hence find minimum of TOF Relationship of TOF to lattice parameters / tune –Tune vs. energy Study variation of all parameters to lattice properties Interpretation of BPM readings –Not all identical & only symmetry every other cell –Important to model all BPM readings → GPT / other Best code to do this – ZGOUBI (more this p.m.)

21. ALICE EMMA SRS quadrupoles New quadrupoles TD Cavity spectrometer dipole tomography, EO and spectrometer matching section and TDC first dispersive section Diagnostic line (1)

22. Diagnostic line (2)

23. Diagnostic line (3) deflecting cavitytomographyEO spectrometer

24. Extraction Line Commissioning (1) Much harder than injection as no precise knowledge of energy Set kickers & septum at ‘best guess’ Extract ideal – pencil-like beam Measure energy with screen & dipole Iterate Zero the dispersion on exit of 1 st straight (not obvious) ‘Match’ to tomography – not trivial & again possibility for collaboration (already two students & me but...) Make bunch measurements

25. How to achieve zero dispersion at the exit of straight ? –Usually done by centering the beam and then slightly changing the energy & ensuring spot is motionless –Where do we introduce this change ? main linac → changes dynamics of EMMA & spot could appear still with dispersion non-zero switch off one of the EMMA cavities ? → also changes the dynamics slightly reduce all of them ? look at centroid trajectories ? Detailed Procedures (2)

26. Measurements in Extraction Line (1) Emittance –Tomography section Slice emittance –TDC & screen in tomography section Bunch length –EO monitor and / or TDC Charge –Faraday cup after spectrometer dipole Energy spread –Slit & YAG in first dispersive section / spec. dipole Slice energy spread –TDC & spectrometer dipole

27. Modelling (1) Model ALICE injector to deliver EMMA beam (10 ps etc.) Create model of ALICE to EMMA injector line in GPT –Run this model both on & off line for comparisons / predictions Create S2E model for all of EMMA in GPT –Run with field maps & misalignments for comparisons / predictions –Run all the way to spectrometer & dump in the EMMA extraction line Compare this with ZGOUBI models & FFEMMAG / other models wherever possible

28. Aperture survey Phase space at injection Scan aperture in phase space with a pencil beam Use steerers vertically & kickers horizontally When is normalized acceptance is 3 mm rad ? Explore acceptance at all energies Should also be modelled with FFEMMAG, GPT & others To be done at all energies from 10 to 20 MeV x’ x pencil beam

29. Online Modelling (1) Ring optics – what things may look like courtesy S. Machida

30. Online Modelling (2) Injection orbit and optics - what things may look like Set septum and kicker strength See orbit and optics of incoming beam courtesy S. Machida

31. We Need Your Help Identify all tasks required to operate EMMA successfully - started Identify & describe procedures – started –TOF / Tunes / Orbit correction / Experiments / other ? Help prepare programme of work - started Help develop online models where required - started Help interpret data & measurements correctly – what does everything mean ? Begin to lay out a commissioning plan - started Estimate resources available to the project and in particular commissioning – started I will send list of tasks & initial commissioning thoughts

32. Update commissioning document to have –Project plan for EMMA commissioning preparation Deliverables / Milestones Who can look into it, STFC, collaborators etc. Simulations to be carried out (Richard D’Arcy & others) Procedure writing Give this plan to collaborators for feedback & help Full Commissioning Plan by end of October Major tasks e.g. - Build online model with interface (ZGOUBI / PI-ZGOUBI) –Already under way thanks to Yoel Giboudot, David Kelliher, Shinji, Machida, Kiril Marinov, Ben Shepher We Need Your Help

33. Thanks you for your attention Still lots of work to be done ! Expect requests for help soon... Pre-Commissioning Workshop ~mid November Everyone invited