The ISIS Facility

1. The ISIS Facility John Thomason Synchrotron Group Leader ISIS Department Rutherford Appleton Laboratory / STFC (With thanks to David Findlay) Fermilab, 13 January 2012

2. ISIS Rutherford Appleton Laboratory, Oxfordshire

3. ISIS • World’s most productive spallation neutron source(if no longer highest pulsed beam power) • Flagship STFC facility [Science & Technology Facilities Council] • Driven by UK’s high-power proton accelerators • UK has largest national neutron user community of any country • Accelerator physics necessary for continuing operational development- and also for enabling entire programmes on materials R&D • Need to plan for upgrades

4. ISIS science • World-leading centre for research in the physical and life sciences • Neutron and muon instruments for properties of materials in terms of molecular structure • National and international community of >2000 scientists • Research fields include clean energy, the environment, pharmaceuticals and health care, nanotechnology, materials engineering and IT • ~450 publications/year (~9000 total over 26 years) • MICE (Muon Ionisation Cooling Experiment)

5. ISIS • Fundamental purpose - to investigate structure and dynamics of molecular matter • Complements light sources (Diamond) • Neutrons: ~0.1 eV → ~1Å Structure Paracetamol Atomic motions

6. Impact of ISIS science e c s h d n

7. ISIS organisation • Accelerator Division - accelerator operations + R&D • Design Division - engineering, accelerators + neutron instruments • Experimental Operations Division - target operations, sample and environment • Instrumentation Division - neutron counters, data acquisition • Science Diffraction Division - crystallography, disordered materials, large-scale structures • Spectroscopy and Support Division - excitations, molecular spectroscopy, muons

9. RFQ: 665 keV H–, 4-rod, 202 MHz Linac: 70 MeV H–, 25 mA, 202 MHz, 200 µs, 50 pps Synchrotron: 800 MeV proton, 50 Hz 5 µC each acceleration cycle Dual harmonic RF system Targets: 2 × W (Ta coated) Protons: 2 × ~100 ns pulses, ~300 ns apart Moderators: TS-1: 2 × H2O, 1 × liq. CH4, 1 × liq. H2 TS-2: 1 × liq. H2 / solid CH4, 1 × solid CH4 Instruments: TS-1: 20 TS-2: 7 (+ 4 more now funded) ~340 staff

10. –35 kV H– ion source

11. 665 keV 4-rod 202 MHz RFQ

12. 70 MeV 202 MHz 4-tank H– linac

13. 1.3 – 3.1 & 2.6 – 6.2 MHz 70 – 800 MeV proton synchrotron

14. Superperiods 9, 0 and 1 of 800 MeV synchrotron

15. Protons to TS-2 Protons to TS-1 EPB1 and EPB2 to TS-1 and TS-2 above synchrotron

16. ISIS TS-1 experimental hall, 20 instruments

17. ISIS TS-2 experimental hall, 7 instruments + 4 under way

18. TS-1 tungsten target, plates

19. TS-2 tungsten target, solid cylinder

20. Typically 180 days a year running for users • Maintenance/shutdown • ~1 – 2 weeks machine physics + run-up • ~40 day cycle • ~3 day machine physics • ~250 days a year machine running overall • Obsolescence mitigation programme • ~10% of annual budget • e.g. synchrotron main magnet power supply ~5/year

21. 1998 – 2002 2003 – 2007 2007 – 2011

23. ISIS accelerator operations depend on accelerator R&D • Need skilled, knowledgeable and experienced staff to maintain ISIS operations sustainably – for example • Greater beam powers for two target stations • Hands-on maintenance – regulatory issues • Accommodating MICE • Need to enable accelerator staff to engage with similar staff elsewhere • Need to look forward to possible ISIS upgrades

24. ISIS – Accelerator R&D • Front End Test Stand • To demonstrate key technologies for front ends of next generation of high-power pulsed proton accelerators • Only dedicated high power proton accelerator hardware R&D in UK • Ring R&D • Theory cf. measurement, benchmarking, … • Exploits rare opportunities for accelerator physics measurements on high-current ring • ISIS upgrades • To build on current success of ISIS

25. Beam diagnostics and beam dump MEBT and beam chopper Laser profile measurement 324 MHz, 3 MeV, 4-vane RFQ 3-solenoid magnetic LEBT 65 keV, 60 mA, 2 ms, 50 Hz, H– ion source Front End Test Stand Alan Letchford’s talk earlier Ion source collaborations:CSNS, CERN, Culham, Oxford

26. ISIS MW Upgrade Scenarios My talk later 1) Replace 70 MeV ISIS linac by new ~180 MeV linac (~0.5 MW) 2) ~3.3 GeV RCS fed by bucket-to-bucket transfer from ISIS 800 MeV synchrotron (1MW, perhaps more) 3) Charge-exchange injection from 800 MeV linac (2 – 5 MW)

27. Studies of coherent resonances • ISIS ring nominal tunes Qx, Qy = 4.31, 3.83 • Tune decreases as current increases — avoid 2Qy = 7 ! Storage ring mode Predicted onset of resonance

28. Simulations and measurements of beam bunches Simulations at 0.0 ms (end of injection) and 0.5 ms (peak trapping loss) cf. measurement Simulation (black) Measurement (orange) Understanding and optimising dual harmonic performance will be key to increasing ISIS operational intensity 1RF 0.0 ms 0.5 ms DHRF

29. ISIS beam loss simulations using ORBIT Beam loss Time (ms) ORBIT simulations, 600k particles,64 CPUs, 3-D space charge Simulated beam loss: 9 % Measured beam Loss: 8 %

30. Key areas of accelerator expertise at ISIS Essentially: science and technology of proton accelerators with benefit of operational experience Optimal application of electrical, electronic, mechanical, RF and vacuum engineering Ability to calculate beam dynamics in detail– including benchmarking codes in standard andnon-standard states (e.g. coasting beams) Design and operation of beam diagnostics devices and interpretation of the signals arising from the devices

31. Key areas of accelerator expertise – continued Appreciation of the practical problems posed by high-power beam stops and collimators, induction of radioactivity in machine structures, etc.– including high-power targets State-of-the-art code development and hardware architecture for running the codes Assessment of the implications for ISIS of facilitating other R&D programmes such as MICE

32. Overall aims – Accelerators Run ISIS sustainably Prepare for ISIS upgrades Act as centre/host for proton accelerator R&D in UK Collaborate nationally and internationally