Future accelerator scenarios

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Some future accelerator scenarios at RAL.

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Future accelerator scenarios

  1. 1. FELIX QVI POTVIT RERVM COGNOSCERE CAVSAS Some future accelerator scenarios at RAL David Findlay Accelerator Division ISIS Department Rutherford Appleton Laboratory
  2. 2. <ul><li>ISIS accelerator upgrades: </li></ul><ul><ul><li>½ MW upgrade </li></ul></ul><ul><ul><li>1 MW upgrade </li></ul></ul><ul><ul><li>2 ½ MW upgrade </li></ul></ul><ul><ul><li>5 MW upgrade </li></ul></ul><ul><li>Other accelerator projects: </li></ul><ul><ul><li>Neutrino factory </li></ul></ul><ul><ul><li>[MICE] </li></ul></ul><ul><li>RF considerations </li></ul>
  3. 3. <ul><li>People involved: </li></ul><ul><ul><li>Dean Adams </li></ul></ul><ul><ul><li>Mike Clarke-Gayther </li></ul></ul><ul><ul><li>Paul Drumm </li></ul></ul><ul><ul><li>Ian Gardner </li></ul></ul><ul><ul><li>Frank Gerigk </li></ul></ul><ul><ul><li>Chris Prior </li></ul></ul><ul><ul><li>Grahame Rees </li></ul></ul><ul><ul><li>Kevin Tilley </li></ul></ul><ul><ul><li>Chris Warsop </li></ul></ul><ul><ul><li>… </li></ul></ul>
  4. 4. ISIS upgrades not necessarily accelerator upgrades
  5. 5. Source strength × Reliability × Instrumentation × Innovation × Investment × Support facilities × Support staff × Cost effectiveness × User community 10 × 1 × 1 × 1 × 1 × 1 × 1 × 1 × 1 2 × 1 × 1.26 × 1.26 × 1.26 × 1.26 × 1.26 × 1.26 × 1.26 1 × 1 × 1.39 × 1.39 × 1.39 × 1.39 × 1.39 × 1.39 × 1.39
  6. 6. <ul><li>Source strength </li></ul><ul><ul><li>Actually neutrons per electron-volt per steradian per second </li></ul></ul><ul><ul><li>— not protons (although powers usually in terms of protons) </li></ul></ul>Reflector Moderators Primary target Protons Moderator
  7. 7. <ul><li>Accelerator beam power: </li></ul><ul><ul><li>Beam energy (electron-volts) × beam current (amps) = beam power (watts) </li></ul></ul><ul><ul><li>Or ( MeV × µA ) ÷ 1000 = kW </li></ul></ul><ul><li>ISIS at present: 800 MeV, 200 µA  160 kW ~2×10 16 primary neutrons per second </li></ul><ul><li>ISIS after RFQ and second harmonic RF upgrades: 800 MeV, 300 µA  240 kW ( ¼ MW) ~3×10 16 primary neutrons per second </li></ul>
  8. 8. ISIS at present
  9. 9. Second Target Station upgrade No power upgrade, but 18 more instruments (7 on Day 1)
  10. 10. ISIS at present
  11. 11. New ~180 MeV linac ½ MW upgrade — extra power by increasing current Present 70 MeV linac
  12. 15. Higher injection energy  space charge forces less of a problem Should be able to inject and accelerate higher currents ~300 µA at 70 MeV (with 2RF upgrade) ~600 µA at 180 MeV? 800 MeV × 600 µA = 480 kW ≈ 0.5 MW Need detailed beam dynamics calculations to confirm — ASTeC Intense Beams Group
  13. 16. Proton beam Individual proton in beam Space charge forces
  14. 17. <ul><li>What physical modifications to ring necessary? </li></ul><ul><ul><li>Increased fields in injection dipoles (~65%) (70 MeV  369 MeV/c, 180 MeV  608 MeV/c) </li></ul></ul><ul><ul><li>Increased activation from trapping losses — increased incomplete stripping losses — but opportunity for beam chopper </li></ul></ul><ul><ul><li>Decreased adiabatic damping — beam may be harder to extract — new extract septum? </li></ul></ul><ul><ul><li>More power from RF cavity drivers (I a : 10  13 A) </li></ul></ul><ul><ul><li>Target? </li></ul></ul>
  15. 19. Beam loss Why chopper? Ion source Linac Ring Bunching Also to minimise RF transients and control beam intensity
  16. 20. No beam loss Ion source Linac Ring Bunching With chopper — gaps in beam
  17. 21. Chopper performance required DC accelerator RF accelerator ns – µs spacing ESS: 280 MHz, bunch spacing 3.57 ns Switch between bunches Partially chopped bunches a problem! Tune shifts! Good Bad On Off
  18. 22. <ul><li>RAL beam chopper design </li></ul><ul><ul><li>Robust design with explicit provision for high power beam collection </li></ul></ul><ul><ul><li>Switching time: between 280 MHz beam bunches </li></ul></ul>Slow transmission line Lumped line — thermally hardened 0 1 0 1 2 ns 8 ns Up to 100 µs
  19. 23. Close-coupled chopper module 1145 mm Slow switch Fast switch Beam Buncher cavity Buncher cavity
  20. 24. 1 MW upgrade Extra power by increasing energy
  21. 25. Transmutation and energy production with high power accelerators, G. P. Lawrence, Los Alamos National Laboratory, http://epaper.kek.jp/p95/ARTICLES/FPD/FPD03.PDF Proton range in tungsten target from integrating stopping power
  22. 27. 1 MW upgrade 800 MeV synch. TS1 TS2 3 GeV synch. TS3 (+ 8 GeV) µ
  23. 28. Circumference of 3 GeV synchrotron = 3 × circumference of 800 MeV synchrotron 800 MeV 26 m radius 2 – 3 µC per bunch 3 GeV 78 m radius Can “fit in” three times as much charge
  24. 29. <ul><li>800 MeV, 300 µA  240 kW </li></ul><ul><li>3 GeV, 300 µA  900 kW </li></ul><ul><ul><li>— ~4 × beam power, so 4 × RF power </li></ul></ul><ul><li>Use same RF drivers as on present ISIS synchrotron  ~30 RF cavities  ~30 RF drivers (HPDs) </li></ul>
  25. 31. <ul><li>Synchrotrons are swept frequency devices (resonant frequency of RF accelerating cavities has to change throughout acceleration cycle) </li></ul><ul><li>Linacs are fixed frequency devices </li></ul><ul><li>On ISIS </li></ul><ul><ul><li>linac, 202.5 MHz </li></ul></ul><ul><ul><li>synchrotron, 1.3 - 3.1 MHz </li></ul></ul><ul><ul><li>1 MW synchrotron, 3.1 - 3.6 MHz </li></ul></ul>
  26. 36. <ul><li>Synergy with neutrino factory </li></ul><ul><ul><li>Same synchrotron </li></ul></ul><ul><ul><ul><li>if design magnets to go up to 8 GeV </li></ul></ul></ul><ul><ul><ul><li>if run at (say) 50/3 pps to avoid more RF power </li></ul></ul></ul><ul><ul><li>could be used for neutrino factory ( e.g. target tests) </li></ul></ul>
  27. 37. 2½ & 5 MW upgrades
  28. 38. 2½ and/or 5 MW upgrades
  29. 39. 2½ MW upgrade TS3 µ 180 MeV linac 2 × 1.2 GeV synchrotrons 39 m radius 1 × 3 GeV synchrotron 78 m radius 50 pps
  30. 40. Circumference of 3 GeV synchrotron = 2 × circumference of 1.2 GeV synchrotron 3 GeV 78 m radius 1.2 GeV 39 m radius 1.2 GeV 39 m radius
  31. 41. 5 MW upgrade TS3 µ 180 MeV linac 2 × 1.2 GeV synchrotrons 39 m radius 2 × 6 GeV synchrotron 78 m radius 2 × 25 pps
  32. 42. <ul><li>Neutrino factory </li></ul><ul><ul><li>To produce ~10 21 neutrinos per year </li></ul></ul><ul><ul><li>To facilitate measurements of mass of neutrino through long base line experiments </li></ul></ul><ul><ul><ul><li>Neutrino physics: very hot topic; neutrinos not mass-less; neutrino masses are “something new”; physics “beyond the standard model”; implications for cosmology; possibly helps explains matter/antimatter asymmetry of the universe; why is there a physical universe at all </li></ul></ul></ul><ul><ul><li>Running ~2020? </li></ul></ul><ul><ul><li>Only one likely in world, but not yet one design </li></ul></ul>
  33. 43. Want intense beam of neutrinos — but can’t accelerate neutrinos (no charge) Can get neutrinos from muons If muons decay in flight, neutrinos tend to go in direction of muons   So get intense beams of neutrinos by accelerating intense beam of muons — but no natural source of muons
  34. 44. p + A Z  n,  , … (pion production)    +  (pion  muon + neutrino)   e +  +  (muon  electron + 2 × neutrinos) <ul><li>Particle masses and lifetimes </li></ul><ul><ul><li>neutrino ~0 </li></ul></ul><ul><ul><li>electron 0.5 MeV stable </li></ul></ul><ul><ul><li>muon 106 MeV 2.2 µs </li></ul></ul><ul><ul><li>pion 140 MeV 26 ns </li></ul></ul><ul><ul><li>proton 938 MeV stable </li></ul></ul><ul><ul><li>neutron 940 MeV 15 mins. </li></ul></ul>
  35. 45. <ul><li>Key elements of neutrino factory </li></ul><ul><ul><li>Few MW protons </li></ul></ul><ul><ul><li>Target to produce pions and let them out </li></ul></ul><ul><ul><li>Decay & capture channel where pions decay to muons </li></ul></ul><ul><ul><li>Muon cooling </li></ul></ul><ul><ul><li>Muon acceleration (~100 kW muons) </li></ul></ul><ul><ul><li>Muon storage ring where muons decay into neutrinos </li></ul></ul><ul><ul><li>[Detectors several 1000 miles away looking at storage ring] </li></ul></ul>
  36. 46. p + A Z  n,  , … (pion production)    +  (pion  muon + neutrino)   e +  +  (muon  electron + 2 × neutrinos) KARMEN experiment at ISIS Electron anti-neutrinos not produced by ISIS, so their appearance would be evidence for neutrino oscillations and thus evidence for neutrino mass  ’ s in all directions — KARMEN close to target
  37. 47. Muon Storage Ring High current H – source Cooling Muon Acceleration ‘ near’ detector (1000–3000km) ‘ far’ detector (5000–8000km) ‘ local’ detector Proton Driver Target Capture
  38. 48. UK Neutrino Factory
  39. 50. FNAL BNL CERN GSI CEA INFN JHF DUBNA RAL? Neutrino experiment
  40. 51. <ul><li>Neutrino factory: proton driver options </li></ul><ul><ul><li>2.2 GeV SC linac (CERN) 15 GeV synchrotron (RAL) 8 & 16 GeV synchrotron (FNAL) 15 GeV synchrotron (CERN) 24 GeV synchrotron (BNL) 50 GeV synchrotron (JHF) </li></ul></ul><ul><li>Typically 4 MW of protons required </li></ul>
  41. 52. Protons  pions  muons http://puhep1.princeton.edu/mumu/target/targettrans15.pdf
  42. 53. Muons produced with large energy and angular spreads — pretty ghastly source for an accelerator “ Phase rotation” in energy-time phase space to selectively speed up slow muons — several different schemes, all need RF “ Cooling” to reduce transverse motion but not longitudinal motion — reduce longitud. and transv. energy in absorber — put back longitud. only — MICE experiment at RAL
  43. 54. Particle with transverse momentum After losing energy in absorber After acceleration in RF cavity Muon Ionisation Cooling Experiment
  44. 55. <ul><li>Muon acceleration </li></ul><ul><ul><li>Muon mass 106 MeV, mean life 2 µs — must be quick! </li></ul></ul><ul><ul><li>Synchrotrons not possible — must use linacs Recirculating linacs to minimise cost </li></ul></ul><ul><ul><li>Superconducting linacs to minimise overall length by maximising acceleration gradient </li></ul></ul><ul><ul><li>Few microamps of muons cf. ~1 mA in proton driver — ~100 kW beam power </li></ul></ul><ul><ul><li>Muon beam emittances large “Large&quot; aperture linacs “Low” frequencies, e.g. ~200 MHz </li></ul></ul>
  45. 56. 50 GeV muon recirculating superconducting linac ISIS synchrotron
  46. 57. <ul><li>RF engineering considerations </li></ul><ul><ul><li>Valves & klystrons </li></ul></ul><ul><ul><li>Transmission lines </li></ul></ul><ul><ul><li>Acceleration cavities </li></ul></ul><ul><ul><li>Amplitude & phase control </li></ul></ul><ul><ul><li>Beam compensation </li></ul></ul><ul><ul><li>— and people </li></ul></ul>
  47. 58. <ul><li>Valves & klystrons </li></ul><ul><ul><li>~100 in proton driver, ~100 in muon accelerator </li></ul></ul><ul><ul><li>20000 h lifetime, 4 h to change  4% time lost </li></ul></ul><ul><ul><li>Test stands to test on receipt (valves for ISIS linac not always acceptable) </li></ul></ul><ul><ul><li>Cosset in operation ( e.g. closed loop heater power control) </li></ul></ul>
  48. 59. <ul><li>Transmission lines and acceleration cavities </li></ul><ul><ul><li>Arc protection ( e.g. for klystrons) </li></ul></ul><ul><ul><li>Quality of engineering in highly radioactive areas ( e.g. muon phase rotation) </li></ul></ul><ul><ul><li>Design for remote manipulation? </li></ul></ul><ul><ul><li>“ Bussed” RF over ~500 m Waveguide, ~10 kW, –40 dB couplers Temperature stability important 5°C, 500 m, 500 MHz, 10 –5 coeff. therm. expans.  15° phase shift </li></ul></ul>
  49. 60. <ul><li>Amplitude and phase control </li></ul><ul><ul><li>Usual requirements: control good to 1% and 1° </li></ul></ul><ul><ul><li>Superconducting pulsed cavities — more difficult control problem than with normal conducting since greater fraction of RF power goes to beam </li></ul></ul><ul><ul><li>Expect to benefit from SNS experience </li></ul></ul><ul><li>Beam compensation </li></ul><ul><ul><li>In synchrotron, beam pulse induces signal in resonant RF cavity — have to “subtract” off — feed-forward systems </li></ul></ul><ul><ul><li>“ Cathode follower” driver — low impedance — RAL/KEK/ANL collaboration </li></ul></ul>
  50. 61. <ul><li>Servo loops for RF for ISIS proton synchrotron </li></ul><ul><ul><li>VFO matched to time-varying magnetic field — 0.17 – 0.71 tesla in 10 ms — 1.3 – 3.1 MHz </li></ul></ul><ul><ul><li>Loops to control amplitude of cavity voltages </li></ul></ul><ul><ul><li>Loops to control phases of cavities around ring </li></ul></ul><ul><ul><li>Loops to hold each cavity on tune </li></ul></ul><ul><ul><li>Loops to vary RF frequency to hold beam on orbit </li></ul></ul><ul><li>Same for upgrade synchrotrons </li></ul>
  51. 62. <ul><li>People </li></ul><ul><ul><li>Accelerator RF work both routine and highly scientific/technical at same time </li></ul></ul><ul><ul><li>Need to draw young people in — recognised within CCLRC-PPARC’s initiative for university accelerator centres </li></ul></ul><ul><ul><li>But need hardware to train people on — important element of current bid to set up proton driver front end test stand at RAL — CCLRC – university (Imperial College) collaboration </li></ul></ul>
  52. 64. <ul><li>Summary </li></ul><ul><ul><li>Described some ISIS accelerator upgrades </li></ul></ul><ul><ul><li>Described other accelerator possibilities at RAL </li></ul></ul><ul><ul><li>Likelihood of these projects difficult to quantify, but we did get the £100M Second Target Station </li></ul></ul>

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