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Muon Production Using a High Power Cyclotron

Muon Production Using a High Power Cyclotron. L. Calabretta, INFN-LNS, Catania on behalf of DAE d ALUS collaboration.

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Muon Production Using a High Power Cyclotron

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  1. Muon Production Using a High Power Cyclotron L. Calabretta, INFN-LNS, Catania on behalf of DAEdALUS collaboration Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  2. DAEdALUS, a Decay-At-rest Experiment for dCP studies At a Laboratory for Underground Science, provides a new approach to search for CP violation in the neutrino sector. The design utilizes high-power proton beam to produce neutrino flux with energy up to 52 MeV from pion and muon decay-at-rest. The experiment searches nm ne for at short baselines corresponding to the atmospheric Dm2 region. The ne is best detected in a large (>100 kton) water Cerenkov detector, preferable Gd-doped , via inverse beta decay. Experiment proposed by J. Conrad (MIT) and M. Shaevitz (Columbia Univ.) Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  3. Lay-out of DAEdALUS experiment. Three proton sources are used to deliver neutrino at a >100 kton water Cerenkov detector placed at 1.5 km underground The duty factor is flexible, but beams must be off for 40% of time to measure background 25% DF 10% DF 25% DF Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  4. Cyclotrons Are a Viable Technology PSI is current world power leader in this energy range ~ 1.3 MW average, 590 MeV protons Higher power face with two major problems: • Capture of more beam current… space-charge at injection • Clean and safe extraction… beam losses <200 W (~10-4) Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  5. Proposed Solution: Acceleration of H2+ ions • Two protons for every ion (1 emA = 2 pmA) • Perveance of 5 emA H2+ at 35 keV/amu is the same as 2 emA of 30 keV protons. Axial injection of 2 emA protons at 30 keV is within state of the art. • The electromagnetic field to dissociate H2+ is higher than for H-, magnetic field as high as 5÷6 Tesla are permitted; • Advantage of extraction by stripping foil: • Clean turn separation at extraction is not necessary; • multiple beams can be extracted simultaneously! Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  6. Main Downtime Causes • electrostatic elements • controls problems • cooling/site power • RF not prominent! Performance 2009 Reliability: 89.5% Beam trips: 25..50 d-1 PSI-HIPA operational data 2009, courtesy of M. Seidel PSI Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  7. The base cyclotron module for DAEDALUS will deliver 10 mA proton beam @ 800 MeV, duty cycle 25%, average power <2 MW> The beam dynamics and the related technical problems for the two accelerators have been investigated: Peak current 5mA of H2+ < 1.25 mA> H2+ 60 MeV/n <150 kW>/600 kW peak Superconducting Coils, Losses due to residual gas Space Charge effects and Electrostatic Deflectors < 1 mA> H2+ 800 MeV/n 25%<2 MW> 8 MW peak Stripping extraction Injector cyclotron, compact & resistive Main cyclotron, separated sectors superconducting Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  8. Extraction lines Multiple beam extractions Stripper foil Stripper foil Stripper foil Last equilibrium orbit RF cavity PSI like Outer diameter 14.5 m 1st equilibrium orbit Double gap cavity, Vmax=250 kV Injection line Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  9. Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  10. Stripper extraction by carbon foil: - 2 MW beam @ 800 MeV crossing a stripper foil 1 mg/cm2 thick release  20 W due to nuclear interaction! - The electrons removed by the strippers have a power of ≈ 550 W Electrons are the main source of stripper damage, but we can remove it! Peak current 20 mA proton, <I>=4 mA H2+ beam If B=0.2 T Re=9 mm Safe limit < 2500 K Stripper foil emerging protons electrons catcher Courtesy I. Okuno, Riken Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  11. Beam losses due to stripping with the residual gases along the acceleration are affordable: H2+, I=2.5 mA, 4 MW  losses <90W <90 W !!! High energy gain/turn is useful to reduce beam losses present simulation <3 MeV/turn> Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  12. RIKEN RSC Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015 Courtesy Iroki Okuno, RIKEN

  13. Control Dewar Side Shield (Open for mainte.) Superconducting Bending Magnet Upper Shield Upper Yoke Side Yoke Lower Yoke SC Main Coil rf-Cavity SC Trim Coil Lower Shield Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  14. RIKEN Sector Magnet - - Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  15. Preliminary study of superconducting magnet and cryostat made by J. Minervini Group, @ MIT-PSFC arXiv.org > physics > arXiv:1209.4886 Sector of DAEdALUS SRC Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  16. Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015 Courtesy F. Meot & Malek Haj Tahar, Brookhaven

  17. Vertical beam envelope Radial beam envelope B2 without gradient B2 with 0.68 kGauss/cm gradient Injection Main Parameters: Large beam emittance at injection (60 AMeV) 37 p mm.mrad (13 times the measured emittance @ ion source). Low magnetic gradient of 0.68 kGauss/cm, only on B2 Courtesy F. Meot & Malek Haj Tahar, Brookhaven Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  18. DAEdALUS Superconducting Ring Cyclotron Space charge effects are negligible during acceleration in the ring cyclotron Vertical beam size along the acceleration in the radial range from 4 to 4.9 m, snapshot at 0° azimuth. The left figure has no charge space effects, 0 mA. The right figure is evaluated with a 5 mA beam H2+ current (10 mA proton) Simulation made by J. Yang and A. Adelman (PSI), using OPAL code Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  19. 0.67 nsec 2.3 mm 4 mm Histogram of 5 mA H2+ beam at the stripper foil position, simulation include space charge effects (OPAL code) Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  20. Request for future Meson Factories • (Cywinski et Al.,doi:10.1016/j.physb.2008.11.203PhysicaB(2009),doi:10.1016/j.physb.2008.11.203) • A pure pulsed mode (ideally at 25kHz, T=40 microsec.), with power >500 kW • An electrostatically tailored pulse mode (e.g. 5 ns, 25kHz), with power >50 kW • A quasi-CW mode, with power > 2 MW • If macro pulse is 4 msec long and 36 msec off (25 kHz), duty cycle is 0.10, Peak current=10 mA  average power 0.8 MW! (ii) The SRC, here presented, deliver a train of 1 nsec width pulses , with a period of 20.3 nsec (49.2 MHz), so selection of single bunch is feasible. 1 pulse in a 20 nsec period with repetition rate of 25 kHz  duty cycle 0.0005, Ipeak=10 mA  4 kW, power limit is due to current limit of H2+ sources. Can be achieved simultaneously at the previous mode on independent lines! (iii) This request can be satisfied quite easily by the described SRC operated in cw with average power up to 5 MW in a single beam line or 4 MW at two beam lines Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  21. The Injector Cyclotron Vmax=55 kV arXiv: 1207.4895 Proposed to drive IsoDAR experiment to search for sterile neutrino at Kamioka • 60 MeV/amu, peak current 5 mA H2+ • Normal conducting coils ~ 4.4 meter coil diameter • Axial injection (spiral inflector) 4 RF Cavities, with Voltage in the range 70-250 kV, 49.2 MHz • 2 Electrostatic Deflectors Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  22. 1 MeV/n 61.7 MeV/n Vertical beam size vs. turns number for different beam current Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  23. Deflector septum 0.5 mm thick Extraction efficiency 99.98%, if beam power is 600 kW on the septum 120 W! Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  24. Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  25. Injection efficiency through the spiral inflector >95% with H2+ current of 7 mA The spiral inflector was tested to operate up to voltage higher than ±13.5 kV • Injection Voltage 60 keV; • H2+ current injected 7 mA; • 4 sen< 1 p mm.mrad; • E.S.Inflector worked at 10 kV. Cyclotron Emittaance meter Steerer Buncher Quads. VIS Solenoid DCCT Solenoid Requested RF voltage 70 kV. achieved < 60 kV! A Test Stand was installed at Best Cyclotron System Laboratory to investigate the injection problems of high intensity H2+ beam Experiment supported also by INFN, CSN5 Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015 Beam Stop Vacuum Pump

  26. A new Ion Source and an injection beam line for H2+, including a RF buncher will be build at MIT to deliver I>40 mA of H2+ Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  27. H2+ current 5 mA Current delivered by the H2+ion source: 50 mA acceptance efficiency 10%, without buncher Serious problem at the injection due to the space charge effect? But for sure we have thermal problem 85% beam lost @ injection 7-12 mA at 2nd post 1.4-2.4 kW @ 200 keV 17-27 mA at 1st post 1.7-2.7 kW @ 100keV With buncher the current requested from the source could be reduced at 30-40 mA 5-8 mA at 3rd post 1.7- 2.8 kW @ 350 keV It is mandatory to replace copper with other materials! Tungsten, tungsten carbide or GLIDCOP? Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015 Liner Dee Liner Dee Back-integrated orbit Dee Beam from SI Liner Dee Liner

  28. Injection into Cyclotron by a RFQ, first proposed by R. Hamm (Jacow, Cycl. Conf. 1981, pag. 359), reduce greatly the beam power lost in central region. Spiral inflector 90° Dipole magnet Ion Source Vacuum pump RFQ Median Plane Focusing lens Vacuum pump Source Cyclotron yoke Ion Source RFQ is able to bunch up to 90% of the injected beam into a bunch length of ≈20° RF. Build a RFQ with working frequency of 49.2 MHZ is feasible. Ion source able to deliver H2+ current up to 10-15 mA are available. Beam current in excess of 8 mA of H2+ could be injected inside the acceptance phase of the cyclotron. The power lost in the central region could be reduced at values < 500 W! Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  29. Summary • H2+ ions can be a key to high-power cyclotrons for many applications • Compactness and relative lower cost of cyclotrons (<130 M€ for the whole system) could be a real option for Future Muon Sources • Exciting times ahead! Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

  30. ...And thats all folks! Thanks for your attention! Workshop on "Future Muon Sources", Huddersfield 12-13 January 2015

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