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Challenges of future accelerator-based Neutrino Facilities

Challenges of future accelerator-based Neutrino Facilities. Introduction Proton drivers T arget and Collection Neutrino Factory challenges muon cooling acceleration (FFAGs) B eta- B eam challenges See NUFACT04 site:

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Challenges of future accelerator-based Neutrino Facilities

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  1. Challenges of future accelerator-based Neutrino Facilities Introduction Proton drivers Target and Collection Neutrino Factory challenges muon cooling acceleration (FFAGs) Beta-Beam challenges See NUFACT04 site: http://www-kuno.phys.sci.osaka-u.ac.jp/~enufact04/ http://muonstoragerings.cern.ch

  2. Where are we? • We know that there are three families of active, light neutrinos (LEP) • Solar neutrino oscillations are established(Homestake+Gallium+Kam+SK+SNO+KamLAND) • Atmospheric (nm -> ) oscillations are established (IMB+Kam+SK+Macro+Sudan+K2K) • At that frequency, electron neutrino oscillations are small (CHOOZ) • This allows a consistent picture with 3-family oscillations • q12~300Dm122~8.5 10-5eV2 q23~450Dm232~ 2.5 10-3eV2q13 <~ 100 • with several unknown parameters q13, d, mass hierarchy leptonic CP & T violations => an exciting experimental program for at least 25 years *) Where do we go? *)to set the scale: CP violation in quarks was discovered in 1964 and there is still an important program (K0pi0, B-factories, Neutron EDM, LHCb, BTeV….) to go on for >>10 years…i.e. a total of >50 yrs. and we have not discovered leptonic CP yet! 5. LSND ? ( miniBooNe) This result is not consistent with three families of neutrinos oscillating, and is not supported (nor is it completely contradicted) by other experiments. If confirmed, this would be even more exciting See Barger et al PRD 63 033002

  3. Atmospheric “wavelenght”

  4. Road Map • A Experiments to find q13 : • search fornmne • --in conventional nm beam (MINOS, ICARUS/OPERA) • limitations: NC p0 background, intrinsic ne component in beam • -- in reactor experiments • --Off-axis beam (JHF-SK, off axis NUMI, off axis CNGS) or • --Low Energy Superbeam (BNL  Homestake, SPL Fréjus) B Precision experiments to find CP violation -- or to search further if q13 is too small -- beta-beamand -- Neutrino factory with muon decay storage ring and fraction thereof will exist .

  5. As always in neutrino physics the event rate is a major concern Most future facilities are based on a High Intensity Proton source. Example: a series of facilities envisaged for CERN

  6. CERN-SPL-based Neutrino SUPERBEAM 300 MeV n m Neutrinos small contamination from ne (no K at 2 GeV!) target! Fréjus underground lab. A large underground water Cerenkov (400 kton) UNO/HyperK or/and a large L.Arg detector. also : proton decay search, supernovae events solar and atmospheric neutrinos. Performance similar to J-PARC II There is awindow of opportunityfor digging the cavern stating in 2008 (safety tunnel in Frejus)

  7. -- Neutrino Factory -- CERN layout -- cooling! 1016p/s target! acceleration! 1.2 1014 m/s =1.2 1021 m/yr _ 0.9 1021 m/yr m+ e+ne nm 3 1020 ne/yr 3 1020 nm/yr oscillates ne nm interacts givingm- WRONG SIGN MUON interacts giving m+

  8. CERN: b-beam baseline scenario Nuclear Physics EU pride.. SPL target! Decay ring B = 5 T Lss = 2500 m SPS Decay Ring ISOL target & Ion source ECR Cyclotrons, linac or FFAG Stacking! Rapid cycling synchrotron PS Same detectors as Superbeam !

  9. The reference facility: J-PARC0.75 MW at start, evolving Nuclear and Particle Experimental Facility Materials and Life Science Experimental Facility Nuclear Transmutation Neutrino to Kamiokande 3 GeV Synchrotron (25 Hz, 1MW) 50 GeV Synchrotron (0.75 MW) Linac (350m) J-PARC = Japan Proton Accelerator Research Complex

  10. Fermilab Proton Driver8 GeV Superconducting Linac Basic concept inspired by the observation (by Bill Foster) that $/GeV for SCRF has fallen dramatically  Consider a solution in which H- beam is accelerated to 8 GeV in a superconducting linac and injected directly into the Main Injector Attractions of a superconducting linac: Many components exist (few parts to design vs. new synchrotron) Copy SNS, RIA, & AccSys Linac up to 1.2 GeV “TESLA” Cryo modules from 1.2  8 GeV Smaller emittance than a synchrotron High beam power simultaneously at 8 & 120 GeV Plus, high beam power (2 MW) over entire 40-120 GeV range Flexibility for the future Issues Uncontrolled H- stripping Halo formation and control Cost

  11. Fermilab Proton Driver8 GeV SC Linac: Other possible missions (from the mind of Bill Foster) Neutrino “Super- Beams” SY-120 Fixed-Target Damping Rings for TESLA @ FNAL With 8 GeV e+ Preacc. NUMI Off- Axis X-RAY FEL LAB 8 GeV neutrino 8 GeV Linac ~ 700m Active Length 1% LC Systems Test Main Injector @2 MW Bunching Ring Target and Muon Cooling Channel Recirculating Linac for Neutrino Factory Long-Pulse Spallation Source & Neutrino Target Short Baseline Detector Array VLHC at Fermilab Neutrinos to “Homestake” Anti- Proton

  12. High intensity proton accelerators pose many challenges but certainly one of the most critical one is the Target ! Typical Dimensions: L  30 cm, R  1 cm •  4 MW of protons (i.e. 40 000 light bulbs!) • into a big cigar…. it would immediately go to smoke.

  13. Liquid Mercury Target R&D Experiment @BNL and @CERN Speed of Hg disruption Max v 20 m/smeasured v// 3 m/s (design calls for 20m/s) 1 cm Protons liquid jet of mercury jet remains intact for more than 20 microseconds.

  14. Liquid Mercury Target R&D US scheme: jet is inside a very high field tapered solenoid (20 T max) this was tested at the Laboratoire de Champs Intenses (Grenoble) A. Fabich et al– CERN-BNL-Grenoble

  15. Targetry: other ideas Many difficulties: enormous power density  lifetime problems Stationary granular target: Replace target between bunches: rotating solid target Proposed rotating tantalum target ring Densham Sievers

  16. Target & collection The CERN magnetic horn for pion collection Current of 300 kA Prototype built at CERN p Protons 2.2 GeV 4 MW B = 0 B1/R Major issue is resistance of horn material to combination of shock, Joule heating & irradiation

  17. Target & collection Proposal to test a 10m/s Hg Jet in a 15T Solenoid with an Intense Proton Beam • Participating Institutions • RAL • CERN • KEK • BNL • ORNL • Princeton University aim: Installation and commissioning at CERN by April 2006

  18. Hg-jet system Power absorbed in Hg-jet 1 MW Operating pressure 100 Bar Flow rate 2 t/m Jet speed 30 m/s Jet diameter 10 mm Temperature- Inlet to target 30° C- Exit from target 100° C Total Hg inventory 10 t Pump power 50 kW

  19. Muon ionization cooling Frictional cooling is only for m+ A novel method for m+ andm- is needed: ionization cooling principle reality (simplified) reduce pt and pl with as little heating as possible: Hydrogen! increase pl fast acceleration Never realized in practice ! A realistic prototype should be built and proven to be adequate to the Neutrino Factory requirements.

  20. MICE setup: cooling + diagnostics

  21. Operation of RF cavities at high gradient in magnetic field Dark current backgrounds measured on a 805 MHz cavity in magnetic field! with a 1mm scintillating fiber at d=O(1m) This will be also a source of backgrounds for MICE:

  22. RF cavity (800 MHz) at Fermilab being pushed to its limits (35 MV/m) to study dark current emission in magnetic field. Sees clear enhancement due to B field. Various diagnostics methods photographic paper, scintillating fibers Microscope ------ BCT and solid state counters have demonstrated this and allowed precise measurements Real cavities will be equipped with Be windows which do not show sign of being pitted contrary to Cu

  23. MICE cooling channel R&D The challenge: Thin windows + safety regulations RF module (Berkeley, Los Alamos, CERN, RAL) LH2 window (IIT, NIU, ICAR) First cavity Be window to minimize thickness

  24. MICE installation phases m - STEP I 2006 STEP II STEP III 2007 STEP IV STEP V 2008 STEP VI

  25. Muon acceleration Previous accelerator scheme: LINAC + Recirculating Linear Accelerator (RLA) Very costly and rigid use. Proposed solution: Fixed Field Alternating Gradient (FFAG). a new type of accelerator with B-field shaped as rk -->particles can be kept and accelerated over a range of energies of ~factor 3. Japan Scheme New US Scheme

  26. Muon acceleration: FFAG Much progress in Japan with the development and demonstration of large acceptance FFAG accelerators Latest ideas in US have lead to the invention of a new type of FFAG (“non-scaling FFAG”) interesting for more than just Neutrino Factories (e.g. from SPL to 20 GeV?) require a demonstration experiment (PRISM, electron prototype) • Perhaps US & Japanese concepts are merging to produce something better ??

  27. $$$$$ … COST … $$$$$ USA, Europe, Japan have each their scheme for Nu-Fact. Only one has been costed, US 'study II' and estimated (2001) ~2B$. The aim of the R&D is also to understand if solutions could reduce cost in half. + detector: MINOS * 10 = about 300 M€ or M$ Neutrino Factory CAN be done…..but it is too expensive as is. Aim of R&D: ascertain challenges can be met + cut cost in half.

  28. We are working towards a “World Design Study” with an emphasis on cost reduction. $$$$$ … COST … $$$$$ 28 Why we are optimistic: In the previous design ~ ¾ of the cost came from these 3 equally expensive sub-systems.New design has similar performance to Study 2 performance and keeps both m+ and m- ! (RF phase rotation) NUFACT 2004: cost can be reduced by at least 1/3 = proton driver + 1 B € MAYBE the Neutrino Factory is not so far in the future after all…. S. Geer:

  29. Beta beam Challenges 1. Intense production of ions, in particular + emitters (18Ne) 2. Clean acceleration: life time is much longer than muons but the decays produce activation in the rings) 3. Stacking in the storage ring

  30. 6He production by 9Be(n,a) Converter technology: (J. Nolen, NPA 701 (2002) 312c) Layout very similar to planned EURISOL converter target aiming for 1015 fissions per s.

  31. Production of b+ emitters Spallation of close-by target nuclides:18,19Ne from MgO and 34,35Ar in CaO Production rate for 18Ne is 1x1012 s-1(with 2.2 GeV 100 mA proton beam, cross-sections of some mb and a 1 m long oxide target of 10% theoretical density) 19Ne can be produced with one order of magnitude higher intensity but the half life is 17 seconds! A PULSED souce could be realized by ECR (P.Sortais Moriond 2003)

  32. From dc ions to very short bunches 2 x 1.1 ms to decay ring (4 bunches with few ns) B SPS t 2.2 ms 2.2 ms SPS: injection of 8 (16) bunches from PS. Acceleration to decay ring energy and ejection of 4 + 4 bunches. Repetition time 8 s. PS: 1s flat bottom with 8 (16) injections. Acceleration in ~1s to top PS energy B B 1 s 1 s PS PS t t RCS: further bunching to ~100 ns Acceleration to ~300 MeV/u. 8 (16) repetitions over 1s. Post accelerator linac: acceleration to ~100 MeV/u. 8 (16) repetitions over 1s. 60 GHz ECR: accumulation for 1/8 (1/16) s ejection of fully stripped ~20ms pulse. 16 batches during 1s. t t Target: dc production during 1 s. 1 s 1 s 7 s

  33. STACKING is necessary to ensure duty cycle less than 10-3 inject off energy (using e.g. dispersive section)

  34. Summary The construction of future neutrino facilities poses many stimulating challenges Enthusiastic R&D is ongoing, and a lot has already been accomplished (despite all the difficulties related to lack of funding) -- much more is needed! Many of these facilities offer other a large range of physics interests ranging from nuclear physics to rare muon decay and neutrinos -- AND… LHC upgrade… The long term goal, LEPTONIC CP VIOLATION, makes the effort highly worthwhile

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