Challenges of future acceleratorbased Neutrino Facilities Introduction Proton

Challenges of future accelerator-based Neutrino Facilities Introduction Proton drivers Target and Collection Neutrino Factory challenges muon cooling acceleration (FFAGs) Beta-Beam challenges See NUFACT 04 site: http: //www-kuno. phys. sci. osaka-u. ac. jp/~enufact 04/ http: //muonstoragerings. cern. ch Rencontres du Viet-Nam 2004 Alain Blondel

Where are we? 1. 2. 3. 4. We know that there are three families of active, light neutrinos (LEP) Solar neutrino oscillations are established (Homestake+Gallium+Kam+SK+SNO+Kam. LAND) Atmospheric (nm -> ) oscillations are established (IMB+Kam+SK+Macro+Sudan+K 2 K) At that frequency, electron neutrino oscillations are small (CHOOZ) This allows a consistent picture with 3 -family oscillations q 12 ~300 Dm 122~8. 5 10 -5 e. V 2 q 23 ~450 Dm 23 2~ 2. 5 10 -3 e. V 2 with several unknown parameters q 13, d, mass hierarchy Where do we go? q 13 <~ 100 leptonic CP & T violations => an exciting experimental program for at least 25 years *) *)to set the scale: CP violation in quarks was discovered in 1964 and there is still an important program (K 0 pi 0, B-factories, Neutron EDM, LHCb, BTe. V…. ) to go on for >>10 years…i. e. a total of >50 yrs. and we have not discovered leptonic CP yet! 5. LSND ? ( mini. Boo. Ne) 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 Rencontres du Viet-Nam 2004 Alain Blondel

Atmospheric “wavelenght” Rencontres du Viet-Nam 2004 Alain Blondel

Road Map A Experiments to find q 13 : search for nm ne --in conventional nm beam (MINOS, ICARUS/OPERA) limitations: NC p 0 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 q 13 is too small -- beta-beam -- and Neutrino factory with muon decay storage ring and fraction thereof will exist. Rencontres du Viet-Nam 2004 Alain Blondel

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 Rencontres du Viet-Nam 2004 Alain Blondel

CERN-SPL-based Neutrino SUPERBEAM 300 Me. V n m Neutrinos small contamination from ne (no K at 2 Ge. V!) target! Fréjus underground lab. A large underground water Cerenkov (400 kton) UNO/Hyper. K 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 a window of opportunity for digging the cavern stating in 2008 (safety tunnel in Frejus) Rencontres du Viet-Nam 2004 Alain Blondel

-- Neutrino Factory -- CERN layout -- cooling! 1016 p/s target! acceleration! 1. 2 1014 m/s =1. 2 1021 m/yr 0. 9 1021 m/yr 3 1020 ne/yr 3 1020 nm/yr m+ e + n e _ nm oscillates ne nm interacts giving m- WRONG SIGN MUON interacts giving m+ Rencontres du Viet-Nam 2004 Alain Blondel

CERN: -beam baseline scenario EU pride. . Nuclear Physics SPL target! Decay ring B=5 T Decay ISOL target & Ion source SPS ECR Cyclotrons, linac or FFAG Rapid cycling synchrotron Ring Lss = 2500 m Stacking! PS Same detectors as Superbeam ! Rencontres du Viet-Nam 2004 Alain Blondel

The reference facility: J-PARC 0. 75 MW at start, evolving Materials and Life Science Experimental Facility Nuclear and Particle Experimental Facility Nuclear Transmutation Neutrino to Kamiokande Linac (350 m) 3 Ge. V Synchrotron (25 Hz, 1 MW) 50 Ge. V Synchrotron (0. 75 MW) J-PARC = Japan Proton Accelerator Research Complex Rencontres du Viet-Nam 2004 Alain Blondel

Fermilab Proton Driver 8 Ge. V Superconducting Linac Basic concept inspired by the observation (by Bill Foster) that $/Ge. V for SCRF has fallen dramatically Consider a solution in which H- beam is accelerated to 8 Ge. V 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, & Acc. Sys Linac up to 1. 2 Ge. V “TESLA” Cryo modules from 1. 2 8 Ge. V Smaller emittance than a synchrotron High beam power simultaneously at 8 & 120 Ge. V Plus, high beam power (2 MW) over entire 40 -120 Ge. V range Flexibility for the future Issues Uncontrolled H- stripping Halo formation and control Cost Rencontres du Viet-Nam 2004 Alain Blondel

Fermilab Proton Driver 8 Ge. V SC Linac: Other possible missions (from the mind of Bill Foster) Neutrino “Super. Beams” NUMI Off. Axis 8 Ge. V Anti. Proton SY-120 Fixed. Target Damping Rings for TESLA @ FNAL With 8 Ge. V e+ Preacc. X-RAY FEL LAB 8 Ge. V Linac neutrino ~ 700 m Active Length 1% LC Systems Test Main Injector @2 MW Short Baseline Detector Array Neutrinos to “Homestake” Bunching Ring Target and Muon Cooling Channel Long-Pulse Spallation Source & Neutrino Target Recirculating Linac for Neutrino Factory VLHC at Fermilab Rencontres du Viet-Nam 2004 Alain Blondel

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. Rencontres du Viet-Nam 2004 Alain Blondel

Liquid Mercury Target R&D Experiment @BNL and @CERN Speed of Hg disruption Max v 20 m/s measured v// 3 m/s (design calls for 20 m/s) rc ury e fm uid liq o jet 1 cm s on t o r P jet remains intact for more than 20 microseconds. Rencontres du Viet-Nam 2004 Alain Blondel

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 Rencontres du Viet-Nam 2004 Alain Blondel

Targetry: other ideas Many difficulties: enormous power density lifetime problems Replace target between bunches: Stationary granular target: rotating solid target Proposed rotating tantalum target ring Densham Sievers Rencontres du Viet-Nam 2004 Alain Blondel

Target & collection The CERN magnetic horn for pion collection Current of 300 k. A Prototype built at CERN p Protons 2. 2 Ge. V 4 MW B=0 B 1/R Major issue is resistance of horn material to combination of shock, Joule heating & irradiation Rencontres du Viet-Nam 2004 Alain Blondel

Target & collection Proposal to test a 10 m/s Hg Jet in a 15 T Solenoid with an Intense Proton Beam Participating Institutions 1) RAL 2) CERN 3) KEK 4) BNL 5) ORNL 6) Princeton University aim: Installation and commissioning at CERN by April 2006 Rencontres du Viet-Nam 2004 Alain Blondel

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 k. W Rencontres du Viet-Nam 2004 Alain Blondel

Muon ionization cooling Frictional cooling is only for m+ A novel method for m+ and m- is needed: ionization principle cooling 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. Rencontres du Viet-Nam 2004 Alain Blondel

MICE setup: cooling + diagnostics Rencontres du Viet-Nam 2004 Alain Blondel

Operation of RF cavities at high gradient in magnetic field Dark current backgrounds measured on a 805 MHz cavity in magnetic field! with a 1 mm scintillating fiber at d=O(1 m) This will be also a source of backgrounds for MICE: Rencontres du Viet-Nam 2004 Alain Blondel

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 Rencontres du Viet-Nam 2004 Alain Blondel

MICE cooling channel R&D The challenge: Thin windows + safety regulations LH 2 window (IIT, NIU, ICAR) RF module (Berkeley, Los Alamos, CERN, RAL) First cavity Be window to minimize thickness. Rencontres du Viet-Nam 2004 Alain Blondel

MICE installation phases m - 2006 STEP III 2007 STEP IV STEP V 2008 STEP VI Rencontres du Viet-Nam 2004 Alain Blondel

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 Bfield shaped as rk -->particles can be kept and accelerated over a range of energies of ~factor 3. Japan Scheme New US Scheme Rencontres du Viet-Nam 2004 Alain Blondel

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 Ge. V? ) require a demonstration experiment (PRISM, electron prototype) è Perhaps US & Japanese concepts are merging to produce something better ? ? Rencontres du Viet-Nam 2004 Alain Blondel

$$$$$ … COST … $$$$$ USA, Europe, Japan have each their scheme for Nu-Fact. Only one has been costed, US 'study II' and estimated (2001) ~2 B$. The aim of the R&D is also to understand if solutions could reduce cost in half. + detector: MINOS * 10 = about 300 M€ or M$ Neutrino Factory CAN be done…. . but it is too expensive as is. Rencontres du Viet-Nam 2004 Alain Blondel Aim of R&D: ascertain challenges can be met + cut cost in half.

$$$$$ … COST … $$$$$ 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: We are working towards a “World Design Study” with an emphasis on cost reduction.

Beta beam Challenges 1. Intense production of ions, in particular + emitters (18 Ne) 2. Clean acceleration: life time is much longer than muons but the decays produce activation in the rings) 3. Stacking in the storage ring Rencontres du Viet-Nam 2004 Alain Blondel

6 He production by 9 Be(n, a) Converter technology: (J. Nolen, NPA 701 (2002) 312 c) Layout very similar to planned EURISOL converter target aiming for 1015 fissions per s. Rencontres du Viet-Nam 2004 Alain Blondel

Production of b+ emitters Spallation of close-by target nuclides: 18, 19 Ne from Mg. O and 34, 35 Ar in Ca. O Production rate for 18 Ne is 1 x 1012 s-1 (with 2. 2 Ge. V 100 m. A proton beam, crosssections of some mb and a 1 m long oxide target of 10% theoretical density) 19 Ne 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) Rencontres du Viet-Nam 2004 Alain Blondel

From dc ions to very short bunches 2 x 1. 1 ms to decay ring (4 bunches with few ns) B SPS 2. 2 ms B 1 s PS 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: 1 s flat bottom with 8 (16) injections. Acceleration in ~1 s to top PS energy t B 1 s PS t t RCS: further bunching to ~100 ns Acceleration to ~300 Me. V/u. 8 (16) repetitions over 1 s. Post accelerator linac: acceleration to ~100 Me. V/u. 8 (16) repetitions over 1 s. t 1 s 60 GHz ECR: accumulation for 1/8 (1/16) s ejection of fully stripped ~20 ms pulse. 16 batches during 1 s. Target: dc production during 1 s. 7 s t 1 s Rencontres du Viet-Nam 2004 Alain Blondel

STACKING is necessary to ensure duty cycle less than 10 -3 inject off energy (using e. g. dispersive section) Rencontres du Viet-Nam 2004 Alain Blondel

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 Rencontres du Viet-Nam 2004 Alain Blondel