Three family oscillations The Japanese way: JPARC  SK, HK

1. Future neutrino experiments at accelerators The road-map… and a few itineraries Three family oscillations The Japanese way: JPARC  SK, HK The alpine way: CERN-SPL … and beta-beam and Fréjus Neutrino Factory Superbeam Neutrino Factory and beta-beam R&D EMCOG statements design studies Conclusions

2. Neutrino Oscillations After many years of research (since 1968!) it was established in 1998 that neutrinos change flavor when travelling through space. First observation: solar neutrinos ! (150 000 000 km) Second observation: neutrinos produced in the atmosphere and going through the earth. (13000 km) Recent observation 2003 (exp. K2K, 250 km) accelerator neutrinos Observation of a quantum phenomenon over distances of hundred to millions of km

3. The neutrino mixing matrix: 3 angles and a phase d n3 Dm223= 3 10-3eV2 n2 n1 Dm212= 3 10-5 - 1.5 10-4 eV2 OR? n2 n1 Dm212= 3 10-5 - 1.5 10-4 eV2 Dm223= 3 10-3eV2 n3 q23(atmospheric) = 450 , q12(solar) = 300 , q13(Chooz) < 130 Unknown or poorly known even after approved program: 13 , phase  , sign of Dm13 2

4. neutrino mixing (LMA, natural hierarchy) m2n n3 n2 n1 neis a (quantum) mix of n1(majority, 65%) and n2 (minority 30%) with a small admixture of n3 ( < 13%) (CHOOZ)

5. Oscillation maximum 1.27 Dm2 L / E =p/2 Atmospheric Dm 2= 2.5 10-3 eV 2 L = 500 km @ 1 GeV Solar Dm2 = 7 10-5 eV2 L = 18000km @ 1 GeV Oscillations of 250 MeV neutrinos; Consequences of 3-family oscillations: I There will be nm↔ ne and nt ↔ ne oscillation at L atm P (nm↔ ne)max =~ ½ sin 22 q13+… (small) II There will be CP or T violation CP: P (nm↔ ne) ≠ P (nm↔ ne) T : P (nm↔ ne) ≠ P (ne ↔nm) III we do not know if the neutrino n1 which contains more ne is the lightest one (natural?) or not. P (nm↔ ne)

6. 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 • q12~300Dm122~7 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

7. P(nenm) = ¦A¦2+¦S¦2 + 2 A S sin d P(nenm) = ¦A¦2+¦S¦2 - 2 A S sin d P(nenm) - P(nenm) sind sin (Dm212 L/4E) sin q12 = ACP a sinq13 + solar term… P(nenm) + P(nenm) … need large values of sin q12, Dm212 (LMA) but *not* large sin2q13 … need APPEARANCE … P(nene) is time reversal symmetric (reactors or sun are out) … can be large (30%) for suppressed channel (one small angle vs two large) at wavelength at which ‘solar’ = ‘atmospheric’ and for ne,t … asymmetry is opposite for neandnet

8. ! asymmetry is a few % and requires excellent flux normalization (neutrino fact., beta beam or off axis beam with not-too-near near detector) T asymmetry for sin  = 1 neutrino factory JHFII-HK JHFI-SK NOTE: This is at first maximum! Sensitivity at low values of q13 is better for short baselines, sensitivity at large values of q13 may be better for longer baselines (2d max or 3d max.) This would desserve a more careful analysis! 10 30 0.10 0.30 90

9. LEPTONIC T , CP VIOLATION The baryon asymmetry in the Universe… requires CP or T violation. That of the quarks is not enough! Boris Kayser This leptonic asymmetry would in turn generate baryon asymmetry. (energies typical of the particles that would be exchanged in Baryon decay 1011-15 GeV or so) NB this is CP asymmetry for the Heavy Majorana Neutrinos 1. we don’t know if neutrinos are Majorana particles 2. The CP phases that enter are those of the heavy neutrinos, not the light ones. Nevertheless: leptonic CP violation may be the reason why we exist… lets look for it!

10. Road Map • Experiments to find q13 : • 1. search for nmne in conventional nm beam (MINOS, ICARUS/OPERA) • limitations: NC p0 background, intrinsic ne component in beam • 2. Off-axis beam (JHF-SK, off axis NUMI, off axis CNGS) or • 3. Low Energy Superbeam (BNL  Homestake, SPL Fréjus) Precision experiments to find CP violation -- or to search further if q13 is too small 1. beta-beam 6He++  6Li+++ ne e- and 18Ne 10+  18F 9+ne e+ 2. Neutrino factory with muon storage ring fraction thereof will exist . m+ e+ne nmand m- e-ne nm

11. Roadmap You are here Where do we stand? Where do we go? Which way do we chose? Shortest? Cheapest? Fastest? Taking into account practicalities or politics? You want to go there

12. Where will this get us… X 5 0.10 130 2.50 50 10 Mezzetto comparison of reach in the oscillations; right to left: present limit from the CHOOZ experiment, expected sensitivity from the MINOS experiment, CNGS (OPERA+ICARUS) 0.75 MW JHF to super Kamiokande with an off-axis narrow-band beam, Superbeam: 4 MW CERN-SPL to a 400 kton water Cerenkov in Fréjus (J-PARC phase II similar) from a Neutrino Factory with 40 kton large magnetic detector.

13. Phase II: 4 MW upgrade Phase II HK: 1000 kt JPARC- ~0.6GeV n beam 0.75 MW 50 GeV PS (2008 ) SK: 22.5 kt Kamioka J-PARC K2K~1.2 GeV n beam 0.01 MW 12 GeV PS (1999 2005)

14. T2K (JPARC  Super-Kamiokande) • 295 km baseline • J-PARC approved • neutrino beam and experiment now APPROVED (dec 2003) • Super-Kamiokande: • 22.5 kton fiducial • Excellent e/ ID -- 10-3 • Additional 0/e ID -- 10-2 • (for En~ 500 MeV- 1 GeV) • Matter effects small • need near detector! • European collaboration forming (mailing list: UK(5)-Italy(5)-Saclay-Gva-ETHZ- Spain(2)) This experiment is at the right ratio of Energy to distance Lmax = 300 km at 0.6 GeV

15. J-PARC Facility Super Conducting magnet for n beam line JAERI@Tokai-mura (60km N.E. of KEK) (0.77MW) Construction -->2007/8 Near n detectors @280m and @~2km Budget Request of the n beam line approved (160 OY ~160 M$) 1021POT(130day)≡ “1 year”

16. Off Axis Beam (another NBB option) Far Det. Decay Pipe q Horns Target (ref.: BNL-E889 Proposal) p+ m+ nm WBB w/ intentionally misaligned beam line from det. axis Decay Kinematics • Quasi Monochromatic Beam • x2~3 intense than NBB

17. Expected spectrum Osc. Prob.=sin2(1.27Dm2L/En) Dm2=3x10-3eV2 L=295km nm osc.max. OA1° OA2° OA3° ne contamination 0.21% m-decay K-decay Very small ne/nm @ nm peak ~4500 tot int/22.5kt/yr ~3000 CC int/22.5kt/yr

18. High intensity narrow band beam: Off-axis (OA) beam nm flux from 50 GeV protons (JHF) (ref.: BNL-E889 Proposal) Increase statistics @ osc. max. Decrease bkg from HE tail Tunable by varying beam angle (or: detector position?)

19. ne appearance (continue) sin22qme=0.05 (sin22qme 0.5sin22q13) Dm2 CHOOZ ×20 improvement sin22qme =1/2sin22q13 3×10-3 sin22q13<0.006 (90% C.L.)

20. p p n 0 m 140 m 280 m 2 km 295 km The (J-PARC-n) T2KBeamline Neutrino spectra at diff. dist Problem with water Cerenkov: not very sensitive to details of interactions. Either 280 m or 2 km would be good locations for a very fine grained neutrino detector Planned: a scintillating fiber/water calorimeter. Liquid argon TPC would be a very good (better) candidate! Event numbers: near/SK = m(near[tons]) / 22500 . (300/2)2 = m(near[tons]) => Need 10-50 tons fiducial or so at 2km 200-500 kg fid @ 280m 1.5km 295km 280m

21. Some coments about the off-axis beam The off-axis technique is, really, a way to tune the pion-neutrino beam energy. The fact that the ne component is 0.2-0.3% under the pion neutrino energy peak is true more or less in any wide-band beam. There is a loss of neutrino events wrt on axis wide-band beam due to the fact that the neutrino cross-section is proportional to E. In addition, the beam systematics are very different from those we are used to. In first order the flux is now insensitive to the secondary particles energy but is is now sensitive directly to angular variables in the beam (alignment, pion production angular distribution etc…. A NEW GAME! Finally the oscillation experiment is performed for neutrino energies of 500-800 MeV for which very little is known. (e.g. in GGM, a cut was placed at 1 GeV for neutrino energy) Precise measurement of the properties of these events (and of neutral currents with this visible energy) is crucial for the experiment.

22. Ce que les groupes Européens envisagent de contribuer. décision fin Aout 2004

23. Schematic drawing of Hyper-Kamiokande Super-K 40m 1 Mton (fiducial) volume: Total Length 400m (8 Compartments) Other major goal: improve proton decay reach Supernovae until Andromedes, etc… Excavation will not start until 2011

24. This will be the case in 2011+8+8.3 = 2027.3

25. Motivations to go beyond this… • Intrinsic limits of conventional neutrino beams (intensity, purity, only nm , low energy ) • Go back to Europe and try to establish a CERN-based program on the long run The common source: SPL SPL physics workshop: 25-27 May 2004  CERN SPSC Cogne meeting sept.2004 Superbeam/neutrino Factory design study Neutrino factory The ultimate tool for neutrino oscillations SPL HIPPI Superbeam EURISOL design study APEC design study Very large underground lab Water Cerenkov, Liq.Arg Beta beam EURISOL

26. Possible step 0: Neutrino SUPERBEAM 300 MeV n m Neutrinos small contamination from ne (no K at 2 GeV!) 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 a window of opportunity for digging the cavern stating in 2008 (safety tunnel in Frejus) Agreement has been signed between IN2P3/CEA/INFN to study this

27. Europe: SPLFrejus CERN Geneve • SPL @ CERN • 2.2GeV, 50Hz, 2.3x1014p/pulse • 4MW Now under R&D phase 130km 40kt 400kt Italy

28. CERN: b-beam baseline scenario Nuclear Physics SPL Decay ring Brho = 1500 Tm B = 5 T Lss = 2500 m SPS Decay Ring ISOL target & Ion source ECR Cyclotrons, linac or FFAG Rapid cycling synchrotron PS

29. Tunnels and Magnets • Civil engineering costs: Estimate of 400 MCHF for 1.3% incline (13.9 mrad) • Ringlenth: 6850 m, Radius=300 m, Straight sections=2500 m • Magnet cost: First estimate at 100 MCHF FLUKA simulated losses in surrounding rock (no public health implications)

30. Detectors Liquid Ar TPC (~100kton) UNO (400kton Water Cherenkov)

31. Combination of beta beam with low energy super beam Unique to CERN: need few 100 GeV accelerator (PS + SPS will do!) experience in radioactive beams at ISOLDE many unknowns: what is the duty factor that can be achieved? (needs < 10-3 ) combines CP and T violation tests e m (+) (T) m e (p+) (CP) e m (-) (T) m e (p-) Can this work???? theoretical studies now on beta beam + SPL target and horn R&D  design study together with EURISOL

32. DUTY FACTOR (this is an issue for low energy superbeam and beta beam) • Sub-GeV Atmospheric Neutrino interactions are at rate ~100/kt/year. • ~ 50% ne and 50% nm • For a 500 kton detector this will give 50 000 events of the wrong lepton • At this energy the directionality if poor (cuts will not be effective) • It is necesary to discriminate with timing! • Duty factor required < 10-3 • SPL (50 Hz), needs 20 microseconds every 20 ms. (accumulator) • Betabeam : needs stacking of ions along the perimeter of the SR. (2 bunches of 10ns / 7km) (more bunches of same intensity OK)

33. L. Mosca

34. -- Neutrino Factory --CERN layout 1016p/s 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+

35. Where do you prefer to take shifts?

36. Neutrino fluxesm+ -> e+nenm nm/n e ratio reversed by switching m+/ m- ne nm spectra are different No high energy tail. Very well known flux (10-3) -- E&sE calibration from muon spin precession -- angular divergence: small effect if q < 0.2/g, - - absolute flux measured from muon current or by nm e--> m-ne in near expt. -- in triangle ring, muon polarization precesses and averages out (preferred, -> calib of energy, energy spread) Similar comments apply to beta beam, except spin 0  Energy and energy spread have to be obtained from the properties of the storage ring (Trajectories, RF volts and frequency, etc…) m polarization controls ne flux: m+ -X> nein forward direction

37. Iron calorimeter Magnetized Charge discrimination B = 1 T R = 10 m, L = 20 m Fiducial mass = 40 kT Detector Also: L Arg detector: magnetized ICARUS Wrong sign muons, electrons, taus and NC evts *-> Events for 1 year nmsignal (sin2q13=0.01) nm CC ne CC Baseline 732 Km 1.1 x 105 (J-PARC I SK = 40) 3.5 x 107 5.9 x 107 1.0 x 105 3500 Km 2.4 x 106 1.2 x 106

38. 6 classes of events right sign muon nm -> nm -> m+ electron/positron nm -> ne-> e+ or ne-> ne-> e- wrong sign muon ne-> nm -> m- right sign tau nm -> nt -> t+-> m+ nn wrong sign tau ne -> nt -> t--> m- nn no lepton NC & other taus

39. ICARUS NB: additional potential wrt magnetized iron calorimeter: tau detection, sign of *low* energy electrons, if magnetized. May redefine the optimal parameters of neutrino factory

40. CP asymmetries compare ne to ne probabilities m is prop matter density, positive for neutrinos, negative for antineutrinos HUGE effect for distance around 6000 km!! Resonance around 12 GeV when = 0

41. 5-10 GeV 10-20 GeV 20-30 GeV 30-40 GeV 40-50 GeV CP violation (ctd) • Matter effect must be subtracted. One believes this can be done with uncertainty • Of order 2%. Also spectrum of matter effect and CP violation is different • It is important to subtract in bins of measured energy. • knowledge of spectrum is essential here! 40 kton L M D 50 GeV nufact 5 yrs 1021m /yr In fact, 20-30 GeV Is enough! Best distance is 2500-3500 km e.g. Fermilab or BNL -> west coast or …

42. Silver A. Donini et al channel at neutrino factory High energy neutrinos at NuFact allow observation of net (wrong sign muons with missing energy and P). UNIQUE Liquid Argon or OPERA-like detector at 3000 km. Since the sind dependence has opposite sign with the wrong sign muons, this solves ambiguities that will invariably appear if only wrong sign muons are used. ambiguities with only wrong sign muons (3500 km) associating taus to muons (no efficencies, but only OPERA mass) studies on-going equal event number curves muon vstaus

43. NUFACT Superbeam only Beta-beam only Betabeam + superbeam Upgrade 400kton-> 1 Mton J-PARC HK 540 kton?

44. The proposed Roadmap M. Vretenar • Consistently with the recent DG talk on the future of CERN, is in preparation a document (“Future Projects and Associated R&D”) to be presented at the December Council. • The chapter “Upgrade of the Proton Injector Complex” presents a roadmap, consistent with 2 basic assumptions: • construction of Linac4 2007/10 (before end of LHC payment) • construction of SPL in 2008/15 (after end of LHC payments) Linac 4 approval SPL approval LHC upgrade

45. L. Mosca This fits very well!

46. Some Critical issues Super beam & Neutrino Factory SPL cost, cleanliness, power limits capability to handle different time structures Accumulation of protons Target and target station Collection (Horn at high radiation and high rep rate) Design/optimization of multihorn system and decay tunel Muon Cooling of large emittance muon beam (MICE + kickers) Fast and cheap accceleration (RF source, FFAG, kickers) Beta beam Ion yields Activation Stacking Do we need a new PS? Megaton detector What size cavity can be dug? cost/time scale Photosensitive devices!!! Other detector (Larg, other) safety….

47. Motivations to go beyond this… • Intrinsic limits of conventional neutrino beams (intensity, purity, only nm , low energy ) • Go back to Europe and try to establish a CERN-based program on the long run The common source: SPL SPL physics workshop: May 2004  CERN SPC Cogne meeting sept.2004 Superbeam/neutrino Factory design study Neutrino factory The ultimate tool for neutrino oscillations SPL HIPPI Superbeam EURISOL design study APEC design study Very large underground lab Water Cerenkov, L.Arg Beta beam EURISOL

48. EMCOG (European Muon Concertation and Oversight Group) • FIRST SET OF BASIC GOALS • The long-term goal is to have a Conceptual Design Report for a European Neutrino Factory Complex by the time of JHF & LHC start-up, so that, by that date, this would be a valid option for the future of CERN. • An earlier construction for the proton driver (SPL + accumulator & compressor rings) is conceivable and, of course, highly desirable. • The SPL and targetry and horn R&D have therefore to be given the highest priority. • Cooling is on the critical path for the neutrino factory itself; there is a consensus that a cooling experiment is a necessity. • The emphasis should be the definition of • practical experimental projects with a duration of 2-5 years. • Such projects can be seen in the following four areas:

49. Superbeam & Beta Beam cost estimates E

50. Neutrino Factory studies and R&D USA, Europe, Japan have each their scheme. Only one has been costed, US study II: + detector: MINOS * 10 = about 300 M€ or M$ Neutrino Factory CAN be done…..but it is too expensive as is. Aim: ascertain challenges can be met + cut cost in half.