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Future Accelerator Based Neutrino Experiments

Aug.22,2011 Lomonosov Conf Moscow. Future Accelerator Based Neutrino Experiments. Takashi Kobayashi Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK). n e. n m. n t. Standard picture of 3 flavor mixing. Flavor eigenstates.

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Future Accelerator Based Neutrino Experiments

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  1. Aug.22,2011 Lomonosov Conf Moscow Future Accelerator Based Neutrino Experiments Takashi Kobayashi Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK)

  2. ne nm nt Standard picture of 3 flavor mixing Flavor eigenstates Mass eigenstates m1 m2 m3 Pontecorvo-Maki-Nakagawa-Sakata Matrix (CKM matrix in lepton sector) Atm/Acc Acc/Reactor Sol/Reactor 6 independent parameters govern oscillation q12, q23, q13, d Dm122, Dm232, Dm132 Dmij=mi2-mj2 2

  3. Present knowledge (before June, 2011) ne?? Sol/Reactor n3 Atm/Acc n2 OR n1 dunkown Which?? Big diff from KM matrix

  4. Indications of large q13 T2K 6event obs. 1.5 BG exp’ed 2.5s (June 13,2011) MINOS 62event obs. 49.5 BG exp’ed 1.7s (June 24,2011)

  5. New results on nm disappearance • T2K released the first disappearance result • Consistent with MINOS & SK results • MINOS data indicates slight tension between nm and anti-nm

  6. What’s next? • Immediate issues with on-going experiments • EXPERIMENTALLY establish non-zero q13 as soon as possible • Precise measurement of q23, Dm23 (both for nm and anti-nm), whether maximal mixing or not? • Next most important goal: CPV • CP is violated/conserved in neutrino? • What is the mechanism of violation? PMNS-type “standard” scenario or anything exotic origin?

  7. Toward one of big goals of particle physics: Origin of Matter-dominated UnvierseSakhalov’s 3 conditions • Baryon number violation • Proton decay • CP violation • Quark CPV seems not sufficient • Lepton CPV may contribute • Non-equilibulium

  8. nmne appearance and CPV ne appearance is golden mode for CPV IF ne appearance exist No CPV effect in disappearance Only nm beam is presently technically available Small leading CPC term  Large CPV effect (⇔nt app.) CPV Sol term CPV effect Unknown! (sinq12~0.5, sinq23~0.7, sinq13<0.2) The size of q13 decide future dir.! 8

  9. Expected CPV (&matter) effects (w/ “standard” PMNS framework) 1st peak @ 295km (0.6GeV) 1st peak @ 2300km (4.65GeV) 2nd peak @ 2300km (1.6GeV) T2K 90% region T2K 90% region • ~20% CPV effect at sin22q13=0.1 w/ sindCP=1 (max. vio.) at 1st peak • To detect CPV >3s for sind>0.2 (Asym=4%) O(10k) events necessary • Much higher statistics is necessary  >MW proton & huge detector mandatory • CPV asymmetry get smaller for larger q13 • Severer requirement on systematic error • Matter effect becomes comparable (@295km) or dominant (2300km) at 1st peak ( potential to determine mass hierarchy ) • CPV asymmetry get much larger for 2nd peak • Matter effect become small correction Pure matter effect Pure CPV effect T2K 90% region

  10. Essential requirements for CPV discovery • Order of magnitude higher statistics from present generation experiments •  • High intensity beam(Multi-MW) • Increase statistics • High sensitivity huge detector • Increase statistics • Increase signal efficiency • Reduce background • Reduce systematic errors • Should also capable for proton decay detection

  11. How to measure CPV & sign(Dm23) νe appearance energy spectrum shape Peak position and height for 1st, 2nd maximum and minimum Measure both sind & cosd terms  can discriminate 0deg vs 180deg Difference between νe and νe behavior Sensitive to any mechanism to make asymmetry (No assumption) Basically measure sindterm Distance: Larger L Matter effect large  Sensitive to sign(Dm23) too Smaller L (lower E): Purer CPV measurement 665km 2300km CPV Matter 11

  12. Future MW proton facilities in the world Staged approach

  13. “Available” technologies for huge detector Good at low E (<1GeV) narrow band beam LiqAr TPC • Aim O(100kton) • Electronic “bubble chamber” • Can track every charged particle • Down to very low energy • Neutrino energy reconstruction by eg. total energy • No need to assume process type • Capable upto high energy • Good PID w/ dE/dx, pi0 rejection • Realized O(1kton) Water Cherenkov • Aim O(1000kton) • Energy reconstruction assuming Ccqe • Effective < 1GeV • Good PID (m/e) at low energy • Cherenkov threshold • Realized 50kton Good at Wideband beam

  14. Possible experimental configuration • Multi-MW beam + Longer distance O(1000km)+ Wide band beam + LiqAr • Energy spectrum measurement • Cover both 1st and 2nd peaks • Possible to determine “everything” in 1 shot • CPV • Hierarchy • q23 octant • Multi-MW beam + Shorter distance (a few 100km) + Low energy narrow band beam + Water Cherenkov • Nue/nuebarasymtery of 1st peak • Possible to determine • CPV • Need external input to discriminate mass hierarchy (such as atm nu)

  15. Planned future CPV experiments

  16. Scenarios in Japan Kamioka L=295km OA=2.5deg Okinoshima L=658km OA=0.78deg Almost On-Axis J-PARC 1.7MW ??MW P32 proposal (Lar TPC R&D) Recommended by J-PARC PAC (Jan 2010), arXiv:0804.2111

  17. J-PARC-HyperK @ Kamioka leptonic CPV w/ JPARC n • Very good chance to detect CPV & have potential on sign(Dm23) with atmn sin2q23=0.6 sin2q23=0.5 sin2q23=0.4 mass hierarchy determination w/ atmospheric n 3s 10 yrs exposure of atm. n data. Super-K syst. errors are assumed. 5yrs of 1.66 MW JPARC n data. 5% syst. errors are assumed.

  18. Hyper-K Base-Design • 1Mton total volume, twin cavity • 0.54Mton fiducial volume • Inner (D43m x L250m) x 2 • Outer Detector >2m • Photo coverage 20% (1/2 x SK) 20” PMT w/ cover • Base-design to be optimized • Geological survey of the site is going on • Qualitative studies on physics potential FEM analysis (Factor of safety)

  19. J-PARC to Okinoshima Scenario 1 P32 proposal (Lar TPC R&D) Recommended by J-PARC PAC (Jan 2010), arXiv:0804.2111

  20. J-PARC to Okinoshima Scenario 1 P32 proposal (Lar TPC R&D) Recommended by J-PARC PAC (Jan 2010), arXiv:0804.2111

  21. Physics potential CPV Hierarchy Beam νe Background • Very good chance both to detect CPV & determine sign(Dm23)

  22. European Activities: LAGUNA-LBNO GLACIER ~500kt Water Cherenkov 100kt Liq Ar. TPC

  23. LAGUNA-Pyhasalmi sensitivity CPV Mass hierarchy unknown assumption A.Rubbia EPS-HEP 2011

  24. R&D toward realizing 100kt LArTPC J-PARC T32 exp (ETHZ/KEK/Iwate/Waseda) Double phase readout test @ ETHZ (CERN RE18) 250L LAr TPC 180k trig (80k Kaon) Site visit

  25. LBNE in US B.Svoboda, GLA2011

  26. US-LBNE sensitivities T2K region T2K region T2K region T2K region L.Whitehead, B.Rebel @ NNN2010

  27. Implication of large q13 on Future • If sin22q13> ~0.01 • Conventional Multi-MW super beam long baseline experiment will be really promising to explore CPV in lepton sector • We need to put even more effort to formulate the future project in this direction as soon as possible • IF not • Need “ideal” beam such as Neutrino Factory or beta beam to probe CPV T2K region

  28. Summary • Indication of large q13 makes conventional beam long baseline experiment be promising to probe CPV and sign(Dm232) • To realize the next generation experiment, Multi-MW beam power & High sensitivity huge detector MUST BE REALIZED • Two detector options are under consideration: • O(500kt) Water Cherenkov & 100kton LiqAr TPC • Two promising experimental configurations • WBB w/ LiqAr TPC  Spectrum measurement for 1st & 2nd peak • NBB w/ WC  n/anti-n asymmetry • Design study & R&D for future CPV search are intensively being done around the world • J-PARC  Kamioka (WC)/Okinoshima(LAr) • CERN Frejus(WC)/Pihasalmi(LAr) (LAGUNA-LBNO) • FNAL DUSEL (WC/LAr) (LBNE) • It is desirable to realize both configurations in the world, but it may not be so easy • Need to be very careful on physics potential • Personally, I am interested in how to know origin of CPV, whether PMNS or something exotic • International cooperation & coordination needed • EU/Russia/Japan(KEK) are working coherently under LAGUNA consortium • Need to be ready to “go” when finite q13 is concluded

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